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The present paper describes a new monoclonal antibody (K 1361) raised against hairy cell leukaemia cells. Antibody K861 recognizes a molecule of approximately 40,000 molecular weight on human B cells. It reacts with B lymphocytes in the peripheral blood, in primary lymphoid follicles, in the mantle zone of secondary follicles, in interfollicular areas and in splenic marginal zone areas. However, germinal centre lymphoid cells do not express the antigen recognized by antibody KB6I. The antibody shows limited reactivity outside the lymphoid system, i.e. polymorphs, tissue macrophages endothelial cells in the hepatic sinusoids. Antibody K861 discriminates between different types of B- cell malignancies, reacting with the neoplastic cells in hairy cell leukaemia, chronic lymphocytic leukaemia (of B-cell type), prolymphocytic leukaemia and centrocytic lymphoma, but not with acute lymphoblastic leukaemia, germinal centre-derived lymphomas (other than centrocytic), Burkitt's lymphoma and lymphoblastic lymphoma. Antibody KB61 may be of value in the study of B-cell subpopulations and in the differential diagnosis of B-cell neoplasms. [ABSTRACT FROM AUTHOR]

We demonstrated the efficacy of a long- term cultured cytotoxic T-lymphocyte line, CTLL-D4, on tumour growth inhibition using athymic nude mice as recipients. CTLL-D4, specific for a unique surface determinant on a radiation-induced leukaemia RL♂1 of BALB/c origin, was obtained from the limiting dilution culture of MLTC cells performed between spleen cells of a CS6F1-nu/ + mouse immunized in vivo and RL♂1 stimulator cells, and cultured for several months in the absence of added TCGF as described in our preceding paper (Kuribayashi, 1985). The specific inhibition of tumour growth by CTLL-D4 was demonstrated both in Winn-type neutralization assay and in systemic transfer experiments. A subcutaneous inoculation of the mixture of CTLL-D4 and RL♂1 cells resulted in the complete inhibition of tumour growth, even at the effector to tumour cell ratio of 1 : 1, whereas non-cytolytic D4f, which was self-Ia antigen(s)-reactive, composed entirely of Lyt-l + 23- T cells and derived originally from CTLL-D4 but completely lost its cytotoxic activity during culture with the irradiated syngeneic feeder cells alone, had no inhibitory effect at all. In the adoptive transfer studies, the subcutaneously established tumours were rejected by the single i.v. transfer of 2 × 107 CTLL-D4 cells into CB6F1-nu/nu mice. However, D4f was ineffective again in this systemic transfer system. When the effect of CTLL-D4 cells on tumour rejection in vivo was compared to that of non-cultured spleen cells hyperimmunized with RL♂1 cells, the former exhibited more rapid rejection in nude mice after i.v. transfer than the latter did, suggesting that CTLL-D4 cells also attack the tumour cells much more effectively as effectors in vivo. Thus, it is conceivable that CTLs are mainly involved in tumour rejection in this adoptive transfer system using RL♂ 1 tumour cells and athymic nude mice. [ABSTRACT FROM AUTHOR]

Pretreatment of mice by intravenous injection with killed Listeria provided neither delayed-type hypersensitivity to Listeria protoplasm nor protection against Listeria infection. Assuming that this suppression is due to suppressor cells, we attempted to clarify their induction and characterization. Pretreatment with killed BCG instead of killed Listeria suppressed the induction of DTH and protection in subsequent Listeria-immunized mice. Conversely, pretreatment with killed Listeria suppressed subsequent induction of DTH to PPD or protection from tuberculosis. Thus, these suppressions were. induced antigen non- specifically. Transfer of splenic non-adherent cells from killed Listeria-injected mice which had been treated with anti-BAθ serum plus complement, or had been passed through Sephadex G-10 columns, resulted in both afferent and efferent DTH suppression, suggesting that the DTH suppression is closely associated with suppressor T cells. Moreover, the splenic non-adherent cells from killed Listeria-injected mice showed suppression in vitro of listericidal activity of PEC from Listeria-immune mice in the presence of Listeria protoplasm. [ABSTRACT FROM AUTHOR]

In this paper, we describe the activity of conjugates constituted of monoclonal antibodies chemically coupled to ricin and the ricin A-chain-like toxin gelonin. Several antibody-toxin conjugates (immunotoxins) were assayed against a Thy 1.2+ and Lyt 2.2+ T-cell line. Anti-Thy 1.2-gelonin and anti-Lyt 2.2-ricin immunotoxins (IT) had a good cytotoxic activity against target cells, whereas anti-Lyt 2.2-gelonin showed weak or no cytotoxicity. An anti-Lyt 2.2-gelonin IT displayed detectable cytotoxicity only when cells were pretreated with ammonium chloride. IT binding activity was very similar for anti-Thy 1.2 and anti-Lyt 2.2 IT, and surface antigen density was of the same order of magnitude for Thy 1.2 and Lyt 2.2 antigens. Our results suggest that intrinsic properties of the surface target antigen are able to influence the IT cytotoxic efficacy. [ABSTRACT FROM AUTHOR]

It has been reported that, in early pregnancy in mice, there is an increase in the number of immunoglobulin-secreting cells in the lymph nodes which drain the uterus. This paper describes the results of further investigations provoked by interest in these early changes. Increases in the numbers of immunoglobulin-secreting cells were observed in syngeneically, but scarcely or not at all in allogeneically, mated mice. Increases were not observed in surgically sterilized female mice inseminated by normal males. However, subcutaneous injection of sperm provoked massive increases in the numbers of immunoglobulin-secreting cells in the lymph nodes draining the injection site. The changes were compared with those provoked by the injection of spleen cells and LPS. The results are discussed in relation to (i) the nature of the interactions provoking the increases in the number of immunoglobulin-secreting cells and their possible relationship to immunosuppression, and (ii) the relative immunological unresponsiveness which the female shows to the challenge of inseminated sperm. [ABSTRACT FROM AUTHOR]

Previous work from this laboratory has shown that preimmunization of syngeneic hosts with Rous sarcoma virus (RSV)-transformed cells elicits a strong immune response against the growth of transplantable RSV sarcomas, mediated by T lymphocytes expressing the surface phenotype of helper cell precursors (Prat, Di Renzo & Comoglio, 1983). This paper shows that anti-tumour immunity may be elicited in tumour-bearing animals by triggering an experimentally pre-amplified T-helper cell population at the site of tumour growth. Mice were treated with cyclophosphamide (which inactivates suppressor T cells) followed by skin sensitization to trinitrochlorobenzene (TNCB) according to a protocol that has been shown to induce an appreciably amplified generation of trinitrophenyl (TNP)-reactive helper T cells (Fujiwara et al., 1984). Five weeks after TNCB painting, mice were transplanted s.c. with a lethal dose of RSV-induced syngeneic sarcoma cells; the injection at the tumour site of TNCB induced the regression of the tumour in mice in which the TNP-helper cell population has been amplified, but not in controls, including those injected with a non-related hapten or sensitized to TNCB without inactivation of suppressors. [ABSTRACT FROM AUTHOR]

This paper describes some of the characteristics of a suppressor cell which is capable of regulating a rat RBC-induced autoantibody response against mouse RBCs. This cell, which appears to function as an inducer of suppression on transfer to naive recipients, is sensitive to Iow doses of cyclophosphamide, and its generation is affected by iow doses of irradiation. However, the recipients of these cells arc insensitive to cyclophosphamide treatment, suppression still being induced in such animals. [ABSTRACT FROM AUTHOR]

