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E M Shevach

Publications and source records attributed to E M Shevach.

At least 73 records · Page 4Linked to original sources
PubMed1993

Molecular characterization of the early activation antigen CD69: a type II membrane glycoprotein related to a family of natural killer cell activation antigens.

CD69 is a disulfide-linked homo-dimer expressed on the surface of activated T cells, B cells, natural killer cells, neutrophils and platelets. Antibody crosslinking of CD69 in the presence of phorbol ester results in cellular activation events including proliferation and the induction of specific genes. Using an expression cloning strategy we have isolated cDNA encoding human CD69 from a CD4+ T cell clone. Transfection of the cDNA clone in CV-1/EBNA cells results in the expression of a covalently linked homodimer. The cDNA insert hybridizes to a 1.7-kb mRNA in phorbol 12-myristate 13-acetate- or phytohemoagglutinin-stimulated human T cells. Using the human clone we have isolated cDNA encoding mouse CD69, which, when expressed in human T cells allowed those cells to respond to anti-mouse CD69 antibodies by secreting interleukin-2 and interferon-gamma. Sequence analysis showed that both mouse and human CD69 are type II membrane glycoproteins related to the NKR-P1 and Ly-49 families of natural killer cell activation molecules.

Amino Acid Sequence↗
PubMed1993

Influence of bromocriptine administration to mothers on the development of pup thymocyte and splenocyte subsets and on mitogen-induced proliferation in the mouse.

The influence of prolactin (PRL) on the development of the immune system in the mouse was studied by injecting mothers with bromocriptine (CB-154) to produce hypoprolactinemic milk. Alterations in pup thymocyte and splenocyte cell subsets were observed to graded doses of CB-154 administered to mothers. There was an increase in the relative percentages of neonate thymic CD4 and CD8 cells at 5 days of age when mothers were injected with 100 micrograms of CB-154 2 x daily from day 1 to 5 of lactation, however, there was no alteration in absolute thymic subset cell numbers. The relative percentage of pup spleen CD4, CD8 and B cells were increased when mothers were administered 50 or 100 micrograms of CB-154 and the 50 micrograms dose resulted in a significant increase in the absolute number of CD4 cells while the 100 micrograms dose induced a significant decrease in the three splenic cell subsets examined. Graded doses of CB-154 administered to mothers resulted in decreases in the PRL concentration of stomach milk as measured by the Nb2 cell proliferation assay. The serum PRL level of the pups, however, was not altered by any dose of CB-154 injected to the mothers. The administration of PRL to pups nursing mothers given the 100 micrograms dose of CB-154 did not alter the pup thymocyte and splenocyte subset population from that of litter-mate controls. The administration of mouse PRL and mouse growth hormone antisera to pups nursing saline-injected mothers did not alter thymocyte and splenocyte subsets from that of saline-injected litter mate controls. The proliferation of neonatal thymocytes by Con-A stimulation was not altered by CB-154 injection to mothers and PRL administration to pups. However, since the percentage of thymic CD4 and CD8 cells in the thymus was increased 2 to 3 fold, the apparent lack of effect was in fact a decrease in the responsiveness of the thymocytes. Con-A stimulation of neonatal splenocytes resulted in a significant increase in proliferation for mothers administered CB-154 in keeping with the increase relative percentage of CD4 and CD8 cells observed. Prolactin administration to the pups did not alter the response. LPS stimulation of neonatal splenocytes increased the proliferation of B cells taken from pup nursing mothers administered CB-154 and PRL administration appeared to partially block this proliferation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Do parasitic infections break T-cell tolerance and trigger autoimmune disease?

Burnet and Fenner originally defined 'tolerance' as 'unresponsiveness against self'. It is now generally accepted that the phenomenon of tolerance is required to protect on individual from potentially autoreactive cells. Recent experiments have independently shown that parasite infection or interleukin 2 (IL-2) can reverse an established T-cell tolerance in vivo. Breaking T-cell tolerance restores the capacity of T cells to be stimulated by their specific antigen and, in the case of a self-antigen, may be followed by autoimmune disease. In this review, Martin Röcken and Ethan Shevach briefly describe the potential pathways for generating T-cell tolerance in vivo, and focus on recently described mechanisms by which parasitic infections may circumvent or abrogate the tolerant state.

