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Cellular immune responsiveness, as measured by lymphocyte transformation in one-way mixed leucocyte cultures (MLC) and in phytohaemagglutinin (PHA) stimulated cultures was evaluated in forty patients with systemic lupus erythematosus (SLE) and in seventy-four normal controls. The effect produced by sera from these subjects on in vitro lymphocyte reactivity was tested on autologous cells and on homologous responding cells from a constant panel of ten healthy volunteers. The reactivity of lymphocytes from SLE patients to PHA and to a battery of allogeneic cells was significantly lower than that of normal controls. Sera from some SLE patients inhibited the MLC reactions, while in other cases a distinct stimulatory effect was found. It is suggested that virus-induced modifications of normal histocompatibility antigens cause the appearance of blocking antibody that might bind to the surface of T lymphocytes, impairing their function. [ABSTRACT FROM AUTHOR]

The cross-reactivity of heterologous erythrocytes was measured at the level of the B and the T cell. B cells produced antibody with restricted cross-reactivity as compared with the cross-reactivity of T cells, assayed by their ability to help B cells in a primary anti-sheep erythrocyte immune response. Helper function was maximally elicited with low antigen doses. The data suggest that the T-cell antigen receptors for erythrocyte antigens differ in specificity from those of B cells and that the sensitivity of T cells to antigen may be very great. [ABSTRACT FROM AUTHOR]

Production of antibody against major trasplantation antigens has been studied in sheep receiving osteoarticular allografts at the knee joint. These investigations have shown that this type of allograft leads to the rapid production of serum antibodies in the recipient animal. It was found that a high proportion of the sheep used in these studies possessed antibodies before operation. A large number of the animals which possessed antibody against major transplantation antigens prior to operation developed a wide spectrum of antibodies after operation more rapidly than did those recipients who had no pre-existing antibody. A smaller number showed an increase in antibody spectrum which was comparable with non-sensitized recipients. An analysis of the patters of antibody production was carried out in order to assess the possible benefits of reducing the bony component of the graft in lowering its immunogenicity. It was found that the thickness of bone carried by the graft was largely irrelevant and the immune response was initiated with only small amounts of bone. There is some evidence in this data that the surface area of bone is important in determining the pattern of the immune response. [ABSTRACT FROM AUTHOR]

Both the humoral and cellular immune response to haemocyanin was measured in normal subjects and patients with liver disease including primary biliary cirrhosis, other forms of cholestasis, and cryptogenic cirrhosis. Significant differences in antibody titre were found 2 weeks after immunization being highest in normal subjects, less in cryptogenic cirrhosis and least in primary biliary cirrhosis. The incidence of positive skin tests, indicating the development of delayed hypersensitivity to haemocyanin, was significantly less in patients with primary biliary cirrhosis and cryptogenic cirrhosis than in those with cholestasis or the normal subjects. It is suggested that the poor antibody response seen in primary biliary cirrhosis, could be related to impaired T cell function and hence lack of the T and B cell co-operation necessary for antibody formation to some antigens. The presence of delayed hypersensitivity to haemocyanin as measured by the skin test was compared to other tests of delayed hypersensitivity including the tuberculin skin test, DNCB sensitization and PHA-stimulated in vitro lymphocyte transformation. Of twenty patients with primary biliary cirrhosis the results of all four tests correlated in nine but did not agree in the remaining eleven patients. These results emphasize the importance of using a number of indices when assessing the degree of energy of any one patient. [ABSTRACT FROM AUTHOR]

Evidence is presented to substantiate an earlier report that macrophages are the operative cells in the initiation of lymphocyte trapping. Several procedures which increase phagocytosis in mice of a soluble antigen (BGG), including transfer of specific serum or of adherent and non-adherent immune cells, or the transfer of in vitro sensitized macrophages, enhance the trapping potential of BGG. Animals tolerant to BGG trapped effectively when challenged with aggregated BGG, or when passively immunized and challenged with soluble BGG. The trapping defect in tolerant animals is thus due to a specific defect in immune responsiveness rather than an inherent failure of the trap mechanism. The dissociation between trapping and immune responsiveness is discussed. [ABSTRACT FROM AUTHOR]

The effects of Ca++ on primary and secondary immune responses to SRBC in vitro was investigated using the Marbrook technique. During the primary immune response three periods could be distinguished: first, a Ca++-independent lag period (0-24 hours after antigenic stimulation); second, a period with an absolute requirement for Ca++ (24-36 hours after antigenic stimulation), which is related to a proliferative phase of antigenically stimulated cells; and third, a period (later than 48 hours and up to 72 hours after antigenic stimulation), which is inhibited by Ca++ and which can be enhanced by removing Ca++ from the medium. This third period is related to the differentiation step(s) leading to antibody-forming cells. During the secondary immune response only a partial inhibition of immune response was observed after removing Ca++ from the medium at the time of antigenic stimulation. Addition of Ca++ to EGTA-containing culture medium at any time relative to the initiation of the secondary immune response enhanced the response, but, in contrast to its effects on a primary immune response, never completely restored it. Removal of Ca++ later than 6 hours after initiation of the response resulted in a decreased inhibition of the immune response and in an increased switch from 19S to 7S antibody-forming cells. This differentiation step was enhanced by removing Ca++ from the medium and was inhibited by Ca++ added to the medium. The results suggest that Ca++ controls the mechanisms involved in the antibody formation by an antagonistic action on cell proliferation and cell differentiation. [ABSTRACT FROM AUTHOR]