There is considerable confusion over whether the antigen-specific T suppressor factors (TsF) described by different authors are indeed equivalent. This paper investigates whether monoclonal TsF3, obtained from hybridomas derived from mice injected subcutaneously with NP derived spleen cells. is functionally equivalent to the conventional T suppresser factor, produced by mice injected intravenously with chemically reactive, water soluble haptene (picrylsulphonic acid and oxazolone thioglycolic acid). Comparison of monoclonal anti-NP TsF3 with conventional anti-picryl and anti-oxazolone T suppressor factor showed that both armed the non-specific T accepter cell (Tacc) which was sensitive to cyclophosphamide and adult thymectomy. Moreover, non-specific inhibitor (nsINH) of the transfer of contact sensitivity was released when antigen, together with major histocompatibility complex products (MHC). reacted with conventional or monoclonal TsF on the surface of the non-specific T accepter cell. The interaction of monoclonal TsF3 with antigen, which led to the release of nsINH, required the presence of MHC and was I-J restricted. However, there was no Igh-1 restriction. The equivalence of conventional anti-picryl and anti-oxazolone TsF has been demonstrated by arming the Tacc with a mixture of these two suppressor factors, and then triggering the release of nsINH with the mixed haptene ‘picryl-oxazolone-lysine’ which crosslinks separate molecules of TsF. A similar equivalence of conventional anti-oxazolone TsF and monoclonal anti-NP TsF3 was demonstrated using the mixed hapten ‘NP-oxazolone-lysine’ to trigger the release of nsINH. It was concluded that monoclonal TsF3 and conventional TsF were equivalent, and that both had an indirect mode of action through the non-specific T acceptor cell which led to the production of non-specific inhibitor. [ABSTRACT FROM AUTHOR]

CBA/N mice harbour an X-linked B cell defect which is transmitted by CBA/N female mice to their hybrid male progeny. These mice mount normal responses to thymus-dependent (TD) and some thymus-independent (TI-1) antigens, while the response to TI-2 antigens is absent. Hapten-specific plaque-forming cell (PFC) responses to TD antigens can be blockaded by concomitant exposure of these mice to TI-2 antigens bearing the same hapten. This paper investigates in defective mice the blockade of their response to TNP3-LPS (trinitrophenylated lipopolysaccharide, a TI-1 antigen), imposed by DNP59-Ficoll (dinitrophenylated Ficoll, a TI-2 antigen). The effectiveness of the blocking agent, DNP59-Ficoll, differed in various inbred mouse strains: CBA/N × C3H/HeN F1 male > CBA/N female > CBA/N · C3H/HeN F1 female. The role of T cells in the observed hapten-specific blockade phenomenon was investigated using athymic CBA/N nude mice and a B cell tolerogen. Our findings indicate that T cell participation is not essential for the blockade of CBA/N PFC responses and they suggest that direct blockade of TI- and TD-responsive B cell populations is likely to occur. [ABSTRACT FROM AUTHOR]

This paper described the influence of factor H on the haemolytic activity of the classical C5 convertase. Factor H showed little effect on the interaction of C5 with EACI,4b,2a,3b cells bearing low numbers of C3b sites, but displayed the inhibitory effect on the interaction of C5 with the intermediate cells bearing high numbers of C3b sites. The higher the number of C3b sites on the cells, the greater the degree of the inhibition by factor H. The inhibition by factor H was accompanied by the inhibition of consumption of CS from the fluid phase, indicating that factor H inhibits the activity of CS convertase, not the binding of activated CS to the cells. [ABSTRACT FROM AUTHOR]

In this paper we present experiments that indicate that, in man, most T-celI subpopulations produce interleukin-2 (IL-2), but that the main cell subpopulation which produces it, both upon activation with phytohaemagglutinin or in autologous mixed lymphocyte cultures, is that of autologous rosette-forming (Tar) T4+ T cells. Conversely, the main IL-2-responding T-cell subpopulation is that composed of T cells depleted of Tar (T-Tar) that are T8+ IL-2 was also found to be more effectively produced by Tar cells that do not bind peanut agglutinin (PNA) than by those that do. The PNA T4+ Tar cells were also found to respond best to interleukin- I (IL-I). [ABSTRACT FROM AUTHOR]

The results presented in this paper demonstrate that a mouse IgM monoclonal antibody (T-80) recognizes an antigen on cells of the T-lymphocyte lineage of sheep. However, this antibody does not identify all T cells, as 10-20% of thymocytes and some peripheral-blood T cells are negative. T-80- thymocytes reside in the medulla. The majority of cortical thymocytes are T-80+ and classified as dull cells on the basis of antigen density per cell as measured by flow microfluorometry. In contrast, T-80+ cells in the periphery can be categorized into two populations, i.e., dull cells and bright cells. Suggestive evidence was obtained that bright T-80+ cells are fast recirculating T cells, whereas dull ceils are sessile or less easily mobilizable T cells in the periphery. In foetal environment, over 90% of thymocytes and approximately 5% of spleen cells are T-80+ at 54 days of gestation (gestation period = 150 days), which may indicate that T-cell emigration from the thymus commences well before mid-gestation in sheep. [ABSTRACT FROM AUTHOR]

One of the T suppressor circuits induced by picrylsulphonic acid includes the T suppressor cell (Ts-eff) which acts at the efferent stage of the contact sensitivity reaction and produces antigen-specific T suppressor factor (TsF). This factor does not act directly but arms a T acceptor cell (Tacc). This Tacc liberates a non-specific inhibitor when it is armed with TsF and then exposed to picrylated cells sharing the I-J genotype of the source of the TsF. This paper investigates the role of I-J region gene products in this T suppressor circuit. Two approaches were used. Syngeneic CBA (H-2k) lymphocytes were separated into I-J+ and I-J- cells by treatment with anti-I-Jk serum followed by panning on anti-immunoglobulin plates. The cells were then picrylated and used as a source of antigen. Alternatively, B10.A congeneic mice syngeneic (SR) or allogeneic (3R) with CBA at the I-J locus were picrylated and used similarly. The main findings were as follows. (i) The intravenous injection of picrylated I-J+ spleen cells but not a similar number of I-J- cells induced Ts-eff which blocked the transfer of contact sensitivity. Picrylated unseparated cells syngeneic, but not allogeneic, at the I-J locus were also effective. (ii) It is known that the lymphocytes of mice injected with picrylsulphonic acid and then re-exposed to antigen by painting with picryl chloride liberate TsF in vitro. The re-exposure to antigen can be replaced by the intravenous injection of picrylated I-J+ cells or by cells syngeneic at the I-J locus the day before harvesting the spleen cells. (iii) The release of non-specific inhibitor by Tacc armed with TsF requires exposure to picrylated I-J+ cells or cells syngeneic at the I-J locus. The requirement for antigen on a cell bearing syngeneic I-J suggests that antigen together with I-J is an activation signal in this T-cell circuit. The simplest explanation is that the receptor of the pristine Ts and of the mature Ts-eff is similar to T suppressor factor. [ABSTRACT FROM AUTHOR]

