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A list of forthcoming articles in the "Immunology" 2008 issue is presented.

The first paper in this series reported that it was possible to reconstitute the response of low concentrations of mouse spleen lymphocytes to concanavalin A (Con A) by adding small numbers of peritoneal exudate cells (PEC) to the cultures. In this paper it is shown that the role of the PEC in this system can be partially replaced by conditioned medium (CM) prepared from PEC cultures or completely replaced by CM taken from lymphocytes cultured at optimal concentration. These CM were inactive unless fresh Con A was added to the assay cultures. Activity was present in CM which was incubated with lymphocytes or PEC for the shortest possible time but maximal activity was found after 24 hr of incubation. Activity was also found in CM prepared in the absence of Con A. Only in the case of lymphocytes cultured at optimal concentration for 24 hr was there substantially more activity in the CM thus prepared if Con A was present. PEC preparations depleted of T lymphocytes produced as much activity in CM as the untreated control. CM produced by PEC was less sensitive to heat treatment or to freezing and thawing than that produced by lymphocyte cultures. [ABSTRACT FROM AUTHOR]

Surfactant protein D (SP-D) is a collectin believed to play an important role in innate immunity. SP-D is characterized by having a collagen-like domain and a carbohydrate recognition domain (CRD), which has a specific Ca2+-dependent specificity for saccharides and thus the ability to bind complex glycoconjugates on micro-organisms. This paper describes the tissue immunolocalization of porcine SP-D (pSP-D) in normal slaughter pigs using a monoclonal antibody raised against purified pSP-D. Porcine SP-D was purified from porcine bronchoalveolar lavage (BAL) by maltose-agarose and immunoglobulin M affinity chromatography. The purified protein appeared on sodium dodecyl sulphate–polyacrylamide gel electrophoresis as a band of∼53 000 MW in the reduced state and∼138 000 MW in the unreduced state. Porcine SP-D was sensitive to collagenase digestion and N-deglycosylation, which reduced the molecular mass to∼24 000 MW and∼48 000 MW respectively, in the reduced state. N-deglycosylation of the collagen-resistant fragment, reduced the molecular mass to∼21 000 MW showing the presence of an N-glycosylation site located in the CRD. Porcine SP-D bound to solid-phase mannan in a dose and Ca2+-dependent manner with a saccharide specificity similar to rat and human SP-D. The purified protein was used for the production of a monoclonal anti-pSP-D antibody. The antibody reacted specifically with pSP-D in the reduced and unreduced state when analysed by Western blotting. Immunohistochemical evaluation of normal porcine tissues showed pSP-D immunoreactivity predominantly in Clara cells and serous cells of the bronchial submucosal glands, and to a lesser extent in alveolar type II cells, epithelial cells of the intestinal glands (crypts of Lieberkühn) in the duodenum, jejunum and ileum and serous cells of the dorsolateral lacrimal gland. [ABSTRACT FROM AUTHOR]

The expression of a diverse array of receptors for sulphated polysaccharides on lymphocytes has been demonstrated by Parish & Snowden (1985). This paper presents evidence to suggest that other cell types, namely macrophages, polymorphonuclear leucocytes, mast cells and fibroblasts, can bind similar polysaccharides. Using a rosetting assay and eleven structurally unique polysaccharides, each cell type was observed to bind a characteristic array of these polysaccharides. Analysis of the polysaccharide reactivity of macrophages revealed that BCG-activated and thioglycollate-elicited macrophages express an expanded repertoire of reactivity compared to resident peritoneal macrophages. For example, only thioglycollate-elicited macrophages, but not resident and BCG-activated peritoneal macrophages, reacted with the glycosaminoglycans, chondroitin-4-sulphate, chondroitin-6-sulphate and dermatan sulphate, while both BCG- and thioglycolate-activated, but not resident peritoneal macrophages, bound pentosan polysulphate-coupled sheep erythrocytes. The expression of the receptors for chondroitin-4- and -6-sulphate was observed to be cyclic and peaked at 2 and 5-6 days after thioglycollate treatment. Preliminary analyses of the functional significance of the observed binding of polysaccharides to macrophages revealed that heparin, fucoidan and kappa-carrageenen were specifically endocytosed. However, endocytosis of all other test polysaccharides was not observed. Finally, polysaccharide-coupled sheep erythrocytes were not phagocytosed, even though they interacted strongly with the macrophage surface. The possible relevance of these observations to an inflammatory response and as a means of identifying cellular subsets is discussed. [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]

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]

This paper examines helper T-cell responses and antibody titres and isotypes following immunization with a peptide antigen in association with three different adjuvants. B10.A mice were primed with pigeon cytochrome c fragment 81-104 in association with the adjuvants complete Freund's adjuvant (CFA), incomplete Freund's adjuvant (IFA) and alum. Strong antibody responses, dominated by IgG1, were observed upon priming with CFA and IFA. In contrast, priming with alum induced a weak antibody response with little or no detectable antigen-specific IgG1. These differences did not correlate with differences in T-cell priming, as immunization with peptide in association with all three adjuvants induced comparable T-cell proliferative responses and frequencies of antigen-specific cells. In addition, no significant differences in iiiterleukin-2 (IL-2), interferon-gamma (IFN-γ) and IL-4 production could be found, suggesting that the adjuvants did not differentially affect Th1 and Th2 cells. [ABSTRACT FROM AUTHOR]

The primary receptor ligand interaction between rat leucocyte membrane receptors for IgM and their ligands were examined. We found that the incubation time for optimal IgM binding is different on the two types of IgM-Fc receptor-bearing spleen cells and peritoneal macrophages. The investigation of cytophilic activity of polyclonal or monoclonal IgM proteins and their fragments from various species indicated the fine specificity of receptors. Finally, data arc presented which suggest a multiple point co-operative binding between IgM-coated erythrocytes and IgM-Fc receptor-bearing cells. [ABSTRACT FROM AUTHOR]

In normal CBA/H mice implanted under the kidney capsule with eight CBA/H.T6T6 neonatal thymus lobes it was observed that the percentage of marked thymus-graft derived T cells in the periphery, after building up to a peak, showed a biphasic exponential decline. The initial decline was very rapid and appeared to be due to loss of the thymus-graft derived cells from the system. The later decline was slower and was the same as that of an introduced cohort of lymph-node lymphocytes. The second rate of decline was, however, considerably more rapid than that of a lymph-node cohort in non thymus-grafted mice. We conclude that in multiply thymus-grafted mice the flow of cells through the T-cell pool is more rapid than in normal mice and that in this sense the thymus can be thought to drive the lymphoid system. [ABSTRACT FROM AUTHOR]