Rabbit appendix cells were injected into horses at weekly intervals, after which the horses were bled and the sera tested for cytotoxic activity. The unabsorbed antiserum was cytotoxic to the lymphocytes of all the lymphoid organs tested Following absorption with bone marrow and thymus cells, the antiserum lost all cytotoxic activity directed toward these cells but displayed almost undiminished cytotoxic activity toward the cells of the SAPP organs (sacculus rotundus, appendix and Peyer's patches). The absorbed antiserum also demonstrated cytotoxic activity toward certain lymphocytes present in the spleen, lymph node and circulation. Thus, the antibodies directed toward the antigens common to all lymphoid cells were removed by the thymus and bone marrow cells, leaving behind cytotoxic antibodies directed toss aid antigens present on appendix and appendix-derived cells only, We have therefore succeeded in preparing antisera specific for rabbit thymus, bone marrow and appendix cells, respectively. [ABSTRACT FROM AUTHOR]

Horse anti-rabbit bone marrow cell antiserum was tested for its cytotoxic activity with respect to the lymphocytes of the various lymphoid organs. The unabsorbed antiserum was highly cytotoxic with respect to the circulating WBC and cells of the bone marrow and thymus but demonstrated low cytotoxic activity with respect to spleen, lymph node and SAPP cells (sacculus rotundus, appendix and Peyer's patches). However, following absorption with thymocytes, lymph node cells or SAPP cells, cytotoxic activity directed toward any of these cell types disappeared without affecting the cytotoxic activity with respect to bone marrow and circulating lymphocytes. On the other hand, bone marrow and spleen cells and circulating white blood cells were capable of absorbing out completely the cytotoxic activity directed toward these cells, On the basis of a comparison of efficiency of absorption of anti-bone marrow cell activity by cells of the different lymphoid organs and cytotoxicity assays of the absorbed antiserum, it is concluded that approximately 15-25 per cent of the spleen lymphocytes and 20-40 per cent of the circulating lymphocytes in the rabbit are bone marrow-derived cells. The other lymphoid organs do not normally appear to possess these cells. [ABSTRACT FROM AUTHOR]

The effect of antigenic competition on antibody affinity was studied using a haptenic system in guinea-pigs. A moderate depression in the amount of antibody formed, as a result of antigenic competition, had relatively little effect on affinity. Increasing the dose of the competing antigen resulted in a greater degree of competition. Under these conditions a large amount of low affinity antibody was produced by the animals while essentially no high affinity antibody was detectable. Thus, marked competition appeared to result in a failure to select for high affinity antibody synthesis. [ABSTRACT FROM AUTHOR]

Parental thymocytes, inoculated into F1 mice which have been depleted of lymphoid cells by lethal irradiation, react to the host antigens which are contributed by the reciprocal parent in the F1 cross, by synthesizing DNA. The amount of DNA the parental thymocytes synthesize can be regulated by the addition of F1 thymocytes to the lethally irradiated F1 recipient F1 thymocytes suppress the response of a highly responding inoculum of parental thymocytes and boost the response of an inoculum responding less well. These regulatory effects of F1 thymocytes are not abolished by 900 R of irradiation 900 R-irradiated parental cells which are themselves incapable of DNA synthesis can also affect the response of DNA synthesizing cells. As with F1 thymocytes, the effect that 900 R-irradiated parental thymocytes has depends on the activity of the DNA synthesizing population; when it is high the effect is suppressive, when it is low there is augmentation. These results indicate that during the course of their response to antigen, T cells may transmit signals to other T cells which in turn transmit feedback signals to the primarily responding cells and in so doing alter their response. Such circular interactions between T cells may play an important role in immunological homeostasis [ABSTRACT FROM AUTHOR]

HgA-positive red cells were treated in vitro with approximately 10 μmoles N-ethylmaleimide (NEM) per ml cells for 1 hour at 37° and then injected into the circulation of HgA-negative rabbits; all the cells were cleared within 24 hours After 1-3 months the animals were given a series of injections of untreated HgA-positive red cells at 3-monthly intervals. Five out of seventeen rabbits showed progressively diminishing survival of HgA-positive red cells with the development of anti-HgA. On the other hand, in eight rabbits red cell survival following three consecutive injections of untreated red cells was normal or almost normal and in four further rabbits survival was initially subnormal but became progressively longer and was almost normal following a third injection of cells. Thus, in as many as twelve out of seventeen animals (70 per cent) the survival of HgA-positive red cells following a third injection of untreated cells was normal or almost normal whereas this pattern was previously observed in only seven out of fifty-one animals (14 per cent) not given an initial injection of NEM-treated cells. It is concluded that the injection of NEM-treated HgA-positive red cells to HgA-negative rabbits induces a degree of immunological tolerance to the HgA antigen. [ABSTRACT FROM AUTHOR]

Antibody to galactocerebroside can be produced in rabbits by the injection of the hapten together with a carrier protein (GC.BSA) or by immunization with the myelin fraction of brain homogenates (GC.M). The anti-galactocerebroside activity of both sera is mainly directed towards the galactose moiety of the galactolipid. In a complement fixation system they react with galactocerabroside (galactosylceramide) and monogalactosyldiglyceride, but not with glucocerebroside (glucosylceramide). Passive cutaneous anaphylaxis can be elicited by the carrier, but not the hapten. There is no demonstrable reaction to the glycolipid itself-even when tested in association with auxiliary lipids or the carrier protein; or as a component of solubilized myelin. The specificity of antibody to galactocerebroside appears to be unaffected by the nature of the carrier or associated proteins. This is shown by the fact that antisera to GC.BSA and GC.M react in an identical fashion with the lipid-protein complexes formed when myelin is solubilized with lysolecithin. Complement fixation is increased by solubilization, but increasing the lysolecithin/myelin ratio above the minimum necessary to render myelin completely soluble decreased the specific activity. Following isopycnic centrifugation maximum complement fixing activity was present in a fraction having a density of 1.04 at 10°, corresponding to one of three peaks of galactocerebroside concentration. However, precipitin reactions were obtained over a range of fractions of higher density. These results suggest that galactocerebroside is present in myelin in at least two forms and provides further confirmation of the fact that this hapten is responsible for a large part of the organ-specific complement fixing and precipitating activity of anti-myelin serum. [ABSTRACT FROM AUTHOR]