A series of immunoassays have recently been elaborated in which the red cell is used as a label or marker of interacting antibody, often antiimmunoglobulin (anti-Ig). This paper considers and investigates quantifiably, the different variables which affect the sensitivity of direct and indirect antiglobulin rosetting reactions (DARR and IARR) and of reverse passive haemagglutination (RPH). Sensitivity is governed by the surface properties and amount of antibody on the indicator red cell and, in detection of cell-bound antigen, by the antigen density. By varying the antibody:Ig ratio on the red cell using affinity purified anti-Ig, cells with more than 1:32-64 antibody: Ig showed similar sensitivity in detection of lymphocyte sIg in DARR and IARR tests and of serum Ig by RPH. Using these indicator cells coupled with different Ab: Ig ratios to detect lymphocytes sensitized with different levels of anti-Ig in a model IARR test, it was clear that studying cells with a high density of determinants on the lymphocyte surface it is not necessary to have 'strong' antiimmunoglobulin on the indicator cell, but increasingly sparse determinants require increasingly strong anti-Ig on the red cell to detect all positively reacting cells. Red cells of different species afford carriers of varying sensitivity in all three reactions—DARR, IARR and RPH. Preliminary trypsin treatment may greatly further enhance the sensitivity of some species red blood cells (e.g. bovine and sheep), but leaves others (e.g. pig and donkey) unchanged. Use of 125I-labelled Ig and anti-Ig showed that the increased sensitivity of trypsinized bovine and sheep RBC is not due to increased uptake of Ig during chromic chloride linkage or of antibody in agglutinations. [ABSTRACT FROM AUTHOR]

This paper investigates desensitization in vitro, e.g. the inhibition of the transfer of contact sensitivity to picryl chloride by incubation of the passive transfer population with picrylated spleen cells. It asks whether desensitization is based on the same T-suppressor circuit which is responsible for the inhibition of passive transfer by antigen-specific T-suppressor factor (TsF). In this circuit, the T-suppressor cell which acts at the efferent stage (Ts-eff) makes TsF. This TsF depresses contact sensitivity indirectly by arming a T-acceptor cell (Tacc). The armed Tacc, when exposed to antigen (picrylated spleen cells), liberates a non-specific inhibitor which blocks the transfer of contact sensitivity. The three elements of this T-suppressor circuit occur in nylon wool-purified T cells prepared from the lymph nodes and spleens of mice four days after immunization with picryl chloride. This population transfers contact sensitivity and can be desensitized in vitro. It contains Ts-eff which can be isolated by panning (adherence) on picrylated albumin and detected by their ability to inhibit passive transfer. The 24 hr supernatant of cultures of these cells contains TsF. Finally the population contains Tacc which appear in the spleen 2 days after immunization and virtually disappear by 10 days. Further experiments demonstrated that the Ts-eff and the Tacc were not merely present but actually required for desensitization in vitro. Immune cells depleted of both Ts-eff (by panning on picrylated albumin) and Tacc (by arming with anti-oxazolone TsF and panning on oxazolonated albumin) cannot be desensitized. To restore desensitization both Ts-eff and Tacc must be added back. The Ts-eff were characterized as cyclophosphamide resistant, adult thymectomy sensitive cells (Cyr, ATx5), which adhered to antigen and were produced only by specific immunization. The Tacc were characterized as CF5, ATx5 cells which adhered to antigen only after arming with antigen-specific T-suppressor factor and were produced after immunization with an unrelated contact sensitizer, 'oxazolone'. It was concluded that desensitization in vitro was due to the interaction of two distinct T cells: the T-suppressor cell which acts at the efferent stage of the contact sensitivity reaction and the T-acceptor cell which becomes armed with the specific T-suppressor factor produced by the Ts-eff. [ABSTRACT FROM AUTHOR]

This paper describes a method for in vitro measurement of specific cell-mediated immunity in the mouse. Animals were immunized parenterally with ovalbumin in Freund's incomplete or complete adjuvant, and a direct migration inhibition assay was performed, using lymphoid cells from the draining lymph nodes. Migration inhibition was found to be antigen specific, correlated with systemic delayed-type hypersensitivity measured in vivo by skin testing, and had a high degree of sensitivity for ovalbumin. The migrating cells were identified as lymphocytes. Lymph node lymphocyte migration inhibition provides a reliable in vitro assay for regional CMl in the mouse. [ABSTRACT FROM AUTHOR]

The experiments described in this paper were designed to determine the degradation of soluble IgG aggregates (AIgG) bearing C3b by guinea-pig peritoneal macrophages with different numbers of functional C3b receptors. The number of functional Fc receptors for AIgG containing 40 molecules of IgG per aggregate (AIgG40) were kept constant during these experiments. By increasing the concentration of trypsin for the treatment of normal peritoneal macrophages a dose-dependent inactivation of C3b receptors was achieved as determined by the binding of tetrameric [125I]-C3b([125I]-AC3b). Normal peritoneal macrophages bound 148,500 AIgG40 and 60,300 AC3b per cell. Treatment of the macrophages for 15 rain at 37° with incremental amounts of trypsin from 60 to 1000 µg/ml did not affect the binding of AIgG40 to macrophages but caused a dose-related loss of up to 95% of AC3b binding, indicating functional inactivation of C3b receptors. Degradation of trichloroacetic acid non-precipitable protein of [125I]-AIgG40 by 106 macrophages was 38±6% in medium alone and 60 ±8% in the presence of 10% fresh guinea-pig serum (NGPS) after 60 rain at 37°. The inactivation of 25%, 50%, 72% and 94% of C3b receptors by trypsin did not affect the degradation of AIgG40 in medium alone, but decreased degradation from 69% to 58%, 47%, 32% and 13% of AIgG40 respectively, in the presence of 10% GPS. Macrophages (106) in medium alone degraded 40%, 47%, 65% and 68% of AIgG40 beating 0, 5, 10, 16 and 20 C3b molecules per aggregate, indicating a dose-dependent enhancement of degradation by bound C3b; conversely, inactivation of 95% of C3 receptor on the macrophages resulted in 39%, 30%, 12%, 5% and 6% degradation of these AIgG40-C3b, indicating a dose-related inhibition by aggregate-bound C3b in the absence of cellular C3 receptor. These experiments stress the importance of Fc and C3b receptor co-operation and immune complex bound C3b. [ABSTRACT FROM AUTHOR]

The results of experiments reported in this paper show that intravenously injected human IgM rheumatoid factor binds in vivo to immune complexes previously deposited in mouse glomerulus. Prior injection of human IgM rheumatoid factor does not interfere with glomerular deposition of passively administered immune complexes. Evidence is presented to show that rheumatoid factor once attached to glomerular bound immune complexes is able to act as an immunoabsorbent and to bind further circulating complexes. [ABSTRACT FROM AUTHOR]

Macrophage agglutination factor (MAggF) is a T-cell-dependent guinea-pig lymphokine with pH stability, heat stability and isoelectric point similar to fibronectin (see preceeding paper for details). Further observations confirm the similarity between MAggF and fibronectin. MAggF in unconcentrated lymph node cell culture supernatants bound reversibly to gelatin and fibrinogen. On gel filtration chromatography, most MAggF activity in a pooled concentrated lymphokine preparation was associated with molecules of 370,000 Daltons; lesser amounts of activity were found at 240,000 and 50,000 Daltons. All molecular weight forms of MAggF bound reversibly to gelatin. Guinea-pig plasma fibronectin prepared by affinity chromatography over gelatin had a molecular weight of about 450,000, a sub-unit on reduction of about 240,000 Daltons, and showed partial antigenic identity with human plasma fibronectin. Human and guinea-pig plasma fibronectin preparations showed MAggF activity when tested using guinea-pig peritoneal macrophages, but their potencies relative to a culture supernatant standard did not correlate with the content of immunoprecipitable fibronectin measured by anti-human fibronectin antiserum. However, anti-human fibronectin immunoadsorbents specifically and reversibly bound MAggF activity in culture supernatants. On the basis of our observations, we suggest MAggF is a guinea-pig tissue fibronectin. [ABSTRACT FROM AUTHOR]

