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A list of forthcoming papers related to immunology is presented. These include "Variable influences of iodine on the T-cell recognition of a single thyroglobulin epitope," by Hong Jiang, "Triacylated lipoproteins derived from Mycoplasma pneumoniae activate NF-jB through TLR1 and TLR2," by Takashi Shimizu, and "Disruption of Rxra gene in thymocytes and T lymphocytes modestly alters lymphocyte frequencies, proliferation, survival and Th1/Th2 balance," by Alexander Borowsky and Kevin Kent Lloyd.

In the early 1970s a spate of papers by research groups around the world provided evidence for a negative regulatory role of thymus-derived lymphocytes (T cells). In 1971, Gershon and Kondo published a seminal paper in Immunology entitled ‘Infectious Immunological Tolerance’ 1 indicating that such negative regulation could be a dominant effect that prevented otherwise ‘helpful’ T cells from mediating their function. Over the next decade, suppressor T cells, as these negative regulatory cells became known, were intensively investigated and a complex set of interacting cells and soluble factors were described as mediators in this process of immune regulation. In the early 1980s, however, biochemical and molecular experiments raised questions about the interpretation of the earlier studies, and within a few years, the term ‘suppressor T cell’ had all but disappeared from prominence and research on this phenomenon was held in poor esteem. While this was happening, new studies appeared suggesting that a subset of T cells played a critical role in preventing autoimmunity. These T cells, eventually dubbed ‘regulatory T cells’, have become a major focus of modern cellular immunological investigation, with a predominance that perhaps eclipses even that seen in the earlier period of suppressor T cell ascendancy. This brief review summarizes the rise and fall of ‘suppressorology’ and the possibility that Tregs are a modern rediscovery of suppressor T cells made convincing by more robust models for their study and better reagents for their identification and analysis. [ABSTRACT FROM AUTHOR]

The experiments described in this paper have examined the migration of three fluorochrome-labelled T-lymphocyte subsets (CD4+, CD8+ and γδ+T19+) on a single passage from blood to lymph, through prescapular lymph nodes. Lymphocytes obtained from prescapular efferent lymph were labelled in vitro with fluorochrome and returned to the blood of the same animal. Over the next 2 days, lymph was continuously monitored and the cells in all collections, including the one used for intravenous infusion, were phenotyped and analysed by flow cytometry. Significant differences in the subset ratios between the infused, starting population and the recirculated population iodicated that CD4+ and γδ+T19+ lymphocytes are extracted by a resting lymph node at the same rate and that both are extracted at a faster rate than CD8+ lymphocytes. The results presented here also suggest that a unique subset of γδ+T19+ lymphocytes may be present in blood that does not recirculate through peripheral lymph nodes. [ABSTRACT FROM AUTHOR]

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

T cells involved in specific and nonspecific co-operation belong to a long-lived population. However, under conditions of limiting dilution of T cells it is not a common event to detect both types of co-operative event in a single microculture well. Likewise, as far as specific co-operation is concerned, the simultaneous expression of both direct and indirect PFC responses in a single microculture well is also unusual. Estimates obtained of the number of PFC generated by one T cell in specific co-operation correspond well to those generated by a single B cell; and it would seem that under conditions of the microculture system there is a marked restriction in the number of B cells that a single T cell may interact with in the short term. This restriction seems to be of a one T-cell to one B-cell relationship. [ABSTRACT FROM AUTHOR]

I have briefly reviewed the factors that motivated me to change my views about the existence and importance of suppressor/regulatory T cells and to devote the majority of my laboratory efforts to this newly revitalized area of immunologic research. I am optimistic that manipulation of regulatory T-cell function will shortly be applicable to the clinic. [ABSTRACT FROM AUTHOR]

The concept of T-cell mediated suppression evolved more than 30 years ago. At that time it spawned many claims that have not stood the test of time. The rediscovery of suppression phenomena and regulatory T cells over the past 15 years created schizophrenic responses amongst immunologists. Some claimed that the new proponents of suppression were, once again, bringing immunology into disrepute, whilst others have embraced the field with great enthusiasm and novel approaches to clarification. Without faithful repetition of the “old” experiments, it is difficult to establish what was right and what was wrong. Nevertheless, immunologists must now accept that a good number of the old claims were overstated, and reflected poor scientific discipline. [ABSTRACT FROM AUTHOR]