The progeny of mothers subjected to marginal lipotrope or moderately low protein diets exhibit deficient humoral immune responses. Serum antibody titres and numbers of antibody-forming cells to sheep erythrocytes (SRBC) are lower in the offspring of mothers whose diets were limited in either percentage protein or percentage lipotropes than in offspring whose mothers were fed a complete diet. Immune lymphocyte stimulation by SRBC antigens was marginal and not measurably different between the progeny of malnourished mothers and controls. The in vitro response of' spleen cells from offspring of nutritionally deprived mothers to the T-cell mitogen phytohaemagglutinin (PHA) is considerably less than that of controls. Thymus cells from marginal lipotrope offspring respond well to PHA, suggesting that PHA-reactive cell migration may be inhibited in these animals. These results, obtained using a T-dependent antigen (SRBC) and a T-dependent mitogen (PHA), support the conclusion that maternal dietary deficiency can adversely affect T-cell function in rat offspring. [ABSTRACT FROM AUTHOR]

Injection of bovine serum albumin (BSA) with the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) as adjuvant strongly primes mice for booster injections of BSA alone. The best doses of antigen for booster injections varied according to the frequency of antigen injections and the time interval between antigen injections. Increase in memory following the injection of BSA mixed with CPS-K adjuvant was first detected 10 days later. Memory continued to increase as the time interval after priming was increased to 90 days. Memory for the tertiary response increased after the optimum secondary antigenic stimulus. Increase in memory after the secondary antigenic stimulus was detected as early as 7 days after injection. Even secondary injection of the high dose of 50 mg of BSA did not exhaust immunological memory. Memory was also increased after the tertiary antigenic stimulus. Extremely high antibody responses (up to 492 mg protein per ml of antibody) could be obtained by eliciting tertiary and quaternary antibody responses optimally at the time memory was developed to the maximum level. [ABSTRACT FROM AUTHOR]

The immunochemical interaction between a macromolecular antigen and its corresponding immunoglobulin G is traditionally described in terms of a precipitation phenomenon. In heavy antigen excess the dominating reactions will follow the upper part of the reaction scheme, whereas a low antigen excess will lead to antibody-rich complexes as shown in the bottom of the scheme. Some of the latter complexes may be scarcely soluble and may have an inherent tendency to cohere; so that the process of precipitation may involve formation of covalent immune specific bondings as well as non-covalent bondings.

Studies on the diverse nature of the immune response of animals to different antigenic determinants on CEA indicate that the type of antiserum used is of prime importance in determining differences or identities between antigens isolated from tumour and normal tissues. One type of antiserum against CEA shows cross-reactions with a normal colon antigen (NCA) found in both malignant and normal tissues. This finding confirmed that a common determinant is shared by both CEA and NCA. A second type of anti-CEA did not cross react with NCA but reacted only with CEA, providing evidence for a unique CEA determinant. Yet a third and most common type of antiserum to CEA reacted equally well with CEA and NCA and was unable to distinguish between the two. This third type of anti-CEA was completely absorbed with NCA. Failure to recognize this type of anti-CEA would lead to erroneous conclusions regarding the existence of a unique antigenic determinant on CEA. [ABSTRACT FROM AUTHOR]

We have confirmed that adherence of antibodies to spleen lymphocytes is stabilized when the antibodies form complexes with antigen. Furthermore, there is evidence that antibodies having both binding sites occupied are less easily supplanted from the lymphocyte receptor by unspecific IgG than antibodies carrying one antigen only. Based on these results a hypothetical model for a feed-back control of the humoral immune response is put forward. [ABSTRACT FROM AUTHOR]

In adult chickens administration of 4 mg of bovine serum albumin as a multiple emulsion (water-in-oil-in-water) by the s.c., i.m. or i.p. route stimulated a persistent precipitin response that was still detectable in nine out of twelve birds when the experiment was terminated 286 days after injection. In each group the mean serum total antibody response curve was biphasic. An initial rapid response, reaching a peak of 350-500 micro gram antibody N/ml of serum on day 7-9, declined in fluctuating fashion and was succeeded after 30-60 days by a slower sustained rise in antibody level, reaching a peak similar to that of the initial response. Splenectomy impaired precipitin production, delayed and suppressed the initial phase of antibody synthesis, but did not significantly alter the second phase. Synthesis during the secondary phase is considered to proceed in the granulomata where, in contrast to other tissues of the body, antigen remains in readily detectable amounts for several weeks after injection. [ABSTRACT FROM AUTHOR]

Using the previously described animal model in which the effect of hepatic uptake of SRBC injected into the rat portal venous system was studied, the effect of two hepatotoxins carbon tetrachloride and D-galactosamine--is described. Carbon tetrachloride results in an enhanced primary immune response to SRBC injection and the abolition of the difference in immune response to repeated injections via the portal vein and inferior vena cava. Radioactive labelling of SRBC shows that the enhanced primary response is accompanied by a significant reduction of hepatic uptake. No significant increase in splenic uptake was noted. In contrast, the production of galactosamine hepatitis did not affect the immune response to SRBC. These findings are considered in the light of the pathogenesis of the hyperglobulinaemia which is associated with liver disease. [ABSTRACT FROM AUTHOR]