Human trophoblast cells express an unusual repertoire of human leucocyte antigen (HLA) molecules which has been difficult to define. Close homology between and extreme polymorphism at the classical HLA class-I (HLA-I) loci has made it difficult to generate locus-specific monoclonal antibodies (mAbs). The problem of defining an antibody’s reactivity against the thousands of existing HLA-I allotypes has often made it impossible to determine the HLA bound by a mAb in biological samples from a normal outbred population. Here we have used commercially available beads coated with individual HLA-I to characterize experimentally the reactivity of nine mAb against 96 common HLA-I allotypes. In conjunction with donor HLA-I genotyping, we could then define the specific HLA molecules bound by these antibodies in normal individuals. We used this approach to analyse the HLA expression of primary trophoblast cells from normal pregnancies; the choriocarcinoma cells JEG-3 and JAR; and the placental cell lines HTR-8/SVneo, Swan-71 and TEV-1. We confirm that primary villous trophoblast cells are HLA null whereas extravillous trophoblast cells express HLA-C, HLA-G and HLA-E, but not HLA-A, HLA-B or HLA-DR molecules in normal pregnancy. Tumour-derived JEG-3 and JAR cells reflect extravillous and villous trophoblast HLA phenotypes, respectively, but the HLA repertoire of the in vitro derived placental cell lines is not representative of either in vivo trophoblast phenotype. This study raises questions regarding the validity of using the placental cell lines that are currently available as model systems for immunological interactions between fetal trophoblast and maternal leucocytes bearing receptors for HLA molecules. [ABSTRACT FROM AUTHOR]

We studied the tolerization of neonatal thymocytes (NT), neonatal splenocytes (NS) and adult thymocytes (AT), transferred to syngeneic nude ( nu/nu) hosts previously injected with semi-allogeneic splenocytes, without any supportive immunosuppressive treatment. This protocol allows the study of peripheral tolerance in the absence of the thymus. BALB/c neonatal T cells and ATs were able to expand in syngeneic BALB/c nu/nu mice and functionally reconstituted an allogeneic response, rejecting (BALB/c × B6.Ba) F1 splenocytes transferred 3–4 weeks after injection of BALB/c cells. However, if (BALB/c × B6.Ba) F1 cells were injected into BALB/c nude hosts 30 days before transfer of NT, NS or AT cells, the F1 population was preserved and specific tolerance to B6 allografts was established. Furthermore, transfer to lymphopenic F1 nu/nu showed that tolerance could be established only for neonatal populations, showing that unique properties of neonatal T cells allow their tolerization in both lymphopenic and non-lymphopenic conditions, in the absence of suppressive immunotherapy. These results bring empirical support to the possibility of T-cell engraftment in immunodeficient patients showing partial identity with donor major histocompatibility complex (MHC) genes; the manipulation of immunological maturity of donor T cells may be the key for successful reconstitution of immunocompetence without induction of graft-versus-host disease. [ABSTRACT FROM AUTHOR]

Dendritic cells (DC) are sensitive to their local environment and are affected by proximal cell death. This study investigated the modulatory effect of cell death on DC function. Monocyte-derived DC exposed to apoptotic Jurkat or primary T cells failed to induce phenotypic maturation of the DC and were unable to support CD4+ allogeneic T-cell proliferation compared with DC exposed to lipopolysaccharide (LPS) or necrotic cells. Apoptotic cells coincubated with LPS- or necrotic cell-induced mature DC significantly suppressed CD80, CD86 and CD83 and attenuated LPS-induced CD4+ T-cell proliferation. Reduced levels of interleukin-12 (IL-12), IL-10, IL-6, tumour necrosis factor-α and interferon-γ (IFN-γ) were found to be concomitant with the suppressive activity of apoptotic cells upon DC. Furthermore, intracellular staining confirmed IFN-γ expression by DC in association with apoptotic environments. The specific generation of IFN-γ by DC within apoptotic environments is suggestive of an anti-inflammatory role by the induction of indoleamine 2,3-dioxygenase (IDO). Both neutralization of IFN-γ and IDO blockade demonstrated a role for IFN-γ and IDO in the suppression of CD4+ T cells. Moreover, we demonstrate that IDO expression within the DC was found to be IFN-γ-dependent. Blocking transforming growth factor-β (TGF-β) also produced a partial release in T-cell proliferation. Our study strongly suggests that apoptosis-induced DC suppression is not an immunological null event and two prime mediators underpinning these functional effects are IFN-γ-induced IDO and TGF-β. [ABSTRACT FROM AUTHOR]

Memory T-cell responses are faster and more robust than those of their naïve counterparts. The mechanisms by which memory T cells respond better to subsequent antigenic exposure remain unresolved. A portion of the more rapid response is undoubtedly the result of the increased frequency of antigen-specific cells. In addition, there are also differences in the cells themselves with respect to their requirements for costimulation and the apparent avidity of the T cells. We used major histocompatibility complex (MHC) class I tetramers to stimulate T cells to focus on the interaction of T-cell receptor (TCR)/MHC and CD8 in the absence of other molecules that are present on cell surfaces and so contribute to the activation of T cells by undefined mechanisms. Mutated MHC class I tetramers that are unable to engage CD8 were used to investigate the role of CD8 engagement in memory cell activation. Either wild-type tetramers or tetramers carrying the mutation were used to stimulate both memory and naïve TCR transgenic T cellsin vitro. Surprisingly, like naïve cells, memory CD8+ T cells required CD8 engagement for calcium mobilization and optimum proliferation. In contrast, the requirements for cytokine production differed. Unlike naive cells, memory cells were able to produce cytokine in the absence of CD8 engagement. This suggests both a CD8-dependent pathway for early events and a CD8-independent pathway for cytokine production in memory cells. [ABSTRACT FROM AUTHOR]