In the previous paper we reported that human natural killer (NK) cell activity was augmented greatly by preincubation with Staphylococcus aureus Cowan I bacteria (SpA CoI) or its Protein A. We examined here whether the augmentation with these stimulants is ascribable to the direct activation of NK cells or mediated by some soluble factors produced by the stimulants. It was found that a significant amount of interferon (IFN) was produced by the SpA CoI-stimulation but not by the Protein A-stimulation, although the latter usually induced augmentation of NK-cell activity not less than SpA CoI-stimulation. IFN produced by SpA CoI was considered to belong to α-type IFN, because it was stable at pH 2.0 and could be neutralized effectively by anti-IFNα antibody. Kinetics of NK-cell activation by SpA CoI (but not by Protein A) were very similar to those by IFNα. Furthermore, augmentation of NK-cell activity with SpA CoI-stimulated supernatant was inhibited almost completely by diluted anti-IFNα antibody, whereas augmentation with Protein A-stimulated supernatant could not be abolished by the same treatment. It was, therefore, suggested that augmentation of NK-cell activity with SpA CoI might be ascribable in most part to the IFN induced, whereas Protein A can stimulate NK or T cells directly or soluble factors other than IFN might work as well. [ABSTRACT FROM AUTHOR]

In this paper we describe the first in vitro response to the liver alloantigen F. The anti-F response serves as a valuable model for autoimmune phenomena since priming appropriate strains of mice (responders) with allogeneic but not syngeneic type F leads to autoantibody production. The in vitro system is based on the proliferation of T cells, from mice primed in vivo with F, when coincubated with splenic adherent cells (SAC) prepulsed with F in vivo. The system displays two important correlates of the in vivo antibody response to F:1.T cells from mice primed with syngeneic F do not proliferate when incubated with SAC prepulsed with syngeneic F and 2. Mice that do not make antibody responses to allo F in vivo (DBA/2) do not show in vitro proliferative responses. These findings indicate that the proliferative assay is a good in vitro model for the F response. [ABSTRACT FROM AUTHOR]

The interaction of L5178Y thymic lymphoma cells syngencic to DBA/2 mice and of normal thymocytes with goat IgG antibodies was studied in vitro. Viable turnout and normal cells exerted a rapid, continuous and temperature-dependent destruction of antibody activity. Fractionation studies of culture supernatants from antibody-coated cells revealed that a significant portion of the antibody was completely degraded to amino acids. Tumour cells digested antibody more effectively than did normal lymphocytes. This observed degradation of antibody was most extensive at 37°, significantly less at room temperature (23°) and not detectable at 0°. Undegraded antibody released from antibody-coated cells had also lost its antibody activity to a considerable extent. This was due to the formation of soluble antigen-antibody complexes, which was observed even at 0°. Cells fixed with 10% formalin bound maximum amounts of antibody were incapable of digesting antibody even at 37° and did not release immune complexes. These findings are of relevance to cancer immunodiagnosis and immunotherapy. [ABSTRACT FROM AUTHOR]

Murine lymphocytes spontaneously bind autologous and allogeneic erythrocytes via receptors that primarily recognize self H-2L molecules on the erythrocyte surface. Normal mouse serum contains a factor, termed autorosette inhibition factor (AIF), that very effectively blocks autorosette formation. This paper describes experiments that determine the origin and nature of serum AIF. It was found that AIF lacks strain and species , serum from several mammalian and nonmammalian species inhibiting the autorosetting of BALB/c thymocytes. However, mouse strains differed in the levels of AIF in their serum. Furthermore, AIF appears to directly interact with autorosetting roceptors on lymphocytes as thymocytes from the BALB/c-H-2dm2 mutant strain, which lack autorosetting receptors, were unable to absorb the factor. Several lines of experimental evidence indicated that AIF is secreted by a population of short-lived, radiosensitive macrophages (or monocytes). Firstly, in vivo administration of the anti-macrophage agents carrageenan and silica profoundly depressed AIF levels in serum. Secondly, in vitro culturing of different lymphoid cells revealed that AIF is secreted by an adherent population of peritoneal cells. Thirdly, total body irradiation experiments demonstrated that AIF production is dependent upon a radiosensitive cell that is bone marrow derived. Finally, AIF was purified to homogeneity from mouse plasma and shown to be a single polypeptide chain with a molecular weight of 84,000. [ABSTRACT FROM AUTHOR]

A comparative study has been made of human precipitating and co-precipitating anti-tetanus toxin antibodies. IgO co-precipitating antibody represented 10% of the total antibodies in the serum and had immunological and biological properties similar to those described for co-precipitating antibodies of other animal species. Human precipitating and co-precipitating anti- bodies had the same electrophoretic mobility and were localized in the same immunoglobulin fraction. By immunoprecipitation it was not possible to find antigenic differences between precipitating and co-precipitating antibodies. Both antibodies were localized in the IgG1 and IgG3 subclasses and neither were in the IgG4 subclass. Only the precipitating antibody can form insoluble complexes with antigen. Precipitating and co-precipitating antibodies agglutinated sensitized sheep red cells, however, only the precipitating antibody agglutinated human red cells. Eight to ten times more co-precipitating antibody was required to obtain a positive reaction in PCA. Precipitating antibody activated the complement system while co-precipitating antibody lacked this capacity. This difference in behaviour could not be attributed to localization of both antibodies in different IgO subclasses. Precipitating and co-precipitating antibodies were cytophilic. Only the former activated phagocytosis and increased clearance of antigen from the blood. These results are not surprising since co-precipitating antibody does not fix complement. Competition between human precipitating and co-precipitating antibodies in opsonization was analysed. In this test competition of both antibodies for the antigen depends on their respective amounts The K= 0.18 diminished to 005 when the ratio of pp:cop. antibody changed from 10:30 to 30:70. The fact that co-precipitating antibody was isolated from the sera of vertebrates other than man indicate that this antibody could possibly play a role in some immune mechanisms. Taking into account that in previous papers we have demonstrated that co-precipitating antibody functions as a molecule with one combining site of high affinity and one of low affinity, we have proposed that this antibody could function univalently and blocks the antigen. This could facilitate chronic parasitic, bacterial and viral infections, tumour growth and other chronic infections. [ABSTRACT FROM AUTHOR]

This paper describes the effect of altering liposomal membrane composition on humoral and cellular immunogenicity of haptenated liposomes in mice. Antibody formation was determined by enumeration of direct, plaque-forming cells in the spleen and delayed-type hypersensitivity (DH) was measured with a footpad swelling test. Humoral immunogenicity of haptenated liposomes was strongly influenced by membrane phospholipid, cholesterol and charged amphiphile composition. Haptenated liposomes prepared from phospholipids with a low (diolcoyl- and dilauroyl-phosphatidylcho- line) or high (distearoyl phosphatidylcholine) phase- transition temperature were less immunogenic than those prepared from phospholipids with an intermediate phase-transition temperature (dipalmitoyl phosphatidylcholine and sphingomyelin). In general, increasing the amount of liposomal membrane cholesterol induced a higher humoral response. These results are discussed in relation to liposomal membrane fluidity. Induction of an optimal DH with haptenated liposomes did not occur in the absence of the adjuvant dimethyl dioctadecyl ammonium bromide (DDA). When DDA was used, alterations in membrane composition did not influence cellular immunogenicity. From these results it was concluded that ‘intermediate’ liposomal membrane fluidity is the most important requirement for induction of optimal antibody formation with haptenated liposomes and that a certain physicochemical configuration of the antigen, provided by the adjuvant DDA, is a prerequisite for induction of DH. [ABSTRACT FROM AUTHOR]