An experimental animal model is described in which small injections of antigen (SRBC) into the portal venous system of the rat produces a reduced immune response in comparison with that obtained following similar injection into the inferior vena cava. The difference in humoral response, measured by circulating haemagglutinins and haemolysins was only detectable after repeated doses of antigen. The dose of SRBC necessary to demonstrate this difference is shown to be critical. Cell-mediated immunity-determined by measuring ear swelling 24 hours after intra-auricular injection of antigen-could be demonstrated in animals immunized via the inferior vena cava but not in those immunized via the portal vein. Labelling of the antigen with radioactive chromium (5Cr) showed that the increased immune response to inferior vena cava injected antigen was accompanied by a reduced hepatic uptake of antigen, but no significant alteration in splenic uptake. [ABSTRACT FROM AUTHOR]

Studies on the immune response against hapten-autologous protein carriers in mice, guinea-pigs and rabbits have shown that the new antigenic determinants introduced in the carrier molecule by the hapten coupling reaction play an important role in the induction of both immunity and tolerance to these conjugates. The present experiments were designed to elucidate the specificity of the new antigenic determinants induced (1) by different haptens through the same coupling procedure and (2) by the same hapten coupled by different procedures. The results showed that both the nature of the hapten and the coupling procedure played a role in the serological specificity of the new antigenic determinants. [ABSTRACT FROM AUTHOR]

The experiments described in this paper extend the observations of previous work in vitro demonstrating a decrease in the frequency of antigenreactive units specific for horse RBC in spleen cells from mice primed with KLH. It was observed that the addition of lymphoid cells having T-cell function reconstituted the anti-HRBC response to normal values. Significant enhancement of the response beyond the normal values could be evoked using two dissimilar methods, (i) addition of allogeneic thymus cells, and (ii) restimulation in vitro with the priming antigen. The latter type enhancement was elicited by the addition of small doses of KLH to cultures of spleen cells from mice recently primed with KLH, including cultures otherwise demonstrating antigen-induced suppression. The stimulus required to enhance the response to HRBC in these cultures was specific for the priming antigen, KLH. These results are discussed in the light of current theories of 'antigenic competition' and specific heterologous enhancement. [ABSTRACT FROM AUTHOR]

Cell-mediated immunity was assessed in man by summation of positive delayed hypersensitivity (DHS) responses to five test antigens, Candida, mumps, trichophyton, tuberculin and streptokinase-streptodornase (Varidase). The study included forty-four controls comprising healthy persons and hospital inpatients with minor illnesses, forty-five aged persons, twenty-four patients with active chronic hepatitis (ACH), nine with systemic lupus erythematosus (SLE) and fourteen patients with rheumatoid arthritis. For controls and the group with ACH, cell-mediated immunity was assessed also by transformation of blood lymphocytes with phytohaemagglutinin (PHA). The incidence of positive DHS responses to all antigens fell with advancing age, and responsiveness was significantly lower in all three groups of immunopathic disease, particularly ACH. Prednisolone was not associated with significantly depressed DHS reactions, but combined prednisolone and azathioprine were. Weak DHS responses were associated significantly with low titres of natural antibody to flagellin and with lower humoral immune responses to flagellin. Lymphocyte transformation in response to PHA in ACH was significantly less than in healthy controls. Thus certain autoimmune diseases show an immunological imbalance in the form of depressed cell-mediated immunity to extrinsic antigens and 'hyperactive' humoral immune responses to 'self' antigens and selected extrinsic antigens. [ABSTRACT FROM AUTHOR]

The cellular response to HL-A antigens has been studied in thirty-one patients who had received a renal allograft from either a cadaveric or living donor, utilizing the leucocyte migration technique. The results indicate that inhibition of migration develops prior to or during the onset of a clinical rejection episode. This inhibition of migration reverts to non-inhibition in autologous serum when the rejection crisis is reversed. Inhibition of migration is still noted in allogeneic serum following this clinical reversal, but after varying time intervals the inhibition reaction also decreases in this serum. The abrogation of inhibition in autologous serum is specific to the HL-A antigens of the donor. These observations suggest that survival of human renal allografts depends on a blocking substance in the serum initially; subsequently, the loss of inhibition of migration with HL-A antigens in both autologous and allogeneic serum suggests an inactivation of specific antigen sensitive cells to the histocompatibility antigens of the donor. [ABSTRACT FROM AUTHOR]

In Sjögren's syndrome (SS), the earliest glandular infiltration by lymphoid cells surrounds the salivary ducts, which are also the target of the organ-specific antisalivary duct (ASD) autoantibody found in some patients with this disorder. A sensitizing antigen localized in ductal epithelial cells may elicit both humoral and cellular immune responses. In a study using coded specimens from twenty-five patients with SS and eight with rheumatoid arthritis, sera were tested for ASD, and lip biopsies were graded for the degree of lymphoid infiltration and destruction of labial salivary glands. Significantly less cellular infiltration was found in SS patients who had ASD compared to those who lacked this antibody. In SS, the group of ASD-negative patients had greater gland destruction and more severe xerostomia. The possible role of ASD as a blocking antibody is suggested. [ABSTRACT FROM AUTHOR]