Summary We assessed whether antiretroviral regimes are able to diminish apoptosis and markers of lymphocyte activation and restore lymphocyte proliferation. T-cell subset, spontaneous and induced apoptosis, CD95 and soluble Fas antigen and cell proliferation were analysed in 41 human immunodeficiency virus type 1-positive patients. Twenty-five were in asymptomatic stage A and 16 were in stage B/C. Thirty-five received antiretroviral treatment: 18 received two inhibitors of reverse transcriptase and one protease inhibitor and 17 received three inhibitors of reverse transcriptase. Six patients did not receive treatment, for different reasons, but continued to participate in the study. Studies were performed at baseline, 3, 6 and 12 months. Levels of CD4 increased slightly until 6 months of antiretroviral treatment, as a whole, in all the patients treated. Naïve CD4 lymphocytes, as well as memory CD4 lymphocytes, remained constant. Spontaneous apoptosis of lymphocytes, after 72 hr of culture, decreased in all patients treated, but to a much smaller extent than phytohaemagglutinin-induced apoptosis. In both groups treated, levels of soluble Fas decreased until 6 months of treatment and then increased again. Lymphocyte proliferation reached normal levels after 1 year of treatment. In patients without treatment CD4 cells decreased slowly and no modification in activation markers was found. Antiretroviral regimes decrease immune activation as well as viral load and this deactivation restores lymphocyte proliferation. [ABSTRACT FROM AUTHOR]

In the present study, the genetic mechanisms responsible for generation of antibodies recognizing the dominant epitope within a synthetic peptide PS1CT3 were examined. PS1CT3 is a peptide model antigen containing residues 28–42 of the large protein of the surface antigen of hepatitis B virus as B epitope (designated PS1), and the known T-helper-cell epitope derived from the circumsporozoite protein of the malaria parasite Plasmodium falciparum (designated CT3). To characterize the repertoire generated, the immunoglobulin heavy chain variable regions from IgM and IgG monoclonal antibodies against PS1CT3 were sequenced. Although all IgG monoclonal antibodies were directed against the immunodominant epitope, the genetic elements used were diverse. Comparison of the sequence of germ line precursor IgM to a mature IgG revealed that during maturation of the primary IgM response only the heavy chain fragment of the antibody molecule underwent somatic mutation. [ABSTRACT FROM AUTHOR]

In this study the existence of mixed isotype AβbEαd molecules in Eαd gene-introduced C57BL/6 (B6Eαd) transgenic mice is demonstrated. Biosynthetically labelled B6Eαd transgenic spleen cells were immunoprecipitated with anti-Aβb or anti-Eαdmonoclonal antibody (mAb) and analysed by twodimensional gel electrophoresis (NEPHGE/SDS-PAGE). Anti-Aβb mAb precipitated Eαd molecules in addition to Aβb and Aαa molecules. Anti-Eα d mAb precipitated Aβbolecules in addition to Eβb and Eαd molecules. No Eαd mAb from B10.A(3R) spleen cells, which have a very similar organization of class II molecules to B6Eβb mAb from B10.A(3R) spleen cells, which have a very similar organization of class II molecules to B6Eαd transgenic mice. Since this B6Eαdtransgenic mouse was shown to have 20-40 copies per cell of the Eαd transgene (Kashiwamura et al., 1988), it is speculated that large amounts of Eαd transgene are made but, according to the data presented here, only a small amount actually associates with Aβb as opposed to Eβb. [ABSTRACT FROM AUTHOR]

Following lymphadenectomy, popliteal peripheral leucocytes present in afferent lymphatics draining the skin can be obtained relatively free of contaminating cells derived from blood and central lymph in contrast to prescapular and hepatic peripheral lymph which contain contaminating cells. Popliteal peripheral lymphocytes comprise a population of long-lived dividing cells that are deficient responders in mixed lymphocyte cultures (MLC) but elicit strong responses following stimulation with phorbol myristate acetate plus ionomycin or concanavalin A. Deficient responsiveness persisted when popliteal peripheral lymphocytes were cultured for 3 weeks prior to setting up MLC. The in vitro results correlate with in vivo results from normal lymphocyte transfer reactions and indicate that peripheral lymphocytes may comprise a population deficient in T-cell receptors mediating allogeneic stimulation. [ABSTRACT FROM AUTHOR]

An animal model was used to examine local and systemic cellular reactivity against virus infection of bowel mucosa. Firstly, existing techniques for extracting lymphoid cells from the dispersed populations of the bowel mucosa were adapted for use in rabbits and viable lymphocytes were isolated from the lapine ileal mucosa in numbers suitable for assay. Lamina propria lymphocytes (LPL) showed a strong blastogenic response to T-cell mitogens but intra-epithelial lymphocytes (JEL) responded poorly, even in the presence of splenic accessory cells. Next, chronically isolated deal loops in rabbits were infected with parainfluenzavirus type 3 (P1-3) and isolates from the organized and dispersed lymphoid tissues associated with infected ileal mucosac and those from systemic lymphoid sites were used in in vitro assays of virus-specific lympho-proliferation. A T-cell-mediated immune response against P1-3 was mounted in lymphoid tissues associated with the infected loops, appearing first in loop Peyer's patches (PP) at Day 4 and in mesenteric lymph nodes (MLN) and lamina propriae at Day 7 after infection. The response in PP had waned by 21 days but was sustained in the other sites for at least 42 days. Epithelial lymphocytes were consistently anergic and there was no evidence of specific reactivity at systemic lymphoid sites or elsewhere in the bowel. Thus, a highly localized T-cell-mediated response was sustained, not only in organized lymphoid tissues but also in the bowel wall itself, following infection with a novel antigen. [ABSTRACT FROM AUTHOR]

Decay-accelerating factor (DAF) is a 70,000 MW membrane protein that regulates the complement system on the cell surface. In the present study, we found that DAF had no affect on the classical pathway C3 and C5 convertases that had been stabilized by C4 nephritic factor (C4NeF). In DAF- incorporated cells, however, the assembly of the classical pathway C3 convertase was markedly inhibited even in the presence of C4NeF. C3 nephritic factor (C3NeF) in the alternative pathway protected the C3 convertase from the action of DAF to some extent, while the generation of C3 convertase was also inhibited by DAF. These results indicate that under physiological conditions, DAF functions to inhibit the assembly of C3 convertases even in the presence of nephritic factors. although it has no or little effect on the stabilized convertases. Thus, it is likely that DAF plays an important role in protection of host cells from damage by autologous complement in patients with nephritic factors. [ABSTRACT FROM AUTHOR]

