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Biomedical subjects

E M Shevach

Publications and source records attributed to E M Shevach.

At least 163 records · Page 9Linked to original sources
PubMed1983

Stimulation of T-cell activation by UV-treated, antigen-pulsed macrophages: evidence for a requirement for antigen processing and interleukin 1 secretion.

The nature of the defect(s) in the ability of UV-treated guinea pig macrophages to stimulate the proliferative response of guinea pig T cells to soluble protein antigens was investigated. T cells proliferated vigorously when cultured with peritoneal exudate cells (PEC) which had been pulsed with soluble protein antigens, but failed to proliferate when cultured with soluble antigen or with antigen-pulsed, UV-treated PEC. UV-treated macrophages were unable to secrete interleukin 1 (IL-1). Addition of IL-1 partially restored the T-cell proliferative response stimulated by antigen-pulsed, UV-treated PEC. However, IL-1 was able to restore such a response only when the PEC were pulsed with antigen before being exposed to UV. Similar results were obtained when antigen-pulsed PEC were used to stimulate T cells to secrete interleukin 2 (IL-2). These results demonstrate that UV-treated macrophages are defective both in their ability to properly process and present antigen for T-cell recognition and in their ability to secrete IL-1.

Animals↗
PubMed1983

Production and properties of monoclonal antibodies to guinea pig Ia antigens.

Although the use of monoclonal antibodies to characterize the Ia antigen system is still in its infancy, the usefulness of this approach is clearly apparent. Since xenogeneic immunization can be used to generate these antibodies, the chances are good that a greater variety of Ia types and determinants will be detected compared to those detected with conventional alloantisera. In addition, the advantages of unlimited quantity and constant specificity allow a much greater degree of standardization than was previously possible. Finally, monoclonal antibodies open up lines of investigation, such as the examination of correlations between the monoclonal antibody's inhibition of T-cell proliferation and the antibody's corresponding Ia epitope-binding characteristics, that it would be impossible to approach using conventional alloantisera.

Animals↗
PubMed1983

Identification and initial characterization of a rat monoclonal antibody reactive with the murine interleukin 2 receptor-ligand complex.

Xenogeneic monoclonal antibodies were prepared to the murine interleukin 2 (IL-2)-dependent HT2 cell line. One rat IgM monoclonal antibody (7D4) was identified that inhibited proliferation of the HT2 cells and of IL-2-dependent CTLL cells in the presence of crude rat IL-2 as well as of purified human IL-2. The level of inhibition was dependent on both antibody and IL-2 concentration. Cell distribution studies using a fluorescence-activated cell sorter showed that the antigen identified by 7D4 is expressed at a high density on HT2 cells and on concanavalin A (Con A)-induced T-cell blasts and at a substantially lower density on lipopolysaccharide-induced B-cell blasts; 7D4 binding was not detected on greater than 95% of nonactivated thymocytes, T cells, or B cells. Competition binding studies indicated that 7D4 fails to inhibit the binding of 3H-labeled human IL-2 to CTLL cells. However, 7D4 specifically immunoprecipitated 3H-labeled human IL-2 from detergent extracts of HT2 cells or Con A-induced T-cell blasts that had been pulsed with [3H]IL-2; in contrast, 7D4 did not react with free [3H]IL-2. Initial biochemical analysis of immunoprecipitates with 7D4 of detergent extracts from surface-iodinated Con A-activated spleen cells showed a major band having apparent molecular weight of 48,000-62,000. Collectively, these results suggest that 7D4 detects an epitope on the IL-2 receptor distal to the ligand binding site or another molecule that physically associates with the receptor.

Animals↗
PubMed1983

Induction of transplantation tolerance in guinea pigs by spleen allografts. III. Transfer of tolerance to normal hosts.

Spleen allografts from (2 X 13)F1 donors survive indefinitely in immunologically intact strain 2 recipients. Such strain 2 hosts with long-term surviving F1 grafts had markedly suppressed anti-13 MLR responses and cells capable of suppressing the response of normal strain 2 cells to strain 13 stimulators were present in some long-term surviving animals. In order to further analyze the cellular basis for this tolerant state, we transferred cells from tolerant donors to normal syngeneic strain 2 hosts. We showed that such suppressor cells transfer MLR unresponsiveness to primary or secondary hosts, but that the period of MLR suppression is rather short-lived. Strain 13 cardiac allografts survived indefinitely in cell-transferred primary or secondary hosts and further enhanced MLR suppression, whereas most cardiac allografted controls had vigorous MLR responses for strain 13 stimulator cells after rejection of their transplants. Attempts to abrogate established tolerance in transferred hosts, either by donor antigen or by host cytolytic T cells were unsuccessful.