Guinea-pigs were immunized with an emulsion of human thyroglobulin (Tg) and BCG vaccine in Freund's incomplete adjuvant. Peripheral blood lymphocytes binding Tg and purified protein derivative of mammalian tuberculin (PPD) labelled with 125I were demonstrated with an autoradiographic technique. The percentage of these cells was compared with the size of the delayed hypersensitivity (DH) skin reactions to Tg and PPD, and Tg antibody titres at intervals up to 35 days after immunization. The individual responses to Tg showed the time course of primary immune reactions although they did not parallel each other closely. By contrast, a depression of cutaneous DH to PPD was observed in spite of the presence of substantial numbers of 125I-PPD-binding peripheral blood lymphocytes. In non-immune guinea-pigs, approximately 2-8% of peripheral blood lymphocytes bound 125I-PPD whereas <0-l% bound 125I-Tg. The significance of antigen-binding lymphocytes in the immune response is discussed, and it is suggested that the presence of a substantial pool of antigenbinding lymphocytes in unprimed animals may be of importance in the induction of DH. [ABSTRACT FROM AUTHOR]

Anti-erythrocyte autoantibodies of two distinct antigenic specificities can be recovered from immunoglobulin-coated NZB erythrocytes. These autoantibodies react with either exposed (X) or hidden (HB) antigenic determinants on murine red cells and both types can be neutralized by mouse plasma. Antibody neutralization by plasma is dependent on two distinct plasma activities which appear to be soluble analogues of the erythrocyte surface autoantigens X and HB. The soluble erythrocyte antigens SEA-X and SEA-HB can be separated by molecular exclusion chromatography, with approximate sizes of 2 × 105 for SEA-X and &ges; 5 × 106 for SEA-HB. The presence of these soluble erythrocyte autoantigens in the plasmas of 'autoimmune' NZB mice has to be considered in relation to the immunologic homeostasis of these autoantibody responses and pathogenesis of both the autoimmune haemolytic anaemia and the autologous immune complex disease of these mice. Individual anti-erythrocyte autoantibodies of both anti-X and anti-HB types exhibit discrete and individually distinctive differences in affinity for autoantigen and also in respect to antigenic determinant specificity. These results suggest that factors which control the genetic selection of these responses in an inbred strain do not prescribe a single specific B lymphoid cell clone; but rather it appears that a number of different autoimmunocompetent B lymphocyte clones with differing affinity and determinant specificity for given autoantigen molecules may be derepressed by other events in the recruitment of the autoantibody responses. [ABSTRACT FROM AUTHOR]

Antigenic stimulation of the rat spleen to initiate a secondary response to tetanus toxoid (tet. tox.) has been found to have two effects on the recirculating lymphocytes which are migrating through the splenic pulp. Firstly, specific antigen-sensitive cells were selected from a population of immune lymphocytes during migration through an isolated, perfused spleen which was stimulated with tet. tox. This was supported by the substantial, and mostly specific, depression in the ability of such migrated cells to mediate a secondary response to tet. tox. and by the large secondary response produced by transplanted fragments of the perfused spleen without further exposure to antigen. Secondly the i. v. injection of tet. tox. into rats which had been previously transfused with labelled immune lymphocytes or alternatively labelled non-immune lymphocytes was followed by a transient retention of both populations in the spleen at the expense of the lymph nodes. Any surplus retention of the immune population in the stimulated spleen was not detected which suggests with certain reservations that only a small minority of even the immune population were antigen-sensitive cells. [ABSTRACT FROM AUTHOR]

Presence of soluble immune complexes was investigated in sera from persons with a well documented clinical diagnosis of leprosy. The complexes were detected by their reactivity with the Clq component of complement. More than 70% of the studied patients with lepromatous-leprosy had immune complexes demonstrable by this method (39/51), while only a small proportion of the healthy control group (1/35 or about 3%) had precipitable complexes. Two out of nine sera from patients with tuberculoid leprosy reacted when tested with Clq component. The presence of free-antibody to mycobacterial antigens was determined as well. The possible relationship between the presence of such immune complexes and the pathology of some reactional states of the disease is discussed. [ABSTRACT FROM AUTHOR]

The macrophage migration inhibition test was employed to show reactivity of maternal peripheral blood leucocytes to placental antigens. Four to 5 days after delivery, all of forty-one postpartum women tested had leucocytes in their blood that reacted with pooled antigens from five placentas. When antigens from a single placenta were used leucocytes from only the woman who donated that placenta and one of nine unrelated postpartum women were reactive. Leucocytes from seventeen-control subjects, including nulligravidous women, were non-reactive with either the single or the pooled placental antigens. The results indicated that the mothers may be specifically sensitized, as far as the cell mediated immune response is concerned, by the placenta during pregnancy. [ABSTRACT FROM AUTHOR]

Mice were immunized with an. allogeneic tumour antigen using various adjuvants and were subsequently challenged with live tumour cells. Immunization using certain adjuvants led to accelerated destruction of the subsequent tumour alto- graft, whilst the use of Freund's complete and incomplete adjuvant (CFA and IFA) led to enhanced tumour growth and eventual death of the mice. Pretreatment with Freund's complete adjuvant without antigen also resulted in enhanced tumour growth. Enhancing antibody was not detected in the sera or on the tumour cells, though some of the sera were able to inhibit cell-mediated cytotolysis of tumour cells. The mice pretreated with CFA, with or without antigen, showed a depressed cell-mediated cytotoxicity against tumour cells when compared with untreated mice. [ABSTRACT FROM AUTHOR]