Hepcidin regulates intracellular iron levels by interacting with and promoting the degradation of ferroportin, a membrane protein and the only known cellular iron exporter. Studies of hepcidin expression and regulation have focused on its effects in innate immunity and as a regulator of systemic iron metabolism. In the present study we characterized the expression of hepcidin messenger RNA (mRNA) in human peripheral blood mononuclear cells (PBMCs) with a focus on peripheral blood lymphocytes (PBLs). We found that (1) all human PBMCs analyzed express basal hepcidin mRNA levels; (2) hepcidin mRNA expression increases after T-lymphocyte activation; (3) expression by PBLs increases in response to challenge by holotransferrin (Fe-TF) and by ferric citrate in vitro; (4) the Fe-TF-mediated up-regulation of hepcidin decreases ferroportin expression at the cytoplasmic membrane of PBLs; and (5) silencing of tumour necrosis factor-α (TNF-α) abrogates the effect of Fe-TF. In summary, we show that hepcidin expression determines intracellular iron levels by regulating the expression of ferroportin, as described in other cells, and that inappropriately low expression of hepcidin impairs normal lymphocyte proliferation. The results establish hepcidin as a new player in lymphocyte biology. [ABSTRACT FROM AUTHOR]

The rise-and-fall and reincarnation of suppressor T cells is reviewed from the perspective of a participant in the field. [ABSTRACT FROM AUTHOR]

Since it was previously shown that protein antigens applied epicutaneously in mice induce allergic dermatitis mediated by production of T helper 2 (Th2) cytokines we postulated that this might induce suppression of Th1 immunity. Here we show that epicutaneous immunization of normal mice with a different protein antigen applied on the skin in the form of a patch induces a state of subsequent antigen-non-specific unresponsiveness caused by suppressor T cells (Ts) that inhibit sensitization and elicitation of effector T-cell responses. Suppression is transferablein vivobyαβ-T-cell receptor CD4+ CD8+ double positive lymphocytes harvested from lymphoid organs of skin patched animals and are not major histocompatibility complex-restricted nor antigen specific. Both CD25+ and CD25– CD4+ CD8+ T cells are able to suppress adoptive transfer of Th1 effector cells mediating cutaneous contact sensitivity.In vivotreatment with monoclonal antibodies showed that the cytokines interleukin (IL)-4, IL-10 and transforming growth factor-β (TGF-β) are involved in the induction of the Ts cells. Additionally, using IL-10–/– mice we found that IL-10 is involved in skin induced tolerance. Furtherin vitroexperiments showed that lymph node cells of skin tolerized mice non-specifically suppress[3H]thymidine incorporation by antigen-stimulated immune cells and this effect can be abolished by adding anti-TGF-β, but not anti-IL-4 nor anti-IL-10 antibodies. These studies indicate the crucial role of TGF-β in skin induced tolerance due to non-antigen-specific Ts cells and also show that IL-4, IL-10 and TGF-β play an important role in the induction of epicutaneously induced Ts cell suppression. [ABSTRACT FROM AUTHOR]

The WC1 protein is a cell surface constituent of bovine γδ T cells and is absent from most or all CD4+, CD8+ T cells and from B cells. It is a single polypeptide chain of 1413 amino acids consisting of 11 non-identical repeats of a 110 amino acid consensus sequence, homologous to the macrophage scavenger receptor cysteine rich (SRCR) domain. A 1059 nucleotide segment of the bovine WC1 cDNA sequence was used as a probe to molecularly clone homologous DNA segments from a sheep genomic library in which the presence of numerous positive plaques was documented. The high representation of such recombinants (1-2/1000 clones) within the library suggested the existence of multiple genes for WC1 (called T19 in sheep) and supported Southern blotting data which revealed an unexpectedly high number of WC1/TI9 restriction fragments in sheep genomic DNA. Restriction digests of 27 samples of TI9 genomic recombinants were examined by electrophoresis and Southern blotting. All but two pairs of recombinants exhibited non-overlapping restriction digest patterns. Four recombinant DNA samples were partially sequenced and in all cases putative exons were identified and exhibited high homology to appropriate segments of the WC1 cDNA at the levels of both nucleotide and amino acid sequence. Furthermore, multiple nucleotide and amino acid differences occurred between all sequences compared, establishing the existence of a repertoire of non-identical T19 genes, each with the potential to encode a different protein. [ABSTRACT FROM AUTHOR]