Iris and ciliary body of mouse eyes have been examined for the presence of bone marrow-derived cells possessing the capability of functioning as antigen-presenting cells (APC). We have determined that iris and ciliary body contain significant numbers of cells bearing T200, indicating their bone marrow origin. Most of these express the F4/80 marker typically found on mature macrophages. However, approximately one-third of the cells express Ia and a similar number express Mac-1 markers. Virtually none of the cells express Thy-1 or surface immunoglobulin. Whole preparations of excised iris/ciliary body, or single cell suspensions prepared from these tissues were then assayed for their capacity to induce proliferation among allogeneic lymphocytes, it was discovered that iris/ciliary body tissues or cells did not function as alloantigen-presenting cells, although tissue and cells derived from the corneal limbus were allostimulatory. In addition, iris/ciliary body tissues and cells displayed the ablity to suppress mixed lymphocyte reactions to which they had been added as regulatory cells. We conclude that normal iris and ciliary body contain bone marrow-derived cells that fail to function as alloantigen-presenting cells. However, cells were present that have the capacity to inhibit alloimmune lymphocyte proliferation. The strategic location of inhibitory cells in the tissues that line the anterior chamber of the eye raises the possibility that these cells may play a role in the phenomenon of immunological privilege that is characteristic of this site. [ABSTRACT FROM AUTHOR]

In order to investigate the role of lymphocyte function-associated antigen 1 (LFA-1) in lymphocyte adhesion to endothelial cells (EC), we have studied the adhesion of a LFA-1-deficient lymphoblastoid cell line, ICH-KM, which has < 10% of the cell surface LFA-1 expressed on a normal lymphoblastoid cell line, ICH-BJ. The adhesion of ICH-KM cells to unstimulated EC was 49.9 ± 8-6% (mean ± SD) that of ICH-BJ cells. Moreover, phorbol ester-stimulated ICH-KM cells showed a considerably weaker increase in adhesion to unstimulated EC compared with ICH-BJ cells (mean ± SD increase in percentage adhesion, 3.8±2-3 compared with 18.5±8.0; P<0.025). In contrast, there was no significant difference between the enhanced adhesion of ICH-KM cells and ICH-BJ cells to interleukin-1 (IL-1)-stimulated EC. Thus ICH-KM cells showed a 22.7 ± 11.0 (mean ± SD) increase in percentage adhesion to IL-1-stimulated EC compared with the 24.8 ± 8-5 increase in percentage adhesion of ICH-BJ cells. Anti-LFA-1 monoclonal antibodies had no effect on the enhanced adhesion of ICH-KM and ICH-BJ cells to IL-1-stimulated EC but abolished the differences in adhesion between the two cell lines. The study therefore indicates that although a major part of unstimulated and phorbol ester-stimulated lymphocyte-EC adhesion is dependent upon LFA-1, the enhanced adhesion due to stimulation of EC with IL-1 is not dependent upon this molecule. The data therefore supports the existence of cytokine-inducible LFA-1-independent adhesion molecules for lymphocytes on EC. [ABSTRACT FROM AUTHOR]

We performed quantitative analysis of Eαd gene expression in the transgenic mice, created by microinjecting cloned Eαd gene fragments into C57BL/6 fertilized eggs. DNA dot-blot analysis revealed that Eαd gene-introduced transgenic mice (B6Eαd transgenic mice) contain 20 copies per cell of the Eαd gene in their genome. RNA dot-blot analysis revealed that the amount of Eαd mRNAs in B6Eαd transgenic spleen cells is 20-40-fold higher than those in normal BALB/c or (BALB × C578L/6)F1 (CEF1) spleen cells. However, the amount of Eαd molecules expressed on B6Eαd transgenic spleen cells was similar to that expressed on normal BALB/c of CBF1, spleen cells on a gene-dose basis. The amount of endogenous Eαd mRNA in the B6Eαd transgenic spleen cells was almost equal to that of normal B6 spleen cells. Since the cell surface I-E molecule is formed by non-covalent association of E. and E&beta chain, these results suggest that, in spite of the high expression of integrated Eαd gene in the cytoplasm of B6Eαd transgenic mice, the amount of Eαd gene expression on the cell surface is limited by the amount of endogenous Eαd gene products. [ABSTRACT FROM AUTHOR]

An immunohistochemical study of eosinophil distribution in the inflammatory cell infiltrates of four different types of myocardial lesions associated with Chaps' disease-caused by Trypanosoma cruzi-showed larger numbers of these cells in areas presenting tissue necrosis and degeneration, most notably in patients with the most severe myocarditis from a histopathological stand-point. Using antisera specific for human eosinophil-derived neurotoxin or eosinophil peroxidase, we detected deposits of these secretion products on myofibres and in the interstitium of chagasic myocardium displaying necrosis and degeneration but rarely in other types of lesions. These deposits were not detectable in the myocardium of non-chagasic patients who had died from myocardial infarction (acute or in the scarring stage) or myocarditis secondary to bacterial endocarditis. When human eosinophil-derived neurotoxin was incubated with myoblast monolayers there was significant cell injury, detachment and lysis. These effects were abrogated by yeast RNA, added as a competitive ribonuclease substrate, and inhibited by the ribonuclease inhibitor RNasin, suggesting that the ribonuclease activity of the eosinophil-derived neurotoxin was involved in the effect. These results suggest a link between eosinophil infiltration and necrosis in chagasic myocardial lesions and point to EDN, and perhaps other toxic eosinophil secretion products, as possible mediators of tissue damage. [ABSTRACT FROM AUTHOR]

Single-lung transplantation in the rat has been shown to provide an effective model for the study of cellular events associated with allograft rejection. It is possible to recover sufficient viable immune cells for functional immunological studies by lavage of the broncho--alveolar space of the grafts with tissue-culture medium. These cells are representative of the population within the parenchymal infiltrate, but are not exposed to harsh, potentially damaging, physical and chemical conditions during their extraction. Lavage-derived cells from non-immunosuppressed recipients showed donor-specific cytotoxicity, were clonable by limiting dilution culture, and proliferated in response to 24-hr stimulation with recombinant IL-2. Administration of Cyclosporin A (CsA) prevented pulmonary rejection and was also shown to block the formation of specific cytotoxic effector cells and the development of responsiveness to IL-2. [ABSTRACT FROM AUTHOR]