Antibody activity against HSA and KLH was present in all five immunoglobulin classes of BALB/c mice. Bordetella pertussis vaccine was more effective in stimulating antibody production against HSA than against KLH and IgG1 and IgG2b antibody were affected more than the antibody present in the other immunoglobulin classes. The results are discussed in relation to the differing thymic dependence of these two antigens. [ABSTRACT FROM AUTHOR]

The mitogenic selectivity of four phytomitogens, phytohaemagglutinin (PHA), concanavalin (ConA), lentil mitogen (LM) and pokeweed mitogen .(PWM), and a series of heterologous antilymphocyte sera (ALS) for mouse T and B lymphocytes has been investigated using thymidine uptake as a measure of proliferative activity. The results show that PHA, ConA and LM stimulate T but not B cells whereas PWM activates both T and B cells. Of six mitogenically active ALS, five were T cell specific and one B cell specific. Cortisone resistant (T) cells within the thymus showed a much greater response to all mitogens than unselected thymocytes. However, ConA and LM activated a considerable response in the latter population. Selective activation of T and B cells by aspecific means may be useful both as a clinical tool and as an approach to gaining an understanding of antigen induction of immune responses. [ABSTRACT FROM AUTHOR]

The human secondary immune response to the protein antigen Keyhole limpet haemocyanin (KLH) was studied in thirteen normal adults. For secondary immunization and for measurement of delayed hypersensitivity, 100 μg of KLH was given intradermally to each individual between 81 and 375 days after primary immunization. Immunity was assessed by delayed hypersensitivity skin testing and measurement of antibody formation and KLH stimulated in vitro lymphocyte blastogenesis. Twelve of the thirteen subjects had positive KLH delayed hypersensitivity reactions. Prior to secondary immunization all thirteen had circulating lymphocytes responsive in vitro to KLH and all had circulating haemagglutinating antibody. After secondary immunization there was no further increase in the mean KLH-stimulated blastogenesis while the KLH haemagglutinin titre rose due to increased 7S antibody formation. Primary immunization with small doses of KLH was as effective in inducing immunological memory and a subsequent secondary response as immunization with large doses of the antigen. [ABSTRACT FROM AUTHOR]

The proliferative response of human blood lymphocytes to homologous cells in vitro (i.e. the mixed lymphocyte reaction) has been used as a model of cell-mediated immune responses to investigate the nature of the antigen receptor site involved in the initiation of these reactions. Pretreatment of lymphocytes with the Fabγ monomer of rabbit antisera to human immunoglobulin light chain determinants effectively suppressed subsequent responsiveness to antigen without impairing lymphocyte viability or response to phytohaemagglutinin. Experiments in which the dose of antigen and the time of addition of antigen relative to antiserum were varied suggested that anti-light chain antibodies compete with antigen for the receptor site. These results are discussed in relation to the problem of the chemical nature of the receptor site for transplantation reactions and delayed hypersensitivity. [ABSTRACT FROM AUTHOR]

Using a local passive transfer system in mice it has been possible to detect interaction between sensitized lymph node cells and antigen inducing contact sensitivity. Cells were injected into the ears of mice intracutaneously and antigen applied to the skin. A late inflammatory" response at the site was detected by measuring the 24-hour uptake of 51Cr-labelled indicator ‘inflammatory cells’ (peritoneal exudate or oxazolone-sensitized lymph node cells). Three days after local transfer the uptake in ears receiving sensitized cells and challenged with antigen was three-to ten-fold greater than in the ears of animals receiving cells or antigen alone. This phenomenon was dependent upon challenge with the appropriate antigen. Interaction was also detected when cells were transferred into one ear and antigen applied to the other. Experiments to explain this effect showed that transferred cells disappeared rapidly from the site of transfer. Antigen applied elsewhere enhanced their mobility and increased their arrival at the antigen site. [ABSTRACT FROM AUTHOR]

Blood group HgA negative rabbits were injected with 2 x 109 HgA positive erythrocytes from a donor rabbit. Assortative matings were set up between those rabbits which produced detectable anti-HgA (responders) and those which did not (non-responders). The progeny were injected with 2 x 109 HgA positive erythrocytes 3 months after birth and their anti-HgA response measured. It was found that 20/24 (83 per cent) of the offspring of responder parents, but only 4/26 (15 per cent) of the offspring of non-responder parents, produced detectable anti-HgA. No difference was found between the ability of responders and non- responders to produce haemagglutinins to various doses of sheep erythrocytes. In contrast, non-responder rabbits rarely responded to non-HgA blood group isoantigens on the donor erythrocytes whereas rabbits which responded to HgA after injection of the donor erythrocytes often responded to non-HgA isoantigens. Typing the cells of non-responder rabbits with the sera from responder rabbits containing non-HgA antibodies showed that the non-responder cells were antigenically more like the donor cells than were the cells from responder rabbits. The ability to respond to HgA was not associated with any particular heavy or light chain immunoglobulin allotype specificities. It is considered that HgA has an important helper function in regard to the antibody response to non-HgA antigens but the latter probably also have a similar but less marked effect in relation to the HgA antibody response. The genetic control observed is thought to operate through T cell recognition and reaction with HgA and other blood group determinants. [ABSTRACT FROM AUTHOR]