Journal Article↗
PubMed1993

Gamma delta T cells promote CD4 and CD8 expression by SCID thymocytes.

Molecular studies of the gamma delta TCR, which is expressed by a minor subpopulation of T lymphocytes in all vertebrate species, have defined a subset which expresses a receptor with extreme junctional diversity and a second subset, most commonly found in epithelia, which expresses a receptor of very limited diversity. In the developing murine thymus, gamma delta T cells appear in an ordered sequence of specific V rearrangements, V gamma 3V delta 1 on day 14, V gamma 2V delta 1 on day 17, and subsequently V gamma 4V delta 5, V delta 6, or V delta 7. We demonstrate that the transfer of expanded populations of gamma delta cells from newborn thymus and cell lines expressing the invariant V gamma 3V delta 1 receptor into SCID mice, which lack T and B cells, results in the appearance of CD3-CD4+CD8+ thymocytes. Thus, one role of the early appearing V gamma 3V delta 1 T cells in thymic development in vivo is to promote CD4 and CD8 surface expression on precursor cells.

Animals↗
PubMed1993

Identification by analytical flow cytometry of prolactin receptors on immunocompetent cell populations in the mouse.

Five monoclonal antibodies (T1, T6, U5, U6, and E21) made to the external portion of the rat PRL receptor (PRL-R) were conjugated to fluorescein isothyrocynate and used to examine the presence of PRL-R on mouse lymphocytes and macrophages using analytical flow cytometry. The monoclonals were initially evaluated using Nb2 cells, a cloned line from a rat lymphoma, and NOG-8 cells, a cloned line from normal mouse mammary gland tissue, which are known to have PRL-R. All monoclonal antibodies bound to these cells, but the U5 monoclonal gave the best separation from unstained cells. CTLL-2 cells, a mouse lymphoma cell line containing interleukin-2 receptors, did not bind to any of the monoclonals. Isolated thioglycolate-induced peritoneal macrophages contained PRL-R, and the PRL-R monoclonal U5 gave the best separation from unstained cells. Eighty-five percent of macrophages constitutively had PRL-R using this monoclonal. In vivo stimulation of the popliteal lymph node by the injection of Concanavalin-A (Con-A) into the right foot pad of intact and ovariectomized (OVX) BALB/c mice induced, at the end of 10-12 h, a marked increase in interleukin-2 receptor (IL-2R) expression on CD4, CD8, and B-cells compared to the unstimulated left popliteal lymph node. The number of CD4 and CD8 cells from OVX animals with IL-2R was twice that from intact animals, whereas no difference in the percentage of B-cells with IL-2R was evident. PRL-R were constitutively expressed on 5% of the CD4 cells and 20% of the CD8 cells and were increased in the Con-A-stimulated lymph node when examined with the U5 PRL-R monoclonal. A higher percentage of CD4 and CD8 cells from OVX animals constitutively expressed PRL-R, and when stimulated with Con-A, a further increase was observed compared to the level in intact animals. Using the U5 monoclonal, over 80% of the B220 cells constitutively expressed PRL-R; however, when T1, T6, and U6 monoclonals were examined, the percentage was considerably below (20%) than that observed for U5. Con-A stimulation did not alter the percentage of B220 cells expressing PRL-R. These results show the importance of identifying lymphocyte subsets and examining a number of PRL-R monoclonals in determining lymphocyte PRL-R expression on the surface of the cell.

Animals↗
PubMed1993

Post-thymectomy organ-specific autoimmunity: enhancement by cyclosporine A and inhibition by IL-2.

It has previously been shown that the administration of cyclosporine A to newborn mice results in the development of autoimmunity later in life. It has been proposed that the neonatal administration of cyclosporine A results in altered thymic selection or inhibition of the development of suppressor cells. In the present study, treatment of day 3 thymectomized C3H/HeN mice with cyclosporine A (20 mg/kg/day) for 9 d post surgery increased the prevalence of antigastric autoantibodies. In contrast, the administration of IL-2 (300-600 Units/g/day) for 7 days after thymectomy inhibited the development of antigastric antibodies. We hypothesize that CsA may act by causing transient lymphokine abnormalities in the extrathymic environment during the first few weeks of life which lead to the development of antigastric antibodies. In contrast to the inhibition of development of antigastric antibodies, the administration of a similar course of IL-2 produced only a transient suppression of diabetes in NOD mice. These results and other data suggest that diabetes in NOD mice is probably due to a different immunologic defect.