Retinoic add (RA) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) induce the capability to phagocytose heat-killed yeast (Y) (Saccharomyces cereviciae) in P388D1 cells. Y phagocytosis is specifically inhibited (100%) by particulate and soluble β-1,3-D-glucan. Other polysaccharides, such as agarose, dextran and dextran sulphate, are not inhibitory. The inhibitory capacity of mannan was totally abrogated by treatment with β-glucanase, suggesting that its activity is derived from a residual β-glucan structure. Partial hydrolysis of glucan particles with formic acid yielded soluble glucan that was fractionated according to size. Glucan¹, glucan² and glucan³ had an average chain length of 34, 23.5 and 15.5 glucose units, respectively. Fifty percent inhibition of Y phagocytosis by RA-P388D1 cells was attained at <0.02 μg/ml (∼ 2 nM) glucan¹ and at 1.1 μg/ml glucan³. A further decrease in chain length (≦ 12.6) resulted in oligomers of marginal inhibitory activity. Preincubation of RA- and 1,25(OH)2D3-P388D1 cells with glucan¹ for 30 seconds to 5 min, at 4° or 37°, followed by washes with buffer, sufficed to bring about 85-95% inhibition of Y phagocytosis. Recovery of the phagocytic capability was time dependent and required protein synthesis, suggesting a glucan¹-induced removal of membrane receptors. The results suggest that recognition and ingestion of Y by RA- or 1,25(OH)2D3-treated P388D1 cells depends almost exlusively on a β-glucan-specific receptor. [ABSTRACT FROM AUTHOR]

The helper function of human T4+ cells acting on autologous B cells, in the presence of monocytce-enriched cells (MEC), has been studied using the hapten--carrier conjugate DNP--streptococcal antigen (DNP-SA). The antibody response can be suppressed by T8+ cells, but selection of a Vicia villosa lectin-non-adherent (T8VV-) subset enhances the suppresor function. The T8 Vicia villosa lectin-adherent (T8VV+) cells are not suppressive, rather they inhibit the T8VV- cell suppressor function. Sequential reconstitution studies suggest that the target of both T8VV- suppressor-cell and T8VV+ contrasuppressor activity is the T4 helper-inducer cell. This was established after the separation of T4+ cells into Leu 8- helper- and Leu 8+ suppressor-inducer cells. Activation of T8VV- and T8VV+ cells with antigen before reconstitution with fresh lymphocytes and MEC suggests that T8VV- suppressor activity is antigen specific, whereas T8VV+ cell contrasuppressor function is non-specific. We suggest that the human T8+ cells are functionally heterogeneous and consist not only of suppressor and cytotoxic cells but also contrasuppressor cells. [ABSTRACT FROM AUTHOR]

Spleen cells from MRL-lpr/lpr, CBA and BALB/c mice were cultured in vitro and assayed for production of anti-nuclear antibodies. Spleen cells from all species produced IgM antibodies to a nRNP (Ul-RNP)-specific antigen and to double-stranded DNA (dsDNA) after stimulation with LPS. The specificity of the anti-nRNP antibodies was shown, by immunoblotting, to be directed against the 33,000 MW polypeptide of nRNP/Sm. CBA mice produced more IgM autoantibody in vitro than MRL/lpr or BALB/c mice. In contrast, IgG anti-nRNP and anti-dsDNA antibody were not produced by any of the strains. Our data show that anti-nRNP and anti-dsDNA precursor B cells are part of the normal murine immune repertoire and are not confined to the MRL/lpr strain. This suggests that the spontaneous development of anti-nRNP and anti-dsDNA antibodies associated with systemic lupus erythematosis (SLE) is dependent on clonal stimulation and removal of suppressive influences. [ABSTRACT FROM AUTHOR]

Ponies, without evidence of previous exposure to Equine herpes virus-1 (EHV-1), were experimentally infected with EHV-1I subtype 2 and investigated for lymphocyte transformation to virus-infected cell polypeptides, as shown by separation with gel electrophoresis. Animals made significant responses to Western blot fractions that corresponded to molecular weights of approximately 30,000, 40,000-45,000, 60,000-65,000, 80,000-95,000 and 100,000-140,000 MW. These molecular weight ranges correlated with the positions of major EHV-1 subtype 2 glycoproteins that were found at migration distances approximating to 137,000, 111,000, 90,000, 65,000 and 47,000 MW. Responses were also made to a subset of similar points on the subtype 1 profile. Hyperimmune equine serum precipitated numerous infected-cell proteins of both subtypes; in particular the recognition of polypeptides with MW of 142,000, 132,000, 114,000 and 46,000 was in agreement with the mitogenic responses. Labelling with 125I indicated that immunoprecipitated > 250,000, 182,000, 142,000, 132,000, 75,000, 46,000 and 32,000/34,000 MW products were exposed on the surface of infected cells. [ABSTRACT FROM AUTHOR]

The activities of two forms (7.5 and 5.5 S) of DNA ligase and of terminal deoxynucleotidyl transferase (TdT) have been studied in human thymocytes at different ages from 20 weeks pre-natal to 37 years after birth. Thymocytes have been selected on the basis of relative size and antigenicity (CD3, OKT3 immunofluorescence) with the cell sorter. For DNA ligases, three kinds of cells can be distinguished: (i) large antigenically negative cells of 20-week fetus, expressing only the 7.5 S enzyme; (ii) large antigenically positive cells without ligase activity; (iii) smaller antigenically positive cells, expressing only the 5.5 S enzyme. This last form of enzyme is found after birth. With respect to TdT expressed in OKT3- 5 μm cells and to OKT3+ thymocytes, it is observed that 5.5 S DNA ligase is found in a thymocyte population distinct from cells expressing TdT. Therefore, these results allow us to consider the 5.5 S DNA ligase activity as an additional functional marker for thymocyte maturation in humans. [ABSTRACT FROM AUTHOR]

The OKT3 antibody activates locomotion of human blood I lymphocytes as measured by polarization assays and invasion of collagen gels. The proportion of motile cells increases during a period of 24-48 hr of culture, even following only a brief initial contact with OKT3. The motile cells are the growing population. Locomotion activation is cell-density dependent. Studies with surface- bound mitogens, namely substratum-bound 0K13 and Con A-Sepharose, showed that only lymphocytes in direct contact with the mitogen acquired locomotor capacity. Those separated from it by a cell-impermeable filter were not activated. The response to OKT3 requires the whole antibody molecule. F(ab')2 fragments were inactive. Intact normal human IgG, but not its F(ab')2 fragments, blocked the response. Removal of RFcγ + cells from the population by rosetting with IgG-Ab-coated sheep red cells prevented the response. These findings suggest that an RFcγ + population has to be present for T cells to become activated to locomotion by OKT3, and that the OKT3 antibody links the T cell to an FcR + cell, cell-to-cell contact being essential for activating the locomotor response. [ABSTRACT FROM AUTHOR]