A 180,000 MW molecule has been identified on porcine leucocytes that is the homologue of the 215,000/300,000 MW WC1 (T19) leucocyte antigen previously considered to be restricted to ruminants. In ruminants the WC1 molecule is expressed by a T-cell subpopulation that is CD2-CD4-CD8-CD5+ and that is γδ T-cell receptor positive (TcR+). In pigs, the 180,000 MW molecule, identified by a new monoclonal antibody CC101, is expressed by a γδ TcR+ T-cell subpopulation that is also CD2-CD4 CD8. The p180+ cells are a major T-cell subpopulation comprising approximately 40% of the peripheral blood mononuclear cells from 6-9-month-old pigs. Expression of p180 identifies the majority of the CD2-CD4-CD8- T cells in porcine blood. The p180+ T cells have a distribution in lymphoid tissues that is distinct from that oft cells that express the CD2, CD4 or CD8 molecules. They are evident particularly in the thymic medulla, the epithelium, lamina propria and interfollicular areas of the small intestine, and the superficial dermis of the skin, but largely absent from conventional T-dependent areas of secondary lymphoid tissue. [ABSTRACT FROM AUTHOR]

The effects of antigenic stimulation on the expansion of T-cell dependent areas in lymph nodes of mice were studied in relation to the effects on high endothelial venules (HEV) located in this area. Lymph nodes regional to areas of skin that had been treated with solutions of oxazolone were studied at several time-points after stimulation. The following measurements were made relative to lymph nodes of untreated animals: (i) the expansion of the T-cell dependent area in combination with the increase of HEV in this area, as detected by the HEV-specific mAb MECA-325, using morphometric analysis; (ii) the influx of FITC-labelled lymphocytes from the blood into the lymph node by FACS; (iii) the capacity of HEV to bind lymphocytes using an in vitro binding assay. Morphometry showed that T-cell dependent areas increased rapidly after stimulation with oxazolone and although the mean area of MECA-325-positive HEV had also increased, this increase lagged behind the expansion of the T-cell area. Therefore the amount of HEV per T-cell area in an antigen-stimulated lymph node was smaller than in an untreated lymph node and correlated with the percentage of FITC-labelled cells that had entered it. In a lymph node from an oxazolone-treated animal this percentage was decreased to the same order of magnitude as the area of HEV per T-cell area, but the overall binding capacity of HEV was not affected by oxazolone treatment. Antigenic stimulation therefore leads to a rapid expansion of the potential sites of lymphocyte entry into a lymph node, but the efficiency of the HEV does not change. [ABSTRACT FROM AUTHOR]

Serine protease genes (C11, B10 and HF) derived from activated cytolytic T lymphocytes have been shown to be important in CTL-mediated cytotoxicity. In this study, we examined the expression of these genes in fresh natural killer (NK) cells from severe combined immunodeficiency (SCID) and athymic nude mice, as well as in T-cell lines with NK activity. All of these serine protease genes were expressed in NK cells freshly isolated from SCID and athymic nude mice. In addition, all lines showed similar strong levels of expression of C11 and B10 genes, but not the HF gene. However, levels of expression in the T-cell lines did not correlate with levels of NK-like cytotoxicity. These results suggest that C11, B10 and HF serine protease genes are necessary but not sufficient for NK-like cytotoxicity. [ABSTRACT FROM AUTHOR]

X-irradiated (250 rads) A mice injected with syngeneic trinitrophenylated spleen cells (Syn-TNP-SC) developed syngeneic delayed-type hypersensitivity (Syn-DTH) after footpad challenge with syngeneic concanavalin A-induced lymphoblasts (Syn-Con A blasts), as indicated by footpad swelling and lymph-node proliferation assays. Genetic analysis with different recombinant strains of mouse revealed that the H-2Dd subregion restricts these immunological activities. A small immunogenic entity was isolated from Syn-TNP-SC extract by gel filtration and affinity chromatography with anti-Dd antibody. X-irradiated A mice injected with this antigen also generated inflammatory responses after challenge with Syn-Con A blasts. Analysis of the data obtained from the gel filtration and the affinity chromatography suggest that the Syn-DTH-stimulating antigen is a fragment of the H-Dd heavy chain with a molecular weight (MW) of 5,000 to 10,000. This fragment does not contain TNP molecules or sugar moieties and neither does it express affinity for antibodies against class 11 products. Ltk- cells transfected with the H-2Dd gene also induced Syn-DTH in X-irradiated A mice, while the parent cells failed to stimulate such a response. Taken together these findings indicate that the selection process in the thymus is not absolute and T cells recognizing self-major histocompatibility complex (MHC) products do migrate from this organ to the periphery of the immune system. The possible biological significance of these autoreactive cells is discussed. [ABSTRACT FROM AUTHOR]