This paper describes the induction of IgM immune memory to haptenated liposomes in mice. The tripeptide-enlarged haptens 3-(p-azo-benzene-arsonate)-N-acetyi-L-tyrosylglycyiglycine (A) and N-(2,4-dinitrophenyl)-β-alanylglycylglycine (J) were coupled to phosphatidylethanola mine (PE) and the conjugates A-PE and J-PE were incorporated into separate liposomal membranes (monofunctional A-PE-liposomes or J-PE-Liposomes) or into the same liposomal membranes [bifunctional (A,J)PE-liposomes]. The magnitude of the humoral response was measured by the appearance of direct and indirect plaque-forming cells in the spleens of immunized mice. Intracutaneous priming of mice with A-PE-liposomes mixed with the adjuvant dimethyl dioctadecyl ammonium bromide (DDA) and secondary immunization with bifunctional (A.J)-PE-liposomes resulted in enhanced hapten A- and J-specific IgM responses. However, no switch from IgM to IgG antibodies was observed in these mice. The J-specific IgM response was enhanced only when hapten I was incorporated into a bifunctional liposome which also contained A-epitopes. in mice primed with A-PE-liposomes in the absence of DDA, a greatly diminished memory to both hapten A and J was observed. This finding indicates a crucial role for the adjuvant in the induction of memory. J-PE-liposomes and DDA were not able to induce memory to monofunctional J-PE-liposomes or bifunctional (A,J)-PE-liposomes. The possibility that hapten A-specific B lymphocytes were responsible for the induction of memory was excluded by hapten-specific blockade of these cells with a B-cell tolerogen. These data, in addition to the observation that no IgM memory could be induced in congenitally athymic nude mice, suggest that the observed memory can be ascribed to priming of hapten A-specific T lymphocytes. [ABSTRACT FROM AUTHOR]

The intravenous injection into mice of small amounts of heat-aggregated bovine serum albumin (BSA) results in deposition of BSA within the glomerulus. Injection of rabbit anti-BSA antibody at a time when all circulating BSA has been cleared results in in situ formation of BSA anti-BSA immune complexes with fixation of mouse C3. Subsequent injection of passively-prepared immune complexes gives much enhanced deposition of immune material when com- pared with mice given immune complexes alone. This paper shows that this is an antigen-specific phenomenon and not a result of non-specific trapping by damaged glomeruli. The implications of these observations on the pathogenesis of immune complex glomerulonephritis are discussed. [ABSTRACT FROM AUTHOR]

This paper describes the induction of delayed-type hypersensitivity (DH) in the mouse and guinea-pig to haptenated liposomes. The tripeptide- enlarged hapten 3-(p-azobenzenearsonate)-N-acetyl- L-tyrosylglycylglycine (A) was coupled to phosphatidylethanolamine (PE) and incorporated into liposomal membranes (A PE-liposomes). In mice DH was measured as footpad swelling and in guinea pigs by skin testing. To induce hapten A-specific DH in mice with A-PE- liposomes the application of the cationic, surface- active lipid, dimethyl dioctadecyl ammonium bromide (DDA) was necessary. The use of Freund's complete adjuvant (FCA) did not result in the induction of DH to hapten A. In guinea-pigs, however, FCA and DDA had equally good adjuvant properties in the induction of DH. The time course of the DH and the optimal time interval between immunization and elicitation were determined for the mouse system. Also, the effect of dose and epitope density was studied in that system. Cyclophosphamide treatment, before immunizing mice with A-PE-liposomes and DDA, resulted in greatly impaired DH, probably caused by the short lifetime of the integrity of liposomes after intracutaneous administration to mice. The results make it very likely that presentation of hapten A in a liposomal or micellar structure is required to induce a cellular immune response to this hapten in mice. [ABSTRACT FROM AUTHOR]

Bovine peripheral blood monocytes were isolated from bully coats of ACD-anticoagulated whole blood. Cells cultivated on plastic surfaces for 20 h were judged to be 95% thonocytes based on non- specificesterase-l staining, uptakeoflatexparticlesand surface receptor characteristics. Bovine monocytes were maintained up to 80 days in vitro in Dulbecco's modified Eagle medium with 15% horse serum and 15% foetal bovine serum. Several morphological and physiological features of bovine monocytes were examined during the course of culture. Cell size and cytoplasmic spreading, granulation and vacuolization increased progressively. Multinucleated giant cells pre- dominated during the latter stages of in vitro culture A high percentage of bovine monocytes possessed C3 and IgU Fc receptors, whereas 1gM Fc and sheep erythrocyte receptors were not detected. Phagocytosis was mediated by the IgG receptor, but not by the C3 receptor. Peroxidase activity declined in a linear fashion, with cells essentially negative after 8 days of culture. Total cell protein and acid phosphatase increased during cultivation. Lysozyme activity was undetectable in both lysates and supernatants of bovine monocyte. These findings are consistent with the concept of maturation of mononuclear phagocytes. The procedures for isolation and cultivation described in this paper will provide methodology for detailed study of bovine mononuclear phagocytes. [ABSTRACT FROM AUTHOR]

We report the complete sequence of a cyanogen bromide fragment of a human δ chain (En). Its interest lies in the fact that it contains the peptide joining the Vδ to the Cδ1 region. The presented sequence is compared with the homologous region of other human heavy chain classes and subclasses. The possibility that human 6 chains and other human heavy chains have in their chromosornal DNA a short J sequence, is discussed. [ABSTRACT FROM AUTHOR]

This paper describes a rather simple coupling method for tripeptide enlarged haptens to phosphatidylethanolamine (PE) and the incorporation of these conjugates into liposomal model membranes (haptenated liposomes). These haptenated liposomes evoke a hapten-specific humoral immune response in mice. The magnitude of the response as measured by the appearance of direct plaque forming cells in the spleen is dependent on the route of immunization and the dose and epitope density of the hapten-PE derivatives. It was not possible to evoke an IgG response after either primary or secondary immunization with haptenated liposomes (as measured by the production of indirect plaques or mercaptoethanol-resistant antibody). These data, in addition to the observations that mice depleted of, or deficient in thymus-derived (T) lymphocytes respond to haptenated liposomes, indicate that these haptenated liposomes are T-cell independent antigens. [ABSTRACT FROM AUTHOR]