The role of suppressor cells in control of persistent infections may be of profound importance. Whether a positive immune response or suppression of immunity is generated at the time of initial exposure to pathogens causing such infections may in part be due to the nature of the initial antigen presentation to the specific cells of the immune system. We have shown that in vivo modulation of epidermal APCs by an environmentally encountered stimulus (UV-B light exposure) and subsequent transfer of these APCs together with live HSV-1 to naive syngeneic recipients is sufficient to generate suppression of DH rather than DH to HSV-1. This suppression is T-cell mediated and specific for HSV-l. The phenotype of the Ts cell induced by epidermal cell transfer is Thyl+ L3T4+ Ly2-. [ABSTRACT FROM AUTHOR]

Certain normal human peripheral blood lymphocyte (PBL) membrane receptors for the Fc region of IgG (i.e. Fey receptors) are known to be released spontaneously when incubated at 37° in serum-free medium into the culture supernatant. However, the mechanisms involved in spontaneous Fey receptor release are not clear. In this study we have shown that Fey receptors appear to be released in two stages. Stage I occurs within the first hour of incubation, and is probably mediated by limited proteolysis at the cell surface. Stage 2 occurs between 2 hr and 4 hr, and requires active synthesis of Fey receptors. The kinetics of Fey receptor release from activated PBL was found to be slightly different from normal, but no appreciable increase in Fey receptor 'activity' was found in the culture supernatants when compared with supernatants from normal 'resting' cells. It is doubtful whether these mechanisms operate in vivo since spontaneous release of Fey receptors was completely inhibited in the presence of serum. The serum factors that prevent receptor release were found to be confined to two distinct fractions corresponding to those that contain the major serum protease enzyme inhibitors-α2-macroglobulin and α1-trypsin inhibitor. [ABSTRACT FROM AUTHOR]

The role of L3T4 antigens in the concanavalin A (Con A) response of regenerating spleen cells (Cy-SCs) after cyclophosphamide (Cy) treatment was studied. Anti-L3T4 monoclonal antibodies (Mabs) markedly inhibited the Con A response of the regenerating Cy-SCs, which do not require Ia molecules expressed on accessory cells (ACs) for Con A activation. However, the Con A response of normal spleen cells (N-SCs), which do require Ia molecules on ACs, was not inhibited by the same Mabs, although the Con A response of N-SCs, as well as that of Cy-SCs, was demonstrated to be mediated by L3T4+ T cells. The optimal times for the inhibitory effect of anti-L3T4 Mab was 7 days after Cy treatment, when the number of spleen cells increased to a maximum following a regenerative phase. Its inhibitory effect was reduced by high concentrations of Con A, and was restricted to the early phase of the Con A response. A short time exposure of the Cy-SCs to the anti-L3T4 Mabs was sufficient to decrease the response to Con A. Our results cannot explain the hypothesis that the L3T4 molecule functions solely by interacting with non-polymorphic parts of Ia molecules on ACs Taken together, these results and those of other groups of investigators suggest that Con A-induced T-cell activation may be mediated by at least two or more interaction mechanisms involving either Ia or L3T4 molecules. Firstly, normal L3T4+ T cells may mainly interact with Con A involving self Ia molecules on the ACs. The extent of this interaction is sufficient to induce T-cell activation, and then does not need another L3T4 molecule. Secondly, the regenerating L3T4+ T cells may usually internet with the cell surface antigens of other T cells, including L3T4, by the binding of both cell surface molecules to Con A in the absence of ACs, and then transmit a signal for 1-cell activation. Anti-L3T4 Mabs may exert inhibitory effects somewhere in this process. [ABSTRACT FROM AUTHOR]

The present study indicates that two Mab specific to Fc∊R (MabER) on human B lymphocytes also react with Fc∊R on macrophage and T-cell lines. More importantly, it is also shown that MabER cross-react with IgE-BFs derived from B, T and macrophage cell lines. This conclusion is supported by the following observations: (i) the binding of MabER to Fc∊R-bearing cells is blocked by the CSN of T, B and macrophage Fc∊R-bearing cell lines, known to contain IgE-BFs as shown by their inhibition of rosette formation between IgE-coated erythrocytes and Fc∊R-bearing cells; (ii) the material purified from the CSN of each Fc∊R( +) cell lines by affinity chromatography on MabER-Affi-gel blocks the rosetting of U937 cells with IgE but not with IgG-coated erythrocytes; (iii) the same affinity-purified material inhibits the binding of 125I-IgE to a selected anti-IgE Mab (Mab 75); and (iv) the CSN of Fc∊R( +) cells but not of Fc∊R(-) cells reacts in a solid-phase sandwich radioimmunoassay with two MabER (135-176). and their reactivity is significantly retained on IgE-Affi-gel from which it may be recovered by glycine elution. This RIA is not influenced by any class of Ig, including IgE, employed at a final concentration of 100 μg/ml. Human serum also reacts in the RIA, and parellel dilution curves are obtained with different CSN and human sera. The RIA proved to be a reproducible and sensitive method to quantify human IgE-BFs. The expression of the same antigenic determinants on Fc∊R from T, B and macrophages as well as on the IgE-BFs secreted by these cells indicates structural homology between IgE receptors and IgE-FBs and suggests that they are encoded by the same gene. [ABSTRACT FROM AUTHOR]

A mouse monoclonal (Mab.198, IgGl) was generated that recognizes an epitope expressed on rabbit peripheral phagocytes and tissue macrophages. The membrane antigen recognized by Mab.198 consisted of two polypeptide chains of 165,000 and 95,000 molecular weight (MW). This Mab efficiently inhibited complement receptor-mediated granulocyte functions such as phagocytosis of complement-opsonized particulate antigens and zymosan-induced chemiluminescent responses. Fc receptor-mediated phagocyte functions were, on the contrary, barely affected by Mab.198. The cellular distribution, molecular structure and functional characteristics of the membrane antigen defined by Mab.198 suggested that this antibody recognizes the complement type 3 receptor (CR3). We found that Mab.MI/70, specific for mouse CR3 (i.e. CD 11 or Mac-1 antigen), also binds on rabbit phagocytes. However, this Mab recognizes a different CR3 epitope than Mab.198 as shown by cross-blocking experiments. This anti-rabbit CR3 Mab will be useful in the characterization of rabbit complement receptors and their involvement in immune reactions. [ABSTRACT FROM AUTHOR]