Lymphocytes from natural killer (NK) cell-deficient beige mice have a poor ability to induce many different forms of graft-versus-host reaction (GvHR). In this study, we have examined whether this defect could reflect an associated abnormality in beige T-lymphocyte function. Compared with normal, congenic C57B1/6 (B6) mice, beige mice had similar numbers and proportions of T-cell subsets and generated normal allospecific delayed-type hypersensitivity (DTH) responses in vivo. In addition, beige mice developed normal or enhanced DTH responses to the protein antigen, ovalbumin (OVA), and were fully susceptible to the induction of tolerance by feeding OVA. Beige lymphocytes recirculated normally in vivo and showed enhanced proliferative responses to mitogens and alloantigens in vitro. In contrast, beige responder cells generated poor cytotoxic T-lymphocyte (CTL) responses in vitro and had quantitatively identical defects in CTL and NK cell activation after alloimmunization in vivo. These results suggest that although many effector and regulatory T-cell functions are normal in beige mice, the NK-cell defect in these animals is paralleled by impaired CTL activity. We suggest that abnormal T-cell function accounts for the inability of beige lymphocytes to induce GvHR. [ABSTRACT FROM AUTHOR]

Treatment of guinea-pig spleen cells with glucoeorticoids, such as dexamethasone (DEX), reduces concanavalin A (Con A)-induced production of chemotactic lymphokines (CLK), such as eosinophil chemotactic factor and macrophage chemotactic factor. The decreased CLK production is not caused by a direct effect of DEX on the spleen cells producing CLK. because Con A-induced CLK production is suppressed when the cells are cultured together with cell-free culture supernatants of the spleen cells which had been pretreated with DEX. A soluble suppressive factor, termed CLK-SF, with a MW of about 20,000, seems to be responsible for the suppression of both CLK production. CLK-SF is produced from DEX-treated T lymphocytes. CLK-SF probably exerts a critical role in the early stage of CLK production. In contrast, CLK-SF fails to inhibit Con A-induced lymphocyte proliferation, although DEX itself suppresses lymphocyte proliferation. This suggests that DEX suppresses Con A-induced CLK production by a different mechanism from that for lymphocyte proliferation. [ABSTRACT FROM AUTHOR]

Two PPD-reactive T-cell lines and two clones derived from them have been characterized. The lines were maintained for a period of 10–12 weeks in 11–2 containing medium. The clones were derived from the uncloned lines by the limiting dilution method and maintained in culture for 12 weeks. The cloning efficiency was 1%, Both the cloned and the uncloned lines were highly reactive to tuberculin in a proliferation assay and produced migration inhibition factors following antigenic stimulation. Both these functions were dependent on the addition of antigen-presenting cells and genetically regulated by Class II molecules of the MHC. Each uncloned line and the clones derived from them were restricted by just one of he DR alleles of the autologous host. An analysis of ell types involved in antigen presentation showed that macrophages and Epstein-Barr virus-transformed B-cell lines induced both proliferation and MIF secretion in the T-cell lines and clones cultured with PPD. Phenotypic studies indicate that the cells are Sheep E+, OKT4+, OKT8- and HLA-DR+. [ABSTRACT FROM AUTHOR]

Different T-cell subsets participating in immune responses were detected at a high frequency by a modified virus plaque assay (VPA). By using the modified VPA, different activated T-cell subsets generated in primary immune responses, helper and suppressor T cells participating in antibody formation, and effector T cells involved in the delayed-type hypersensitivity (DTH) reaction were enumerated directly without in vitro antigen stimulation. The frequency of detection in immune systems used was 7·5–17·7 V-PFC/103 spleen cells. Although neither helper T cells for antibody formation nor effector T cells for DTH reaction were detected as V-PFC at a high frequency by the original VPA, it was also found in secondary immune response that Lyt 1 positive, antigen-specific helper and effector T-cell subsets, and cyclophosphamide (CY)-resistant precursors were enumerated at a high frequency by the modified VPA when they received in vitro antigen stimulation, and that the proliferative stage of these cells was critical for the development of V-PFC. [ABSTRACT FROM AUTHOR]