This paper uses B-lymphocyte cloning methods to quantify the effects of anti-μ chain antibody on immature and mature B cells. Nude mouse spleen lymphocytes were incubated with various concentrations of sheep anti-mouse μ chain antibody for times varying from 10 min to 24 h. They were then washed and plated in the agar B-cell colony formation assay. Five to six days later, control B cells had developed into colonies with a plating efficiency of about 5%. B cells from newborn mice pretreated with anti-μ yielded fewer colonies. Remarkably low concentrations sufficed to inhibit subsequent mitogenesis. For example, 3 μg/ml acting for 1 h or 0.1 μg/ml acting for 24 h gave > 50% inhibition. Adult B cells were about thirty-fold more resistant to negative signalling. Immature cells became more profoundly inhibited as anti-μ treatment was prolonged. Anti-Ia or anti-H2 antibodies, in the absence of complement, did not deliver a negative signal. Anti-μ pretreatment also reduced the capacity of immature B cells to form clones of anti-hapten antibody-forming cells in a liquid microculture system where the triggering stimulus was a T-cell independent antigen. Mature 'T-independent' B cells were not inhibited. Populations of hapten-specific B cells prepared by the hapten-gelatin method were investigated in the agar cloning system. Pretreatment of immature cells with anti-μ reduced their capacity to form colonies, this subpopulation of cells behaving like unfractionated B cells. Furthermore, hapten--HGG delivered a negative signal also. Mature hapten-specific cells or unfractionated immature spleen cells formed normal numbers of colonies following hapten HGG treatment. Overall, the studies support the view that anti-μ antibody and hapten--HGG deliver strong negative signals to immature but not mature cells with appropriate receptors. The value of anti-μ as a model, universal tolerogen was supported. Fluorescence-activated cell sorter (FACS) analysis was performed to study the relationships between functional inhibition and Ig receptor modulation. We confirmed that the IgM receptors of immature B cells are more readily modulated by anti-μ antibody than those of mature cells. Furthermore, the receptor regeneration could be partially inhibited amongst immature but not mature B cells. There was not a close quantitative relationship between the degree of modulation and the degree of functional inhibition. The results did not support the view that irreversible receptor modulation as such was the cause of functional inhibition. [ABSTRACT FROM AUTHOR]

Plaque-forming cell responses and antibody titres to sheep red cells (SRC) were elevated in normally-fed irradiated adult mice reconstituted with spleen cells from young mice which had received a 4% albumin diet, compared with those given cells from normally-fed littermates. This was independent of the dose of cells transferred (5 × 106-4 × 107), the day of assay (3–10) and the duration of protein-deficiency (1 or 3 weeks). It suggests that the depressed responses produced by protein-deficient (donor) mice reported in earlier papers resulted from an impairment of reticuloendothelial function or a shortage of protein reserves, not directly associated with the spleen. As protein-deficiency (of the donor) accelerated the initiation of the adoptive response and increased the cell yields of the recipients it is considered likely that an enhancement of cell proliferation during the first 3-5 days after transfer was responsible for the elevated responses. [ABSTRACT FROM AUTHOR]

Results of in vivo and in vitro experiments suggest that the early suppression of brucella growth in double stranded polyadenylic-polyuridylic acid(poly A: U-) treated mice was due to a non-specific activation of macrophages by poly A: U. Poly A: U administered intraperitoneally at the time of brucella infection failed to enhance T-cell mediated responses to the organism, namely delayed-type hypersensitivity to brucellin and adoptive transfer of immunity to the infection. Poly A: U did not augment the protective antibodies formed in response to infection. Although poly A:U has been previously found to suppress brucellosis in athymic (nude) mice, it did not enhance the thymus-dependent antibody response to sheep erythrocytes in brucella-infected nudes, suggesting that it did not significantly enhance maturation of their helper T-cell percursors. Increased macrophage spreading, an indication of activation, was seen immediately after administration of poly A: U and Brucella abortus. Later on the infection spreading was suppressed, a phenomenon which appears to relate to the biphasic effect of poly A: U in vivo described in the accompanying paper. Peritoneal macrophages treated in vitro with poly A: U were stimulated to spread on plastic surfaces, even when T lymphocytes were removed with anti-Thy-1 serum and complement. [ABSTRACT FROM AUTHOR]

In the present paper it is shown that the non-species specific determinant of the antigenic thymus-brain system previously detected in murine and human brain also exists in human thymus. However, in contrast to the situation in mice and rats this antigenic structure is not expressed on suspended thymic lymphocytes, but is associated with thymic tissue largely depleted of thymic lymphocytes. Moreover, this determinant is also detectable in human lymph nodes. Besides the non-species-specific antigenic determinant human thymus and brain also share a species-specific determinant. In contrast to the non species specific determinant this structure is also displayed by suspended thymic lymphocytes, certain peripheral blood lymphocytes and bone marrow cells. The non-species-specific determinant detected in human thymus is borne by a structure, which physico-chemically resembles the thymus-brain antigen isolated from murine brain and thymus as well as from human brain. Although the structure bearing the species specific antigenic determinant has a similar apparent molecular weight both antigens could be separated by ion exchange chromatography indicating their molecular diversity. [ABSTRACT FROM AUTHOR]

Examines various types of T lymphocyte functions in the spleens of mice infected four days previously with Friend virus (FV) in order to analyze its effect on the antibody response. Finding that infection does not reduce the percentage of T lymphocytes in the spleen, nor the ability to respond to phytohemagglutinin (PHA); Results suggesting that FV does not affect spleen T lymphocyte proliferation or helper function; Conclusion that the immune defect resides in the B lymphocytes.

Mouse bone marrow is capable of a distinct plaque-forming cell (PFC) response after i.v. immunization with the thymus-independent antigen E. coli lipopolysaccharide (LPS). Both during the primary and secondary response to i.v. administered LPS the spleen contained the majority of PFC until about 5 days after immunization. In the course of the reaction the number of PFC in the bone marrow rose to a level which surpassed the level in the spleen. This paper deals with the regulating influence of the spleen on the primary and secondary anti-LPS PFC response in the bone marrow. Splenectomy prior to the first injection of 5 μg LPS i.v. initially did not affect the bone marrow PFC response. However, at the 7th day after immunization the PFC response in the bone marrow fell to only 10 per cent of the bone marrow PFC activity in sham-splenectomized mice. In contrast to the primary response no regulating influence of the spleen on the bone marrow PFC activity could be demonstrated during the secondary response. The influence of splenectomy on the appearance of B-memory cells in the bone marrow depended on the priming dose. The appearance of LPS-specific B-memory cells in the bone marrow was not affected by splenectomy at priming doses of LPS as high as 1 and 0.1 μg. On the other hand splenectomy before 0.01 μg LPS i.v. reduced, and splenectomy prior to 0.001 μg LPS i.v. completely prevented the appearance of B-memory cells in the bone marrow. [ABSTRACT FROM AUTHOR]

This paper describes experiments under-taken to determine more uniform conditions for the generation of cytotoxic lymphokine -- 'lymphotoxin' (LT) in differently stimulated rat lymphocyte cultures, and to compare the sensitivity of different test systems for detecting rat LT activity in vitro. Wistar rat lymphoid cells were activated by culture with phytohaemagglutinin (PHA) and mixed lymphocyte cultures (MLC) with semi-allogeneic (Wistar × August) F1 lymphoid cells. Lymphocyte supernatants harvested between 1 and 8 days were tested for theft effect on the metabolism and viability of cultured mouse fibroblasts (L-929 cells) by four methods: (i) inhibition of [14C]leucine incorporation; (ii) total and viable cell counts in test tube cultures ('macro test'); (iii) viable cell counts in microtitre plates ('micro test'); and (iv) chromium (51Cr) release from chromated L-cell monolayers. Cytotoxic effects on target cells of lymphocyte supernatants were evident after 3 days of PHA stimulation and 6 days of mixed lymphocyte culture, and the most sensitive indication of cytotoxic activity provided by inhibition of amino-acid incorporation and by loss of viable L cells from monolayers in tube cultures. In dilutions greater than 1:16-1:32 both cytotoxic supernatants exhibited a stimulating effect on target-cell proliferation. Stimulation of L cells growth was also observed when monolayers were exposed for 24 h to 'early' (24 h) PHA undiluted supernatants, At a later time of exposure to these supernatants a considerable loss of total and viable cells in the monolayers was evident. The results indicated that both cytotoxic and growth-stimulating lymphokines could be generated during activation of rat lymphocytes. A hypothesis is suggested whereby `lymphotoxin' activity in vitro arises from the sequential effects of stimulating and cytotoxic lymphokine, and whereby the balance of these effects in vivo might determine the response of fibroblasts involved in reactions of chronic allergic inflammation. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate whether an antibody directed against the exocrine secretion, saliva, is able to induce a modification in vivo within the specific cells of the submaxillary glands which synthesize this secretion. The salivary antigens synthesized within the glandular acinar cells are secreted into they respective lumen and are not present in the general circulation or in the intercellular spaces of the gland. When heterologous anti-saliva antibodies are injected into mice, they induce marked lesions within the acinar cells of the submaxillary glands. When different antibodies recognizing different salivary components are injected, they ail induce similar modifications; it is not yet possible to distinguish whether different cells are involved in the synthesis of the different salivary components. The lesions described seem specific since other organs studied, such as the pancreas and the stomach, are unaffected. The different possible mechanisms of this cytotoxic effect are discussed. [ABSTRACT FROM AUTHOR]