Affinity maturation was studied by the analysis of the kinetics of the appearance of antibody subpopulations with different affinities during the immune response, using an hapten-inhibition ELISA. The immune response in KLH-Ar-immunized A/J mice was used as a model system. Five antibody subpopulations of different affinity (103-107 M-1) could be detected, the relative concentrations of which changed during affinity maturation. The high-affinity antibody subpopulations did not represent the major fraction at any stage during affinity maturation. The appearance of the highest affinity subpopulation (107 M-1), despite exhibiting relative concentrations no higher than 12%, produced an important increase in average affinity. On the other hand, its disappearance at the end of the maturation process could explain the average affinity decrease observed at this stage. Our results indicate that affinity maturation cannot be explained by the dominance of high-affinity clones, as proposed by Siskind & Benacerraf (1969). The increase in affinity could rather be due to the progressive appearance of low percentages of high-affinity clones, which are not present in the primary response and never become dominant. [ABSTRACT FROM AUTHOR]

The idiotypic profile of anti-phosphorylcholine plaque-forming cell responses and their evolution with ageing were studied in (NZB × NZW) F1 mice. Our results showed that the anti-phosphorylcholine plaque-forming cell response induced by phosphorylcholine coupled to keyhole limpet haemocyanin and, paralleling, the T15 idiotype clonal dominance declined with ageing. This loss of immune competence was also observed with another thymus-dependant (phosphorylcholine coupled to egg globulin) as well as thymus-independent (capsular polysaccharide of Streptococcus pneumoniae strain R36a) antigens. In contrast, old mice challenged with an antigenic preparation of Neisseria meningitidis showed an immune response not significantly different from that elicited by the same antigen in young mice. The hapten-augmentable plaque-forming cells were assayed to determine whether a putative auto-antiidiotypic regulation underlies this loss of immune competence. Only minimal numbers and non-significant differences between young and old mice immunized with any antigen could be detected. Further studies using an adoptive transfer system demonstrated that cells from aged mice were able to support a normal anti-phosphorylcholine response when transferred into lethally irradiated young recipients. Our results suggest that no permanent cellular defects, but rather internal environment or/and radioresistant suppressor cells, are involved in this loss of immune competence. The role played by these factors and their effect on distinct subpopulations of B cells are discussed. [ABSTRACT FROM AUTHOR]

The induction of oral tolerance after ingestion of antigen has been reported in several animal models. The precise mechanisms responsible for this unresponsiveness are not well understood. As some investigations have suggested a key role of Peyer's patches suppressor T cells, an animal model was developed in which the PP were surgically removed. Using this model, the influence of the PP on the induction of oral tolerance against SRBC was investigated. In order to induce tolerance, the rats were fed SRBC on four consecutive days. On Day 5 they were i.p. challenged by injection of SRBC, and 5 days later the number of immunoglobulin-secreting cells against SRBC was determined within the spleen. Using this protocol, the oral tolerance induction could be shown very clearly in control animals as well as in rats without PP. Therefore, tolerance induction is possible in the absence of PP-T cells. Other mechanisms must be responsible for the tolerance induction in this model. [ABSTRACT FROM AUTHOR]

The response of primed T cells to keyhole limpet haemocyanin (KLH) was used to compare the characteristics of antigen presentation by lymphoid dendritic cells, splenic and peritoneal macrophages. In a similar manner to macrophages, purified dendritic cells could be pulsed with antigen and subsequently fixed by brief glutaraldehyde fixation and still retain antigen presenting activity. Also, as previously reported for macrophages, presentation could be inhibited by chloroquine. These functional experiments suggested that the pathway of antigen presentation in dendritic cells and macrophages was similar or identical. However, biochemical studies, using radiolabelled antigen, showed that dendritic cells do not significantly degrade large proteins such as KLH to TCA-soluble form, but partially hydrolyse them to smaller peptide fragments. The significance of these results in terms of a model of the cellular pathways of antigen presentation is discussed. [ABSTRACT FROM AUTHOR]

Binding of an antibody to an effector protein will not necessarily inactivate it totally. In order to incorporate this into mathematical expressions of neutralization reaction between a monoclonal antibody and an effector which acts on cells through receptor binding, a static equilibrium system was considered that consists of effector, receptor and antibody, allowing formation of the ternary complex. A formula was derived for the antibody dose-dependence of neutralization, which was qualitatively similar to that found experimentally for monoclonal antibodies to interferon. According to the formula, the extent of neutralization, N, will approach a saturation value N∞ at high antibody concentrations, instead of increasing indefinitely, as is the case with conventional antibodies; the value Nα is determined by the degree of reduction, upon antibody binding, of the effector's affinity to the receptor (and/or by the ability of antibody to inhibit the effector action subsequent to receptor binding). On the other hand, experimental data in the region of small N's will allow one to estimate the effector-antibody association constant. [ABSTRACT FROM AUTHOR]

The stimulating potential of freshly irradiated spleen cells in the generation of primary allogeneic cytolytic T lymphocytes (CTLs) is abrogated with as low as 0003% glutaraldehyde concentration, while their antigenicity begins to decrease only with 01%. We show here that the very high stimulating potential of murine radioresistant spleen cells (RSCs) in the primary allo-CTL generation is thirty times more resistant to glutaraldehyde than the one of total spleen cells, while the resistance of their antigenicity is similar. Analysis of the components of the resistance of RSC immunogenicity during MLC showed that IL- I activity produced by RSCs also decreases after 01% glutaraldehyde, and withstands cyclosporin A inhibition to a higher degree than fresh spleen cells. [ABSTRACT FROM AUTHOR]

Incorporation of lipid A into liposomes markedly enhances the plaque-forming cell (PFC responses against model membranes that are sensitized with synthetic amphipathic antigens 2,4-dinitrophenyl-6-N-aminocaproyldipalmytoylphosphatidylethanolamine (DNP-Cap-DPPE) and fluorescein thiocarbamyldipalmytoylphosphatidylethanolamine (FI-DPPE). The enhancing effect was pronounced only when lipid A and haptenic determinants were presented on the same liposome. Lipid A was incorporated into heterologous erythrocytes and syngeneic tumour cells. Significant and selective increase of in-vitro PFC responses was observed against heterologous erythrocytes, and immunization of C578L/6 mice with lipid A treated X-irradiated tumour cells (EL-4) markedly prolonged the survival of mice after challenge with homologous viable tumour cells. These data suggest that passively incorporated lipid A will be an effective method for selectively augmenting antibody formation against membrane-associated antigens. [ABSTRACT FROM AUTHOR]