Mast cell differentiation was generated in the following three experimental situations: (i) infection of mice with Schistosoma Mansoni or with Nippostrongylus brasiliensis and growth of the lymph node cells in the presence of the corresponding helminth antigen; (ii) immunization with horse serum and growth of blood and lymph node cells in the presence of the horse serum; (iii) exposure of T-cell depleted suspensions of lymph node cells from unimmunized mice to T-cell factor (TCF) released into medium of the young cultures of (i) and (ii). This differentiation was also obtained when lymph node cells from athymic nude mice were exposed to TCF. The cell suspensions were plated on X-irradiated fibroblast monolayers prepared from embryonic mouse skin. Screening of the suspensions before plating on the fibroblasts in culture revealed no young forms of mast cells, and none were present in culture of nude mice lymph node cells maintained without TCF. Primordial appearance of metachromatic granules generally in the golgi zone was first seen in many 'large lymphoid cells' as early as 18 hr after plating. This was followed by increase in the cytoplasm volume, increase in granule number and mitosis, ending at 10-18 days with homogeneous populations of mature mast cells. When the mesenteric lymph node cells from mice infected with the helminths were grown in the absence of fibroblasts but in the presence of the antigen, homogeneous populations of cells with extended cytoplasm, filled with unstained vacuoles developed during days 7-13. These cells did not contain histamine (or at most 0.2 µg per 106 vacuolated cells). When these cells were plated on fibroblast monolayers clear granule formation in all the vacuoles was seen 2 days later. It increased progressively in size and staining intensity, until the vacuoles transformed into typical mast cell granules. By the fourth day the vacuolated cells attained the typical mast cell morphology and the histamine content greatly increased (from 0.12 µg per 106 vacuolated cells to 3.02 µg per 106 mast cells). These mast cells were readily degranulated by monoclonal anti-DNP-BSA IgE, and the antigen, releasing 90% of the histamine. The study shows that mucosal mast cells formation from 'large lymphoid-like' cells present in the blood and in the lymph, is stimulated by TCF. The condensation of the metachromatic material and histamine synthesis depends on other cells, presumably fibroblasts which comprise the principal cell in the embryonic skin monolayers. The mechanism of the fibroblast influence is not yet known. [ABSTRACT FROM AUTHOR]

Small lymphocyte subsets were characterized radioautographically on the basis of several surface markers, viz. surface Ig (S-Ig), Thy-1 and Lyt (Ly-1, Ly-2 and 3) antigens in host lymphoid organs (thymus, spleen and blood) as well as at the turnout site at various stages of subcutaneous growth of two different syngeneic turnouts—MPC-11 plasmacytoma and WEH I- 164 fibrosarcoma in BA L B/c mice. In both tumour-host combinations there was a rise in the levels of null (S-Ig-, Thy-1-) small lymphocytes as well as the Ly-23+ subset of T small lymphocytes at all the sites examined. The absolute number of these two subsets also increased excepting the case of null cell rise in the thymus which was relative. The functional potentials of Lyt subsets were explored by employing in vitro and in vivo assays. While no appreciable levels of anti-turnout cytotoxic T cells (Tc) were detectable by a 51Crk release assay in the host spleen or the turnout-draining lymph nodes at any stage of growth of MPC-11 tumour, such Tc was generated in vitro by a co-cultivation of unprimed spleen cells with irradiated MPC-11 cells. These Tc were Thy-l+ and Ly-12+, as noted from antibody+C' mediated abrogation of cytotoxicity. These results suggested that the generation of anti-turnout Tc in vivo was suppressed in tumour-bearing hosts. The possibility of a cell-mediated suppression was tested by an adoptive transfer of thymocytes or splenocytes from turnout-bearing mice into naive or pre-immunized recipients which then received fresh turnout transplants. This procedure caused a specific enhancement of turnout growth in three tumour-host combinations: MPC-I 1 or WEHI-164 turnout in BALB/c mice and W-I fibrosarcoma in CBA mice. The suppressor lineage lymphocytes appearing in vivo were found to be Thy-1+ and Ly-1-, 2+, as noted from antibody +C' mediated abrogation of their turnout-growth promoting ability. They appeared earlier (7 days) in the thymus and later (> 2 weeks) in the spleen and then persisted during the turnout lifetime. The parallel kinetics of the increase in the overall level of Ly-23+ cells and the appearance of Ly-2(3)+ suppressor lineage T cells in tumour-bearing hosts may indicate that studies of T-cell surface markers may be useful in predicting changes in the functional lymphocyte subsets. [ABSTRACT FROM AUTHOR]