This paper describes the application of numerical methods to the arrangement of four leishmanial strains according to their reactivity and cross-reactivity in tests of parasite agglutination, indirect immunofluorescence and passive cutaneous anaphylaxis with antisera prepared by immunization or infection of rabbits, guinea-pigs and mice. Using corresponding pools of animal sera as test 'reagents' the antigenic reactivity of the four leishmanial strains (L. enriettii, L. tropica major, L. aethiopica and L. mexicana amazonensis) was scaled by reference to end point serum titres; and antigenic relationships between individual strain pairs were expressed as mean similarity coefficients, giving equal weight to the results of the different serological tests. Overall analysis of the results revealed that L. mexicana amazonensis and L. tropica major were the two most closely related strains, clustering with an overall similarity coefficient of 89 per cent, whereas coefficients of similarity between other strain combinations fell between 75 and 80 per cent. Although different sera had different discriminatory capacity for the leishmanial strains, two combinations of serum reagent and test system yielded relationships between the four strains that most closely approximated to the overall values. These were: (a) immunofluorescence tests with mouse antisera; and (b) agglutination tests with selected rabbit antisera. The results illustrate the use of a number of immunological parameters in relatingmicro organisms of a given genus, and reveal a serological classification of the four leishmanial strains at variance with their geographical origin. [ABSTRACT FROM AUTHOR]

Sera from mice with large tumours from a variety of tissue types and sources have been shown to contain substances capable of suppressing the proliferative response of normal mouse lymphocytes to concanavalin A (Con A), bacterial endotoxin (LPS) and allogeneic cells. The present paper deals with studies on the nature of these inhibitory materials using mainly a methylcholanthreneinduced rhabdomyosarcoma in DBA/2J mice. It was found that a material responsible for inhibition of the Con A response eluted with immunoglobulins on Sephadex G-150 and eluted with monomeric immunoglobulin on Sephadex G-200. The component of tumour-bearer serum responsible for the suppression of the LPS response of normal lymphocytes eluted from Sephadex G-150 with the α and β globulins and albumin (molecular weight < 150,000). The immunoglobulin-containing serum fraction from tumour-bearing animals inhibited the mixed lymphocyte response, Con A response, and specific immune response to purified protein derivative (PPD) in allogeneic cell systems. It also inhibited the in vitro primary response of mouse cells to sheep red blood cells, and, to a lesser extent, the response to a T cell-independent antigen (DNP-dextran). The inhibitory activity continued to elute with monomeric IgG on Sephadex G-200 when columns were run in 1640 medium and adjusted to pH 2.5, indicating that an acid dissociable complex was not responsible for inhibitory activity. Inhibitor activity could be removed by absorption on immunoadsorbents containing goat anti-mouse immunoglobulin, and could be recovered by acid elution from the adsorbent. Inhibitor activity was not removed by immunoadsorption on columns prepared with antisera to chicken immunoglobulin. [ABSTRACT FROM AUTHOR]

For most antisera a linear relationship can be shown between log antigen concentration and the log concentration of antibody required to bind half the available antigen. This paper shows that the slope of this line, s, is related to the distribution of individual antibody clonotypes of different affinity. It is argued that the general form of the distribution approximates to exponential (rather than for example Gaussian) and that this indicates a requirement for some force to be exerted through the antigen-receptor bond in order to activate a B cell. An alternative parameter, A, which gives more weight to high affinity clonotypes, is offered in place of K0 as a measure of the avidity and biological effectiveness of an antiserum. [ABSTRACT FROM AUTHOR]

Dextran B1355 is a branched glucose polymer containing 57 per cent α1-6, 35 per cent α1-3 and 8 per cent α1-2/1-4 linkages. Direct PFC responses to B1355 can be measured with sheep RBC sensitized with its O-stearoyl or palmitoyl derivative, and, as shown by inhibition analysis, are specific for an epitope which is dependent on α1-3 linkages. B1355 is a potent imnunogen in BALB/c mice producing peak PFC levels which approach 106 per spleen following an optimal dose of 1mg. By contrast, the α1-3-linked epitope of B1355 is feebly tolerogenic, for even 10 mg still induces a strong initial response. Mice given 1-10 mg sustain PFC levels 1-2 log10 above background for several months, but do not respond further to restimulation. Full recovery is attained by their spleen cells within 1 week of transfer into irradiated recipients Deeper tolerance to this epitope was attained in vivo only when these larger doses of B1355 were injected during cyclophosphamide suppression. Two exceptions to this weak tolerogenicity were found. First, BALB/c spleen cells developed durable partial α1-3 tolerance following 2-hour incubation with B1355 in vitro. Second, CBA mice were fully tolerized by doses of 1 mg upwards. It is argued from these and other data In the accompanying papers that the relative resistance of BALB/c mice to induction of α1-3 tolerance is explicable neither as part of a more general phenomenon based on macrophage activity nor as due to an inadequate epitope density. A possible explanation based on features of the genetically determined high α1-3 responsiveness of BALB/c B cells is discussed.

This work concerns the involvement of brown adipose tissue in the immune system of the rat. Wistar rats were thymectomized, adipectomized (surgical extirpation of the interscapular brown adipose tissue), thymectornited and adipectomized, and. sham,operated at birth, only 8-week-old females being employed in the experiment The production of antibody to bovine serum albumin (BSA). and sheep red blood cells (SRBC), delayed skin reactions to BSA, rejection of thyroid allograft implanted under the kidney capsule, and development of experimental allergic encephalomyelitis were investigated. Neonatal adipectomy did not affect the production of anti-BSA and anti-SRBC antibodies. On the other hand, delayed skin reactions to BSA, rejection of thyroid allograft, and incidence and severity of allergic encephalomyelitis were much more pronounced In adipectomized animals. It has been postulated that the immune function of brown adipose tissue is an expression of the secretory activity of the tissue. Since the immunosuppressive effect of neonatal thymectomy on demyelinating disease was neutralized by neonatal adipectomy, and vice versa, and since thymectomy rendered ineffective the immunopotentiating influence of adipectomy on this disease, as demonstrated in thymo-adipectomized rats, it was concluded that the brown adipose tissue is a natural antagonist of the thymus in cell-mediated immunity. This paper also describes the extra thymuses which were situated in the vicinity of the thyroid and parathyroid lobes of 23.2 per cent of rats. [ABSTRACT FROM AUTHOR]