The influence of antibody isotype on the lifetime of complexes involving cell surface antigens of the rat fibrosarcoma HSN.TC has been investigated using direct binding and competitive RIAs to monitor the antibodies. Alloantibodies of the lgG class that had bound to the cells during a 1-hr exposure to antiserum were cleared subsequently from the cell surface by an active process involving two distinct phases. Between 30 and 70% of these antibodies were lost in the first 10 hr but the antibodies remaining were cleared more slowly with half-lives ranging from 20 to 40 hr. Antibodies of the 1gM class, however, and those that could bind Clq and initiate the complement cascade were cleared rapidly with half-lives of less than 3 hr. Analysis of total cell-associated immunoglobulin showed that the disappearance from the cell surface was not a consequence of intracellular accumulation of antibody but was caused by the release of the antibody in a degraded form. The surface expression of the majority of the alloantigens involved was not affected by continuous exposure to antibody although modulation of a subpopulation of antigens could not be excluded. These results suggest that the clearance of alloantibodies involved their internalization and degradation and that antibodies capable of forming multimeric complexes were cleared rapidly. Some of the lgG-containing complexes, however, exhibited extended lifetimes at the cell surface, suggesting that either they were not internalized or they were recycled between the cell interior and the plasma membrane. [ABSTRACT FROM AUTHOR]

Cytotoxic T cells that arise spontaneously in cultures (SCTL) appear to be distinct from natural killer (NK) cells. The specificity of these two types of cytotoxic cell populations has been compared by direct cytotoxicity and cold target inhibition tests. The SCTL population consists of an array of cytotoxic cells each of which is specific for a series of target cells. The NK cells had a more limited range of target selectivity although at least two types of NK effector cells were detected on the basis of specificity measurements. [ABSTRACT FROM AUTHOR]

The effects of human α2 macroglobulin (α2M) on locomotion of human neutrophils and monocytes in micropore filter assays in vitro were studied. Native α2M had no effect on cell locomotion. In contrast, α2M which had been modified by interaction with proteases (trypsin, collagenase), or with ammonium sulphate, stimulated locomotion of both cell types. The degree of locomotory response induced in the cells by α2M correlated closely with changes in molecular conformation of α2M as estimated by measurements of binding of the fluorescent probe, l-anilinonaphthalene-8-sulphonic acid (ANS). However neutrophil locomotion stimulated by modified α2M appeared to be solely chemokinetic, whereas monocytes showed both chemokinetic and chemotactic responses to modified α2M. The reason for this difference in response between the two cell types is unclear, but it is reflected in the lack of specific binding of α2M-protease complexes by neutrophils. Earlier workers had shown specific binding of such complexes by mononuclear phagocytes. [ABSTRACT FROM AUTHOR]

The effect of pregnancy on the immune status of CBA mice has been measured in terms of Ig-secreting cells. Reversed plaque assays show that there is a considerable increase in numbers of IgG- and, to a lesser extent, IgM-secreting cells in the para-aortic lymph nodes. Similar but muted response were observed in the spleen and among the lymphocytes of the peripheral blood. Analysis of cells sorted for intensity of staining for surface Ig in a fluorescence-activated cell sorter (FACS), shows that Ig-secreting cells are confined to a population of very weakly staining cells. The 'response' in syngeneic pregnancies (CBA × CBA) is at least as great as that seen in allogeneic pregnancies (CBA × C57). Active immunity to a xenogeneic erythrocyte antigen is potentiated by pregnancy. [ABSTRACT FROM AUTHOR]

Guinea-pig line 10 tumor (GPL10) cells, which were transplantable in strain 2 guinea-pigs, gained the capacity to activate the homologous alternative complement pathway (ACP) following infection with ultraviolet-irradiated Sendai virus (UV-SV). The ACP activation of homologous serum on the UV-SV-infected GPL10 cells (UV-SV-GPL10 cells) resulted in cytolysis of the tumor cells. This indicates that UV-SV infection induced not only the capacity to activate complement on the GPL10 cells, but also made them sensitive to complement attack, because GPL 10 cells have been demonstrated to be resistant to the reaction of homologous complement via the classical pathway in the presence of rabbit antibody. Furthermore, UV-SV-GPL10 cells prepared with as little as 0·1 plaque-forming unit equivalent of UV-SV per cell showed suppressed growth in syngeneic strain 2 guinea-pigs. The essential rote of complement in the elimination of UV-SV-GPLI0 cells m vivo was confirmed by demonstrating that UV-SV-GPLI0 could grow in guinea-pigs whose complement had been depleted by administraton of cobra venom factor. [ABSTRACT FROM AUTHOR]

A large number of cells which can replicate vesicular stomatitis virus (VSV) were generated in pokeweed mitogen (PWM)-stimulated cultures of normal mouse spleen cells. The optimal dose of PWM for the generation of VSV-replicating cells was within the range 25 and 50 µg/ml, which had previously been shown to be optimal for the induction of suppressor cells. The VSV-replicating cells in this system were shown to be Thy 1+ and Lyt 1+2-. These cells, however, were unlikely to be helper T cells, but may be a subset of T cells involved in suppression. Thus, inoculation of VSV into a PWM-stimulated culture of spleen cells resulted in marked augmentation of polyclonal immunoglobulin production. Further, it was shown that the suppressive activity of T cells which had been precultured with a high dose of PWM was abolished by the infection with this virus. [ABSTRACT FROM AUTHOR]

In plasma clots the presence of ferritin-anti-ferritin complexes interferes with the bactericidal power of polymorphs against Klebsiella pneumoniae and Escherichia coli. Equivalent concentrations of apoferritin-antiferritin complexes, which lack Fe, do not have this effect and it is therefore suggested that the iron-binding capacity of lactoferrin in polymorphs plays an essential role in the bactericidal power of the cell. Similar results were obtained in vivo where ferritin- antiferritin complexes cause a high mortality in other- wise non-lethal infections. Evidence suggests that it is the iron in the ferritin which is responsible for the rapid intracellular bacterial growth and that lactoferrin normally plays an important protective role within the polymorphs. [ABSTRACT FROM AUTHOR]