Animals↗
PubMed1983

Subsets of epidermal Langerhans cells as defined by lectin binding profiles.

In this study we characterize the cell surface glycoconjugate moieties of strain 2 guinea pig epidermal Langerhans cells (LC) in single cell suspension by using a battery of 17 fluorescent lectins. All LC displayed binding sites for concanavalin A, succinylated concanavalin A, Lens culinaris agglutinin, Pisum sativum agglutinin, wheat germ agglutinin, succinylated wheat germ agglutinin, Griffonia simplicifolia agglutinin I, Ricinus communis agglutinin I, Phaseolus vulgaris E agglutinin, and Phaseolus vulgaris L agglutinin, but failed to bind Sophora japonica agglutinin (SJA), Dolichos biflorus agglutinin (DBA), and Ulex europaeus agglutinin I (UEA I). Neuraminidase pretreatment rendered LC reactive for SJA, but not for DBA and UEA I. The binding profiles of certain lectins point to the existence of LC subpopulations in that Griffonia simplicifolia I-B4 isolectin, peanut agglutinin (PNA), Helix pomatia agglutinin, and soybean agglutinin bound to only 80% (range 70-90%) of Ia-positive epidermal cells; binding sites for these lectins on primarily unreactive Ia-positive cells were unmasked when epidermal cells were treated with neuraminidase prior to lectin labeling. Ultrastructural PNA labeling studies revealed that the vast majority of Birbeck granule-containing LC displayed PNA binding sites, whereas indeterminate cells were consistently PNA-negative. Identification of carbohydrate configurations expressed on LC surfaces by lectin binding may provide a clue for the elucidation of the mechanisms of established LC functions and possibly the discovery of as yet unknown properties of this cell type.

Animals↗
PubMed1983

Cyclosporin A-treated guinea pig responder cells secrete a genetically restricted factor that suppresses the mixed leukocyte reaction.

Cyclosporin A (CY A) is a hydrophobic, undecapeptide, fungal metabolite with potent immunosuppressive effects on T lymphocyte-mediated immune responses. Suppressor T lymphocytes generated during a mixed leukocyte reaction (MLR) performed in the presence of CY A, release a factor that suppresses a primary MLR of responder T cells, which is derived from the same strain as the factor producer but lacks specificity for the stimulator cell. These results suggest a finely regulated pathway by which CY A may induce and maintain a permanent state of transplantation tolerance in vivo.

Animals↗
PubMed1983

Identification of a membrane antigen that is distinct from the interleukin 2 receptor and that may be required for interleukin 2-driven proliferative responses.

During the course of studies designed to raise murine monoclonal antibodies to a guinea pig alloreactive T cell line, an IgM monoclonal antibody (5C3) was identified that completely inhibited the alloantigen and IL 2-dependent proliferative response of the immunizing colony and other alloreactive T cell colonies with different antigen specificities. Tissue distribution on the FACS demonstrated that the surface antigen defined by 5C3 was preferentially expressed on T cells activated by mitogen, alloantigen, or antigen. 5C3 was also a potent inhibitor of alloantigen- and antigen-induced T cell proliferation. In addition, 5C3 substantially inhibited the proliferative response of guinea pig Con A-induced blast cells to guinea pig IL 2-containing culture fluids and to a preparation of partially purified human IL 2 but was a poor inhibitor of mitogen-induced T cell proliferation. Blast cells obtained from the co-culture of mesenteric lymph node cells with Con A in the presence of 5C3 lacked the surface molecule defined by 5C3. The 5C3- and 5C3+ blast populations, nevertheless, absorbed equivalent amounts of IL 2, which suggested that 5C3- blasts were not deficient in the expression of IL 2 receptors. However, 5C3- blast cells failed to proliferate in response to IL 2-containing culture fluids. Furthermore, 5C3 had no inhibitory activity on either the binding or subsequent degradation of radiolabeled human IL 2 by guinea pig IL 2 receptors. These data suggest that 5C3 recognizes a component of a putative IL 2 receptor-effector complex distinct from the IL 2 receptor and that this molecule plays a critical role in the processing or generation of the growth signal IL 2 transmits to T lymphocytes.

Animals↗
PubMed1983

Fine specificity of cloned insulin-specific T cell hybridomas: evidence supporting a role for tertiary conformation.