Synergy can be observed in the proliferative response to mitogens of cultures containing human T and Null cells when compared with those containing only highly purified cells of those two types. This synergy was analysed (i) by evaluation of the proliferative response at each step of the purification process leading to separation of T and Null cells; (ii) by back-mixing T and Null cells at different ratios; and (iii) by evaluation of the proliferative response of free suspension cultures of T cells overlaying a semi-solid layer containing Null cells, or of free suspension cultures of Null cells over a semi-solid culture layer of T cells. The following conclusions were reached: (i) purified Null cells are unresponsive to mitogen when cultured alone or in the presence of diffusible T-cell products; (ii) the T cells are less responsive when cultured alone than in the presence of Null cells or diffusible Null cell products. Thus the synergistic effect observed between T and Null cells is not due to the promotion of Null-cell proliferation by T-cell products but can be accounted for by diffusible Null-cell products enhancing the process of T lymphocyte activation by mitogens. [ABSTRACT FROM AUTHOR]

Human lymphocytes precultured for 24–48 hr form more T-lymphoid colonies (LT-CFU) in agar than do fresh cells. It appears that during the preculture period lymphocytcs proceed from Go to the next S phase, a process that is dependent upon active cellular metabolism. Thus, lymphoproliferation as assayed by LT-CFU growth appears to be controlled by short-lived suppressor cells (SLSC) which may be similar to those described for blastogenesis evaluated by thymidine incorporation assay. The activity of SLSC operating in LT-CFU system may be controlled by prostaglandins. [ABSTRACT FROM AUTHOR]

Mixed culture of nylon non-adherent (T-enriched) spleen cells or lymph node cells of ACI/N or F344 rats with mitomycin C-treated autologous spleen cells resulted in the increased DNA synthesis of the responder T cells when they were cultured in medium containing foetal calf serum (FCS) or bovine Serum albumin. This autologous mixed lymphocyte reaction (AMLR), however, proceeds little when the cells were cultured in medium containing autologous or allogeneic rat serum, irrespective of the responder:stimulator cell ratio and to the culture period. Furthermore, the AMLR response in FCS was greatly reduced if a relatively large number of macrophages were present in the responder cell population. These results suggest that the AMLR response is unlikely to occur in a physiological condition or in [ABSTRACT FROM AUTHOR]

The differential effects of in vitro cyclophosphamide (CY) on subpopulations of normal human peripheral blood lymphocytes involved in the pokeweed mitogen-induced plaque-forming cell (PFC) response against sheep red blood cells were examined. It was found that the plaque-forming B cells in this system are sensitive to CY over a wide concentration range including concentrations which have a minimal effect on overall cell viability. Kinetic experiments revealed that CY exerts its inhibitory effect on the PFC response only if added very early in culture. Thus, it appears that in vitro CY must exert its inhibitory influence on an early phase of polyclonal B-cell activation. When T-cell enriched (TCE) populations were incubated overnight with high concentration CY and then added back in co-culture to fresh autologous B cells, significant enhancement of PFC responses was observed suggesting a selective inhibition or elimination of a regulatory suppressor cell population found in ICE lymphocyte preparations. Helper T cells are relatively resistant to the inhibitory actions of CY. Thus, human B cells appear to be most sensitive to CY, followed in sensitivity by the suppressor cell populations in the 1-cell fraction with relative resistance of the helper T cells. These observations have direct relevance in understanding the mechanisms of selective action of CY on normal human lymphocyte subpopulations with possible application to disease states in man. [ABSTRACT FROM AUTHOR]

Female mice of the NMRI strain were injected with 5 μg diethylstilboestrol (DES) or oestradiol-17β for the first 5 days after birth. Controls were given olive oil only. At the age of 4–6 months, the spleen lymphocyte population from the DES females had about half the percentage of cells undergoing capping after exposure to concanavalin A (Con A) as controls. The results from the oestradiol-injected females varied. After treatment of lymphocytes from DES females with colchicine, the percentage cells capping was as in control females. Binding studies did not reveal any difference in Con A receptor affinity or receptor number between DES females and controls. [ABSTRACT FROM AUTHOR]

The effect of neuraminidase (from Cl. perfringens, CPN) on the human lymphocyte response to pokeweed mitogen (PWM) was studied. CPN treatment greatly increased [3H]-thymidine incorporation by human lymphocytes at lower concentrations of PWM. This enzyme acted specifically on T-cell proliferation and had no direct effect on non-T-cell proliferation. When CPN-treated non-T cells were added to autologous T cells, [3H]-thymidine incorporation was markedly enhanced at lower concentrations of PWM. However, the addition of T cells pre-treated with mitomycin C (MMC) to CPN-treated non-T cells failed to increase [3H]-thymidine incorporation in contrast to the controls. MMC-blocked, CPN-treated non-T cells significantly enhanced T-cell proliferation, whereas the effect of MMC-blocked, CPN-treated adherent ceils was equal to that of the controls. These data indicate that cell-surface properties of non-T cells other than monocytes affect T-cell proliferation in some situations. [ABSTRACT FROM AUTHOR]