The effect of a single batch of horse anti-mouse thymocyte globulin on the immune response to type III polysaccharide antigen bas been investigated in 2–3-month-old male A/HeJ, C57BI, BALB/c, DBA/I, CBA and C3H mice. In almost all cases the intraperitoneal administration of 5 mg of this material on days -4 and -2 significantly suppressed the immune response to 0·1, 1·0 and 5·0 μg of antigen injected i.v. on day 0. Further studies undertaken in BALB/c mice indicated that effective suppression of the immune response to type III polysaccharide antigen could also be achieved by injecting 5 mg of this product (i.p.) some 15–30 minutes prior to antigenic challenge. Preliminary cell re constitution studies in antilymphocytic antibody-treated CBA mice indicate that the ability to respond to type III polysaccharide can be partially restored by the injection of syngeneic thymocytes, bone marrow cells or spleen cells. [ABSTRACT FROM AUTHOR]

The immunological significance of lipopolysaccharide (LPS) transfer from macrophage into lymphocytes was studied in an in vitro system in which the lymphocytes were incubated during 24-72 hours with macrophages which had previously ingested S. enteriditis LPS (during 1 hour). Our results show that the in vitro immune response to LPS requires co-operation of lymphocytes with macrophages. After 24-72 hours of contact of the lymphocytes with macrophages containing ingested antigen, we observed within lymphocyte population a time dependent increase of the number of LPS-binding cells. This result was obtained by means of two different methods: rosettes formation and autoradiography. Autoradiographies performed on thick and thin sections showed that after contact with macrophages which had ingested 14C-LPS, most rosettes forming cells (RFC) exhibited radioactivity. All these findings strongly argue in favour of the idea that LPS transfer from macrophages to lymphocytes is highly relevant for specific antibody synthesis by lymphocytes. [ABSTRACT FROM AUTHOR]

Intact IgG antibody can terminate established immune responses, whereas F(ab')2 antibody cannot do so. The difference between the two antibodies appears to be qualitative. F(ab')2 antibody, but not pepsin-digested normal serum, can interfere with the suppression and termination of immune responses induced by intact IgG antibody. These results are discussed in terms of the tripartite inactivation model. [ABSTRACT FROM AUTHOR]

The effect of a single batch of horse anti-mouse thymocyte globulin on the humoral immune response has been extensively investigated in 10-12-weekold male mice of six inbred strains. The preparation under test readily suppressed the primary immune response of A/HeJ, C57B1, DBA/1, CBA and C3H mice to 0.1, 1.0 and 10.0 mg doses of alum precipitated bovine serum albumin (alum BSA). However, at the doses used it generally failed to significantly suppress the primary immune response of BALB/c mice to 0.1 and 1.0 mg doses of this antigen. Furthermore, the effectiveness of the suppression was somewhat diminished by the incorporation of bordetella pertussis organisms into the alum BSA inoculum. The product also suppressed the secondary immune response to alum BSA in C3H mice and C57B1 mice but, at the same doses, was without significant effect on the secondary responses of A/HeJ and CBA mice. [ABSTRACT FROM AUTHOR]

Thermal regulation of the immune response was studied in toads following single injections of bacteriophage f2. The immune response was markedly inhibited in animals kept at 15° as compared to the controls (25°). The appearance of serum antibodies was delayed in animals kept at 15° for the first post-immunization week but their peak antibody levels were similar to those in toads maintained at 25° throughout. Transfer of animals from 25° to 15° 2 weeks after immunization only temporarily depressed the serum antibody levels but caused a marked delay in conversion from heavy to light antibodies. Our results are in keeping with the hypothesis that lowered environmental temperatures inhibit a variety of metabolic processes which may be concerned with the utilization of antigen and/or the synthesis of antibodies. [ABSTRACT FROM AUTHOR]

A system is described with which an antibody response to soluble chicken ovalbumin can be obtained in dissociated spleen cell cultures from primed mice. This was assayed by determining specific anti-ovalbumin plaque-forming cells (PFC). Only IgG-producing cells (indirect PFC) were seen. The mice received alum-precipitated ovalbumin i.p. and cultures were set up either late in the primary splenic response (23–27 days after injection) or near the peak of the response (10–14 days). With both groups secondary responses were seen in the presence of antigen on the fourth day of culture. In the second group PFC were present in the cultures at a high level initially. The number of PFC de- creased over the first 2 days, the rate of decrease being greater in the presence of antigen. When mice were primed with alum-precipitated ovalbumin together with B. pertussis as adjuvant, responses could not now be obtained in culture. With mice taken late in the primary response (23–27 days), a considerable number of PFC were present in the cultures initially. The number decreased throughout the 4-day period and the decline was accelerated by antigen. With mice taken near the peak of the response (10–14 days) no PFC were seen in culture, even on the first day, in the presence or absence of antigen. The first phenomenon, suppression by antigen, is considered to be of general significance since it may also be seen in cultures from mice receiving no B. pertussis as described. It is suggested that the second phenomenon is due to adverse culture conditions resulting from the white cell mobilization initiated by B. pertussis; after 23–27 days conditions have recovered to a point where suppression but not the secondary response can occur. The suppressive effect of antigen could be related to antigenic competition or tolerance. [ABSTRACT FROM AUTHOR]

Human serum albumin (HSA) and ferritin in Freund's incomplete adjuvant (FIA) were injected simultaneously, intraperitoneally into mice in various dose/ratios. The degree of suppression of the primary and secondary immune responses to a small dose of HSA was dependent on the dose of ferritin injected simultaneously. A totally suppressed primary response was associated with a secondary response which only attained the lextel of a primary response to HSA in FIA. Similar results were obtained in experiments in which a constant dose of ferritin and varying amounts of HSA were injected simultaneously in FIA into mice. Suppression of the immune response to alum-precipitated HSA in the presence of soluble ferritin was not as striking as when the antigens were injected with FIA. Nevertheless, suppression of the primary response was again associated with a reduced secondary response. The results are discussed in the context of the possible mechanism(s) of antigenic competition. [ABSTRACT FROM AUTHOR]