Two groups of cloned insulin-specific T cell hybridomas were derived from the fusion of (BALB/c X A/J)F1 T cells with the BW5147 tumor line. Group I responded only to the immunogen pork insulin and failed to respond to rat insulin, which differs only at amino acids A4 and B3. The second group of T cell hybridomas exhibited a broader pattern of reactivity to heterologous insulins because they could be stimulated with the B chain-identical pork, beef, sheep, and human insulins, as well as by isolated oxidized B chain. These hybridomas, however, displayed a much greater reactivity to pork insulin than to beef insulin or to the oxidized B chain. Comparison of the reactivity profiles of these two groups of hybridomas with the three-dimensional structure of the insulin molecule strongly suggested that group I cells were recognizing an immunogenic moiety composed of residues A4 and/or B3 in association with A chain loop determinants and that group II hybrids recognized a moiety composed of the amino acid sequence of the B chain and the A chain loop. Both groups of hybrids were restricted to the high-responder I-Ad allele but could be distinguished by their pattern of alloreactivity. We were unable to show any effect of a panel of monoclonal anti-insulin antibodies on the induction of interleukin 2 secretion by these hybridomas or to demonstrate the presence of idiotypic determinants on these T hybrids by using a panel of anti-idiotypic reagents raised against the monoclonal anti-insulin antibodies.

Animals↗
PubMed1983

T cell clones and hybridomas as probes for the analysis of the syngeneic mixed leukocyte reaction.

We have prepared short term T cell lines, long term T cell lines from soft agar colonies, and SMLR specific T cell hybridomas. Analysis of these populations has shown that the SMLR responsive T cell population is not specific for a foreign serum component, but rather represents a T cell population which can be polyclonally activated by self-Ia antigens. It is likely that some antigen specific cells are found within this autoreactive subpopulation.

Animals↗
PubMed1982

Production of autoreactive I region-restricted T cell hybridomas.

We produced autoreactive T cell hybridomas that can be induced to secrete interleukin 2 by co-culture with either syngeneic splenic stimulator cells or syngeneic Ia-positive B cell-B lymphoma hybridomas. These autoreactive hybridomas arose from the fusion of pork insulin-primed lymph node T cells with the AKR thymoma BW 5147 and occurred at a higher frequency than the expected insulin-specific hybridomas. Mapping studies using recombinant strains and blocking studies using monoclonal anti-Ia antibodies localized the stimulatory determinant to the I-Ad subregion of the major histocompatibility complex. These T cell hybridomas did not appear to be directed at any foreign antigen present in the culture system because activation occurred in serum-free, insulin-free medium (Iscove's medium). Such hybridomas should prove to be a potent tool in studying the biologic significance and function of the autoreactive response.

Alleles↗
PubMed1982

Generation of T cell colonies from responder strain 2 guinea pigs that recognize the copolymer L-glutamic acid, L-lysine in association with nonresponder strain 13 Ia antigens.

T cells from nonimmune responder strain 2 guinea pigs were primed in vitro to the copolymer GL in association with allogeneic, nonresponder strain 13 PEC. T cells that recognized GL in association with strain 13 Ia were separated from alloreactive T cells by cloning the population in soft agar following the priming in liquid culture. The existence of T cells of responder origin that recognize antigen in association with nonresponder macrophages is most consistent with clonal deletion models of Ir gene function.

Animals↗
PubMed1982

Nature of the antigenic complex recognized by T lymphocytes. VIII. Specific inhibition of the stimulatory capacity of antigen-pulsed hapten-modified peritoneal exudate cells by anti-hapten antibody.

When macrophages which were pulsed with soluble protein antigens and then modified with 2,4,6-trinitrobenzenesulfonic acid (TNBS) were cultured with primed T cells in the presence of anti-2,4,6-trinitrophenyl (TNP) antiserum, a marked inhibition of the T cell proliferative response specific for the soluble protein antigen under study was observed. Inhibition of the proliferative response required that the protein antigen under study be easily susceptible to conjugation with TNBS. A lag period of 1-3 h must elapse following pulse exposure to the protein antigen and prior to TNP modification for anti-TNP antibody to exert an inhibitory effect, which suggests that processing of antigen in an intracellular site might occur with subsequent reexpression of antigen on the macrophage surface. It was hypothesized that anti-TNP antibody inhibits T cell proliferation by capping and shedding of TNP-modified determinants of the nominal antigen as well as TNP-modified cell surface proteins from the macrophage membrane. The failure of others to demonstrate an effect of anti-antigen antibody on T cell activation can best be explained as secondary to the low density of antigenic determinants on the macrophage membrane with resultant low-affinity binding of antibody to antigen.

Animals↗
PubMed1982

Nature of the antigenic complex recognized by T lymphocytes. IX. Direct immunochemical demonstration of nominal antigen on the macrophage cell surface.