Nude and normal CBA mice have been used in adoptive transfer experiments to analyse the development of immunological memory. The development of B-cell memory to xenogeneic erythrocyte antigens is to a very large degree dependent on the presence of T cells, wit h IgG memory being somewhat more dependent than IgM memory. In this system, the expression of B memory, that is the transformation of memory cells to antibody-secreting cells under the inductive influence of antigen, is largely dependent on the presence of T cells. Primed (educated) T cells can have an antigen-specific potentiating effect on unprimed B cells in the presence of antigen. [ABSTRACT FROM AUTHOR]

An investigation was made of the proxies of cytotoxic T cells induced by Con A and exposure to LCM virus-infected cells. As a basis for such studies, the optimal conditions for in vitro Con A stimulation of in vivo LCM virus-primed C3H mouse splenocytes were determined. The most potent cytoxicity was obtained when responder cells were cultured in the presence of Con A in a concentration of 2 μg/ml for 3 days, but strong cytoxicity was also measured on days 2 and 4 When stimulation was performed by the homologous antigen maximal response was seen on day 4 although marked cytotoxicity was also noted on day 3. Effector cells produced by the two different procedures showed equally high degrees of cytotoxicity against LCM virus-infected target cells, whereas they did not appear cytotoxic against non-infected targets. If LCM virus-immune mice were treated intravenously with 280 μg of Con A per animal, moderate cytotoxicity was demonstrable in splenocytes from these mice 1, 2 and 3 days after treatment. The in vitro generation of secondary cytotoxicity by Con A as well as by the homologous antigen was found to be totally dependent on DNA synthesis. The reactivated cells were investigated for in vivo anti-viral effect by measuring their ability to protect intracerebrally LCM virus-infected mice from a fatal outcome of this infection. LCM virus-primed splenocytes stimulated by the homologous antigen caused complete protection, while Con A-reactivated cells did not protect at all. Secondary cytotoxic cells stimulated by Con A and by LCM virus showed fairly similar in vitro characteristics, but fundamentally different in vivo qualities. [ABSTRACT FROM AUTHOR]

Non-specific acid α-naphthyl acetate esterase (ANAE) activity was demonstrated m a majority of bovine peripheral blood lymphocytes, confirming and extending the observations on murine and human lymphocytes made by previous workers. Simultaneous study of both ANAE activity and spontaneous crythrocyte (E) or erythrocyte-antibody-complement (EAC) rosetting capability of the same bovine lymphocytes showed directly that, while 64.2 ± 4.9 (SEM) % of bovine lymphocytes capable of forming E rosettes were ANAE positive, 38.3 ± 0.8% of those forming EAC rosettes were also A NAE positive. Similar studies of human peripheral blood lymphocytes showed also that, while 80.6 ± 2.2% of the lymphocytes capable of forming E rosettes were ANAE positive, 44.1 ± 2.6% of EAC forming lymphocytes were ANAE positive. Thus the presence of ANAE activity in a majority of T lymphocytes and a significant proportion of B lymphocytes of both human and bovine peripheral blood is indicated. Human and bovine lymphocytes from phytohaemagglutinm (PHA)-stimulated cultures demonstrated greatly enhanced intensity of ANAE activity. [ABSTRACT FROM AUTHOR]

The ability of small and large T precursor cell pools to differentiate into mature functional T lymphocytes on thymus feeder cell layers or in the presence of a supernatant prepared from such feeder layers was compared. Evidence was obtained showing that the small cell pool differentiated as effectively in the presence of soluble factors prepared from the thymus cultures as in the presence of the thymus cells themselves. In contrast, large stem cells apparently needed cellular contact with the thymus feeder cultures in order to promote differentiation, though a time point could be found at which further differentiation from this precursor pool would also occur in the presence of the thymus culture supernatant only. These data concurred with evidence from in vivo experiments for two pools of T-cell precursors which differentiated in thymectomized or thymus-intact recipients respectively. [ABSTRACT FROM AUTHOR]