Animals↗
PubMed1993

Influence of prolactin and growth hormone on the activation of dwarf mouse lymphocytes in vivo.

The influence of recombinant bovine prolactin (PRL) and recombinant bovine growth hormone (GH) was examined on the popliteal lymph node (PLN) expression of interleukin-2 receptors (IL-2R) in female Snell dwarf mice and normal litter mates after concanavalin A footpad injection. The absolute number of PLN CD4+, CD8+, or B+ cells of dwarf mice was less than that observed for normal litter mates, but when adjusted for the difference in body weight, only the absolute number of B cells was lower in dwarf animals when compared with normal litter mates. The injection of PRL or GH did not alter the observation. The administration of recombinant bovine PRL to normal animals, but not recombinant bovine GH, increased the expression of IL-2R or unstimulated PLN CD4+ and CD8+ subsets. Hormone administration to dwarf animals, however, did not alter the expression of IL-2R on unstimulated PLN T cell subsets. PLN cells from dwarf animals were poorly activated in vivo after injection of concanavalin A and the level of IL-2R expression induced was only 50% of that seen in the PLN of normal animals. The administration of PRL and GH completely corrected the defective induction of IL-2R expression on PLN from dwarf animals after concanavalin A stimulation. These findings strongly suggest that PRL and/or GH play an important role at some stage of the T cell activation process in vivo. Further studies are needed to precisely identify the defect in the dwarf mice.

Animals↗
PubMed1992

Activation requirements of newborn thymic gamma delta T cells.

We have analyzed the requirements for the induction of proliferative responses by thymic CD4-CD8- gamma delta T cells. Enriched populations of CD4-CD8- thymocytes from newborn mice, purified by negative selection with anti-CD4, anti-CD8, and anti-TCR alpha beta mAbs were found to contain approximately 20% gamma delta T cells that were p55IL-2R-. When these cells were cultured with a panel of lymphokines (IL-1, -2, -4, and -7), a small response was observed to some of the cytokines tested individually; however, combinations of certain lymphokines (IL-1 + 2, IL-1 + 7, and IL-2 + 7) were found to induce significant proliferation and the selective outgrowth (75-90%) of gamma delta T cells. These cells were IL-2R+, remained CD4-, yet expressed variable levels of CD8. A limited analysis with specific anti-V gamma and V delta mAb suggested that there had not been a selective expansion of preexisting V gamma 2, V gamma 3, or V delta 4 populations in response to the stimulatory lymphokine combinations. Thymic CD4-CD8- gamma delta T cells were unresponsive to stimulation with immobilized anti-pan gamma delta mAb alone. However, in the presence of immobilized anti-pan gamma delta mAb and IL-1, IL-2, or IL-7, but not IL-4, a vigorous proliferative response was observed. Phenotypic analysis showed that 80 to 95% of the proliferating cells were polyclonally expanded gamma delta T cells, expressed the p55IL-2R, and the majority remained CD4-CD8-. Blocking studies with anti-IL-2R mAb showed that stimulation with anti-pan gamma delta + IL-1, but not anti-pan gamma delta + IL-7 was dependent on endogenously produced IL-2. Collectively, these studies suggest that the activation requirements of newborn thymic gamma delta T cells differ markedly from alpha beta T cells in that gamma delta T cells 1) respond to combinations of cytokines in the absence of TCR cross-linking, 2) can respond to TCR cross-linking in the presence of exogenous cytokines, 3) but are unable to activate endogenous cytokine production solely in the presence of TCR cross-linking.

Animals↗
PubMed1992

Infection breaks T-cell tolerance.

Clonal deletion or clonal anergy establish tolerance in T cells that bear potentially autoreactive antigen receptors. Here we report that concomitant infection with the nematode Nippostrongylus brasiliensis breaks an established T-cell tolerance induced by injection of mice with Staphylococcus enterotoxin B (SEB). CD4+ T cells from SEB-tolerant mice did not produce either interleukin-2 or interleukin-4 when challenged in vitro with SEB. N. brasiliensis infection of SEB-primed animals resulted in a normal expansion of SEB-tolerant CD4+V beta 8+ T cells in vivo as well as an equivalent increase of SEB-reactive, interleukin-4-producing CD4+V beta 8+ T cells both in SEB-tolerant and in normal animals. Thus, infection with N. brasiliensis circumvented the tolerance established with SEB. Activation of anergic, potentially autoreactive CD4+ T cells by infectious agents seems to be a major pathway for the initiation of autoimmune diseases. Our results suggest that infectious agents may break tolerance in potentially autoreactive CD4+ T cells by activation of alternative reaction pathways.