As an initial approach to macrophage (M phi) antigen handling, guinea pig M phi pulsed with the radiolabeled terpolymer L-glutamic acid, L-lysine, L-tyrosine (GLT) were modified with the cell surface-specific probe 2,4,6-trinitrobenzenesulfonic acid either immediately after pulsing (fresh) or 24 h after pulsing (aged); nonidet P-40 extracts were prepared from these cells and analysis of these extracts with anti-trinitrophenyl antisera was performed in a quantitative radioimmunoassay. Such experiments indicated that fresh GLT-pulsed M phi contained a pool of intracellular GLT as well as a distinct pool of cell surface GLT. In contrast, aged GLT-pulsed M phi lacked intracellular GLT but expressed GLT on the cell surface. In addition, a pool of cell surface GLT was also detected on Ia-M phi and on M phi from guinea pigs which were nonresponders to GLT. Thus, this study provides a direct demonstration of the presence of exogenous antigen on the M phi cell surface. However, the cell surface expression of GLT does not appear to be an exclusive property expressed by functional Ia+ antigen-presenting M phi.

Animals↗
PubMed1982

Induction of transplantation tolerance in guinea pigs by spleen allografts. I. Operative techniques and clinical results.

Four hundred and ten heterotopic spleen transplants were performed in inbred guinea pigs of strains 2 and 13 whose major histocompatibility complex differs only in the I region and which rapidly reject reciprocal skin allografts. Spleen allografts from strain 13 to strain 2 survived throughout the lifetime of the hosts, whereas spleen allografts from strain 2 to strain 13 were rejected within 3 weeks. Animals not rejecting their spleen transplants were specifically tolerant of donor strain skin allografts. Strain 2 recipients of strain 13 spleen grafts had a surprising high mortality from graft-versus-host disease which peaked at 6 weeks after transplantation.

Animals↗
PubMed1982

Induction of transplantation tolerance in guinea pigs by spleen allografts. II. Responses in the mixed leukocyte reaction correlate with the tolerant state.

We have developed a model for the induction of transplantation tolerance in the guinea pig by vascularized spleen allografts. Spleen allografts from strain 13 to strain 2 hosts frequently survived in healthy recipients without clinical GVHD or induced clinical GVHD. (2 x 13)F1 to strain 2 spleen allografts survived indefinitely without inducing GVHD. In contrast, strain 2 spleen allografts were rejected by strain 13 hosts. An excellent correlation was observed between the clinical course and the degree of reactivity to donor strain stimulator cells in the MLR. Animals that had rejected their grafts had normal or enhanced proliferative responses in the MLR. Strain 2 hosts with long-term surviving strain 13 or (2 x 13)F1 grafts had markedly suppressed anti-13 responses. Animals with GVHD had a suppressed MLR toward donor strain stimulator cells with simultaneous reactivity to host strain stimulator cells. Cells capable of suppressing the response of normal host strain cells to donor strain stimulators were present in some long-term surviving animals and may be responsible in part for the maintenance of the tolerant state.

Animals↗
PubMed1982

Effect of cyclosporin A on T cell function in vitro: the mechanism of suppression of T cell proliferation depends on the nature of the T cell stimulus as well as the differentiation state of the responding T cell.

We have studied the effects of the immunosuppressive agent cyclosporin A (CY A) on T cell activation in the guinea pig both in the presence and in the absence of exogenous interleukin 2 (IL 2). CY A suppressed T cell activation by the mitogen, concanavalin A, by blocking IL 2 production and not by blocking the induction of IL 2 receptors. In contrast, the primary T cell proliferative responses to self-Ia antigens in the syngeneic mixed leukocyte reaction (SMLR) and to trinitrophenyl-modified syngeneic macrophages were blocked by CY A and this suppressive effect could not be corrected by addition of exogenous IL 2. T cells primed to syngeneic stimulator cells in the presence of CY A failed to develop IL 2 responsiveness even in the presence of exogenous IL 2, suggesting that CY A directly blocked induction of IL 2 receptors on the responding T cell population. In contrast, the secondary SMLR was suppressed by CY A in the absence of IL 2, but was normal when IL 2 was added to the cultures. CY A completely blocked the primary allogeneic MLR but this inhibitory effect could be reversed when exogenous IL 2 was added to the cultures. Moreover, in the presence of exogenous IL 2, CY A had no effect on the development of IL 2 responsiveness by alloreactive T cells. In addition, CY A induced a population of radiosensitive cells with suppressor activity for the primary MLR. Thus, in the guinea pig, CY A inhibits Ti cell activation both by blocking IL 2 production as well as by inhibiting the induction of IL 2 responsiveness. These two effects occur in the same range of CY A concentrations and are differentially dominant depending on the nature of the stimulating signal and the differentiation state of the responding T cell.

Animals↗