The immunological response to native levan (a fructose homopolymer with molecular weight 2 × 107) has been studied in (DBA/1 × CBA-T6T6)F1 mice by passive hemagglutination and plaque-forming cell (PFC) assays. It resembles type-specific pneumococcal polysaccharide (SSS) in eliciting a prolonged humoral antibody response over a wide dose range (0.0001-100 µg) and in inducing longlasting 'high zone' tolerance with a single injection (1 mg or more). Other similarities include an exclusively IgM response, independence of synergy with thymusderived lymphocytes and absence of immunological memory. On the other hand, parallelism between serum hemagglutinin and PFC levels following all doses of antigen implies that higher immunizing doses of levan, unlike SSS, do not engage in peripheral neutralization of antibody. It was concluded from studying the fate of 14C-labelled levan that this was attributable to more rapid elimination from the circulation and subsequent slow metabolism of this polysaccharide. Levan also differs from SSS in inducing tolerance directly, without a detectable prior immune phase. [ABSTRACT FROM AUTHOR]

The induction and loss of tolerance to native and depolymerized fractions of levan, a thymus-independent antigen, have been studied in (DBA/1 × CBA-T6T6)F1 mice by a direct plaque-forming cell (PFC) assay. Tolerance following 1 mg native levan began to break by 80 days, whereas mice remained specifically unresponsive 150 days after 10 mg. Effects attributable to long persistence of antigen have been demonstrated. The following main features of levan tolerance were established by transfer of spleen cells to 900 R-irradiated recipients: (1) the induction period is very short—less than 24 hours. (2) No detectable immunity accompanies or precedes induction. (3) The fall in immunogenicity with reduction in molecular weight (mol. wt) of levan is not accompanied by loss of tolerogenicity. An effectively tolerogenic, non-immunogenic fraction (mol. wt< 10,000) was found. (4) There is no rapid loss of tolerance following cell transfer (reactivity is only regained after 50 days), arguing against the existence of tolerant cells in this model. As these results and those from corresponding investigations with SIII and HGG all show major dissimilarities, it is considered imprudent to base generalizations concerning the nature of B cell tolerance on studies with only one type of antigen. Whether or not two different kinds of specific unresponsiveness might be implicated with these cells is discussed. [ABSTRACT FROM AUTHOR]

Soluble crystalline bacterial α-amylase (BαA)-mouse anti-BαA antibody complexes (Ag-Ab complexes) elicited a primary antibody response in mice with a single intravenous injection, while free BαA could not. The response was dose dependent. Ag-Ab complexes were not only phagocytosed but also degraded more rapidly than free BαA in vivo and in vitro but these characteristics themselves were not important for immunogencity of the complexes. The Ag-Ab complexes phagocytosed by cells in normal spleen and lymph node elicited a primary antibody response when injected into non-irradiated mice but the response was suppressed when anti-BαA antibody was simultaneously injected. On the other hand, free BαA phagocytosed by cells could not elicit the response. The degraded products of complexes phagocytosed by normal spleen and lymph node cells were highly immunogenic and probably retain antigenic fragments. They elicited an even higher primary antibody response than the original complexes and were also more effective in eliciting a secondary response from primed cells than the original complexes or free BαA. The degraded products of flee BαA, however, were ineffective not only for the primary response but also for primed cells. Ag-Ab complexes prepared with heterologous rabbit antibody were ineffective for the primary antibody response. [ABSTRACT FROM AUTHOR]

Bone marrow cells and thymus cells were observed in cell transfer expehments to collaborate in the production of anti-BSA antibodies. The target cells for tolerance induction either with a 'low dose' of antigen (100 µg of deaggregated BSA once a week × 5) or with a 'high dose' (a single injection of 5000 µg) were identified by the same technique. In 'low dose' tolerance, some indication was obtained that thymus-derived cells in peripheral lymphoid systems were the target cells; bone marrow-derived cells appeared not to be so susceptible, and the cells residing in thymus or bone marrow seemed to remain unimpaired, in contrast, the injection of a 'high dose' of tolerogen rendered both types of cells in spleen, thymus cells and bone marrow cells, unresponsive or hyporesponsive in parallel with one another. [ABSTRACT FROM AUTHOR]

The increased intensity and prolongation of contact hypersensitivity reactions in animals treated 3 days prior to sensitization with 300 mg/kg cyclophosphamide (CY) has been investigated. No evidence has been found of increased activity of lymphoid tissue or non-specific skin reactivity following CY treatment. However there was evidence of normal T-lymphocyte function associated with reduced B-lymphocyte function. Partial reconstitution could be obtained by transplanting spleen and the effect of CY treatment could be partially reproduced by splenectomy following sensitization. It is suggested that a B-lymphocyte response m soluble antigen modulates a normal cell-mediated immune response during the development of chemical contact sensitivity in the healthy animal and that this could be blocked completely by treatment with CY prior to sensitization or partially by splenectomy after sensitization. [ABSTRACT FROM AUTHOR]

Complexes of Haemophilus influenzae cells with and without intact capsular material were prepared with type specific antisera. Thin sections of positively stained specimens were prepared and examined in the electron microscope. In the absence of capsular material the antibodies were observed bound close to one another in the immediate area of the bacterial cell wall. When capsular antigen was present the antibodies were farther separated from one another in the complex and appeared to be attached at random sites along the capsular polymers with occasional individual particles being observed. This positive staining approach appears to be a useful method to observe the molecular structure of precipitated immune complexes. [ABSTRACT FROM AUTHOR]