Brain and thymocytes of rats, mice and fowls have certain antigenic determinants in common, which are restricted to these tissues. Among these, strain-, as well as species- and non-species-specific determinants have been detected with allotypic and heterologous antisera, respectively. With regard to the identical distribution pattern of these three different types of determinants on brain, thymus and lymph nodes it was suggested that they might belong to a common antigenic system. Using the technique of antibody-induced antigen redistribution, it is shown in the present paper that these three determinants on the thymocyte surface share a common molecular basic structure. [ABSTRACT FROM AUTHOR]

A mean of 6.9 per cent of small lymphocytes in peripheral blood preparations and between 1.8 and 2.4 per cent of small lymphocytes in lymph node, spleen, bone marrow and thymus preparations from unimmunized guinea-pigs bound 125I-labelled purified protein derivative of mammalian tuberculin (mammalian PPD). The percentage of these cells fluctuated but did not alter substantially after immunization with BCG or with BCG emulsified with human thyroglobulin (HTg) in Freund's incomplete adjuvant (FIA). Blocking experiments indicated that the binding of 125I-labelled mammalian PPD was specific and there was tentative evidence that the lymphocyte receptors may be IgG. A comparison is drawn between the observed time course of 125I-labelled mammalian PPD- binding small lymphocytes and the response of lymphocytes sensitive to strong histocompatibility antigens, and it is proposed that the propensity of certain anti- gens to induce a delayed hypersensitivity-type response is related to the presence of substantial numbers of antigen-binding cells in unimmunized animals. A noteworthy incidental finding was an unexplained depression in the cellular and humoral responses to mammalian PPD in guinea-pigs that had been immunized with HTg-BCG-FIA emulsion. [ABSTRACT FROM AUTHOR]

Lymph node and spleen cells from normal mice were cultured for 3 days with polyoma virus-induced tumour, Ehrlich's ascites turnout or leukaemia L 1210 cells. This resulted in in vitro immunization of the lymphocytes, which were then transferred to irradiated target cells labelled with 51Cr. Normal, i.e. non-immune thioglycollate-stimulated peritoneal macrophages were also added to some tubes. Non-immune macrophages mixed with immunized lymphocytes showed a significantly increased ability to destroy tumour ceils as compared with macrophages in the absence of immunized lymphocytes. The immunized lymphocytes were almost entirely inactive alone. When the number of macrophages was kept constant the cytotoxicity was dependent on the number of viable immunized lymphocytes placed on the target cells. Immunized lymphocytes, in the presence of macrophages, only exhibited strong killing of the target cells against which they had been immunized; some lysis of ‘bystander’ cells was, however, seen provided specific target cells were present. Macrophage monolayers exposed to immunized lymphocytes upon contact with specific antigen became ‘armed’ and showed a significant cytotoxicity for specific target cells. When immunized lymphocytes and normal macrophages were treated with actinomycin D and puromycin, cytotoxicity was inhibited in the immunized lymphocytes but not in the macrophages. The possible mechanism of normal macrophage cooperation with immunized lymphocytes in the cytotoxic killing reaction is discussed. Results presented in this paper favour the view that immunologically specific cytophilic factor (presumptive cytophilic antibody) is involved in the macrophage-mediated cytotoxicity in the system studied. [ABSTRACT FROM AUTHOR]

As part of our current efforts to develop assays and reagents to study the immune system of marine mammals, and in view of the effort currently made to develop monoclonal antibodies to cell surface proteins of lymphocyte subsets in different species, the present paper reports on the characterization of a monoclonal antibody against the homologue of CD45R on cetacean lymphocytes. The specificity of this antibody has been characterized on the basis of immunoprecipitation of the antigen it recognized, immunoperoxidase staining on cetacean lymph node and thymus sections, as well as one and two-colour flow cytometric analysis of cetacean peripheral blood mononuclear cells and single-cell suspensions of thymus, lymph node and spleen. Anti-cetacean CD45R (F21.H) immunoprecipitated proteins of 180, 200 and 220×103 MW, with the 180×103 MW form being predominantly expressed on T cells and the 220×103 MW form expressed predominantly on B cells and thymocytes. F21.H labelled all B cells and a proportion of T cells on single-cell suspensions of spleen cells. CD45R- killer whale peripheral blood lymphocytes expressed a higher density of CD2 than CD45R+, a characteristic of memory T cells. Killer whale T lymphocytes also lost the expression of CD45R upon activation with concanavalin A (Con A) and phytohaemagglutinin (PHA). This is the first report of a monoclonal antibody to CD45R in cetaceans, and this antibody is foreseen as a possible valuable diagnostic and research tool to assess immune functions of captive and wild cetaceans as part of the evaluation of their health status. [ABSTRACT FROM AUTHOR]

This paper describes the results of immuno-histochemical staining for chicken mannan-binding lectin (MBL) in formalin-fixed tissue sections from non-infected chickens, and from chickens infected with infectious laryngotracheitis virus (ILTV) or infectious bursal disease virus (IBDV). In the non-infected chickens, MBL was detected in the cytoplasm of a few hepatocytes and in the germinal centres of the caecal tonsils, whereas sections of kidney, heart muscle, spleen, cerebrum, thymus, adrenal gland, bursa of Fabricius, bone marrow and trachea were without staining. In the ILTV-infected chickens, an intense staining reaction for MBL was detected in the cytoplasm of all hepatocytes and on the surface of, and inside, ILTV-infected cells. Also in the IBDV-infected chickens, an intense staining reaction for MBL was detected in the cytoplasm of all hepatocytes. No staining was seen in the follicles of the bursa of Fabricius, but MBL was present in non-identified cells in the interstitium, and in the cytoplasm of macrophage-like cells, located peripheral to the ellipsoid of the spleen. These findings indicate the liver as the primary site of MBL synthesis, and points to up-regulation as a result of the viral infections. The location outside the liver could indicate a role of MBL in the immune defence. [ABSTRACT FROM AUTHOR]

We have previously reported that T lymphocytes proliferating in vitro to the hapten trinitrochlorobenzene (TNCB) exhibit a very restricted Vβ gene usage and response to TNCB is limited to T-cell receptors (TCR) composed of Vβ8.2 in combination with Vα3.2, Vα8 and Vα10. This paper investigates the role played by T lymphocytes expressing the Vβ8.2 gene segment in the contact sensitivity (CS) reaction to TNCB in the intact mouse and in its passive transfer into naive recipient mice. Mice injected with monoclonal antibodies to Vβ8 are unable to develop CS upon immunization with TNCB and 4-day TNCB-immune lymph node cells from mice that had been depleted in vivo or in vitro of Vβ8+ T lymphocytes fail to transfer CS. However, when separated Vβ8+ and Vβ8- cells were used for passive transfer, it was found that Vβ8+ T lymphocytes failed to transfer CS when given alone to recipient mice and a Vβ8- population was absolutely required. Further analysis revealed that within the Vβ8- population, T lymphocytes expressing the γδ TCR were fundamental to allow transfer of the CS reaction. These γδ cells were found to be antigen non-specific, genetically unrestricted and to rearrange the Vγ3 gene segment. This indicates that transfer of the CS reaction requires cross-talk between Vβ8+ and γδ+ T lymphocytes, thus confirming our previous results obtained using TNCB-specific T-cell lines. Time–course experiments showed that Vβ8+ lymphocytes taken 4–24 days after immunization with TNCB were able to proliferate and produce interleukin-2 (IL-2) in response to the specific antigen in vitro. Similar time–course experiments were then undertaken using the passive transfer of the CS reaction system. The results obtained confirm that TNCB-specific... [ABSTRACT FROM AUTHOR]