Following the implantation of syngeneic chromosomally marked thymuses under the kidney capsule of normal adult mice, donor T cells were found in the blood and other lymphoid organs. The mice were found to have increased numbers of Thy.1-pusitive cells in spleen and lymph nodes, increased peripheral blood lymphocyte levels and also augmented immune responses to sheep erythrocytes. The contribution made by an individual graft to the donor T cell pool was independent of the number of thymuses grafted as was the growth of the grafts themselves. The results reaffirm that there is no homeostatic feedback control of thymus growth in adult mice. [ABSTRACT FROM AUTHOR]

Lymphoid cells from human palatine tonsils were identified on tissue sections by membrane or intracellular immunofluorescence (IF) staining. Used in an indirect technique, an anti-IgM and an anti-HTLA (human T lymphocyte antigen) antiserum gave complementary patterns of membrane IF, characteristic of the follicular organization. When serial sections were stained for each of the five classes, immunoglobulin-containing cells from all classes were found. Their relative frequencies were, in decreasing order: IgG: 61·6%; IgA: 17·3%; 1gM: 12%; IgE: 7·5%; IgD: 1·6%. These differed from those of the gut-associated lymphoid tissue (IgA>IgG>IgM) and of the peripheral lymph nodes (IgG>IgM>IgA), but were close to those of mesenteric nodes. The absence of secretory component in tonsil was an additional difference from gut-associated lymphoid tissue and the relatively high proportion of 1gB-containing cells, in the absence of recognized atopy, is another feature in common with mesenteric lymph nodes. Finally, slight differences between these results and those obtained on tonsil cell suspensions suggest that some degree of selection probably occurs during the isolation procedure. [ABSTRACT FROM AUTHOR]

The response to SPA and Staphylococcus strain Cowan I (StaCw) of highly purified populations of peripheral blood and tonsil human lymphocytes was investigated. Purified T lymphocytes isolated from peripheral blood by E-rosetting were unable to respond in vitro to StaCw and showed a poorly significant response to soluble SPA. On the contrary B-cell-enriched suspensions of either peripheral blood or tonsil responded well to StaCw. Either EA-RFC or EA-RFC-depleted suspensions showed a significant response to soluble SPA, but only EA-RFC-depleted suspensions were activated by StaCw. Highly purified B-cell populations from tonsils did not show any proliferative response in the presence of soluble SPA. The addition to highly purified B-cell suspensions from human tonsils of increasing concentrations of autologous T lymphocytes did not induce any increase of thymidine uptake in the presence of StaCw. However, it was able to restore a marked proliferative response of the B-cell cultures to soluble SPA, even though mitomycin-treated T lymphocytes were added. The low response of highly purified peripheral blood T lymphocytes to soluble SPA could be potentiated by the addition of autologous mitomycin-treated B cells, whereas the unresponsiveness of purified T lymphocytes to StaCw was not affected. Mitogenic activity of SPA coupled to Sepharose beads was different from that of soluble SPA and paralleled that of StaCw. These data strongly suggest that insoluble SPA is a T-cell-independent B-cell mitogen in man, whereas soluble SPA, like PWM, exerts its activity on B cells only in the presence of T cells. [ABSTRACT FROM AUTHOR]

A surprisingly high proportion of antibody (IgG) sensitized Chang liver ceils apparently contained one or more intracytoplasmic human peripheral blood lymphocytes following a period of contact at 37°. Since various technical factors were found to influence this phenomenon of lymphocyte ‘emperipolesis’, optimum conditions were selected for use in a standard quantitative in vitro assay. Lymphocytes from normal individuals varied considerably in their ability to participate in emperipolesis; an observation which suggested that a particular lymphocyte subpopulation may be involved, Preliminary characterization of emperipoletic cells indicated that they are Fc receptor bearing, non-T lymphocytes. The significance of these findings in relation to immune mechanisms is discussed. [ABSTRACT FROM AUTHOR]

The primary and secondary responses to ∅X174 have been studied in T cell-deprived (T-) and control CBA mire including sham-operated (T+) and normal mice. The effect of pertussis on the immune response of these mice has been measured. It is concluded that: (1) the γG and memory responses to ∅X are produced in T - mire even though greatly reduced in comparison with T+ and normal mice; (2) pertussis appears to enhance the γG response in T- mice while suppressing it in T + and normal mice. [ABSTRACT FROM AUTHOR]

Focuses on the collaboration between T- and B-cells in immunology. Mechanism of T-B-cell interaction; Nature of the T-helper cell receptor; Phase of B-cell differentiation.