Animals↗
PubMed1992

Secretion of a soluble, chimeric gamma delta T-cell receptor-immunoglobulin heterodimer.

Soluble derivatives of T-cell antigen receptors (TCRs) should prove invaluable for studying the interaction of these receptors with antigens and major histocompatibility complex molecules, for structural studies, and for the identification of unknown ligands. We have engineered chimeric proteins, containing the extracellular domains of the mouse V gamma 1.1-C gamma 4 and V delta 6.2-C delta (V, variable; C, constant) TCR chains fused to the hinge region, CH2 (H, heavy), and CH3 domains of human IgG1 heavy chain, and expressed them by transient transfection in COS cells. We show here that TCR gamma-IgH and TCR delta-IgH chimeric chains are produced intracellularly in significant amounts, that the two chains can assemble correctly to form disulfide-linked, glycosylated heterodimers, and that a selective mechanism allows secretion of correctly paired receptor chains into the medium. Identity of the chimeric secreted TCR gamma delta-IgH heterodimer was confirmed by immunoblot analysis using V gamma 1-specific anti-peptide antiserum and immunoprecipitation analysis using the monoclonal antibody UC7, which is shown to be specific for the TCR delta chain. In addition, the soluble TCR gamma delta-IgH heterodimer can be immunoprecipitated with the anti-clonotypic monoclonal antibody F10/56, which suggests that the fusion protein likely has a structural conformation similar to that of the native TCR. The COS cell expression system may prove useful for the production of additional TCR-IgH fusion proteins.

Animals↗
PubMed1992

IL-10 inhibits mitogen-induced T cell proliferation by selectively inhibiting macrophage costimulatory function.

IL-10, a newly designated cytokine primarily produced by the Th2 subset of CD4+ T lymphocytes and Ly-1+ B lymphocytes, has recently been hypothesized to inhibit cytokine production by Th1 T cell clones by blocking accessory cell- (AC) dependent costimulatory function. To evaluate the effect of IL-10 on Con A-induced proliferative responses of resting murine T cells, purified T cells were cultured with different types of AC. The addition of IL-10 produced a 70 to 90% inhibition of resting T lymphocyte proliferation when purified populations of macrophages were used as AC, but had no effect on the AC function of T-depleted spleen cells, activated B cells, dendritic cells, or L cells. The inhibitory effects of IL-10 were inversely related to the concentration of mitogen and could be reversed by the addition of the neutralizing anti-IL-10 mAb, SXC1. The inhibition of macrophage AC function was not related to the induction of a suppressor cytokine as stimulation by mixtures of macrophages and limiting numbers of dendritic cells was not inhibited. The decrease in proliferative responses was primarily secondary to inhibition of IL-2 production although the failure of exogenous IL-2 to completely reconstitute the response suggested that IL-10 may also exert inhibitory effects on the induction of expression of a functional IL-2R. These results are most consistent with a model in which IL-10 inhibits the induction of expression on macrophages of a critical costimulatory molecule that may be constitutively expressed on other types of AC.

Animals↗
PubMed1992

Gene transfer demonstrates that the V gamma 1.1C gamma 4V delta 6C delta T cell receptor is essential for autoreactivity.

Murine T cell lines and hybridomas derived from the epidermis that express the V gamma 1.1C gamma 4V delta 6C delta TCR and may, therefore, recognize an autoantigen, secrete cytokines spontaneously in culture. In addition, activation of these cells requires engagement of the vitronectin receptor (VNR) by extracellular matrix proteins. To further evaluate the role of the TCR, the VNR, and the putative autoantigen in the activation of this T cell subset, we cloned complete cDNA encoding the V gamma 1.1C gamma 4 and V delta 6C delta TCR and transfected the cDNA constructs into a TCR- murine hybridoma and into a TCR- variant of the human Jurkat line. The murine transfectant spontaneously produced IL-2 in culture and IL-2 production could be inhibited by anti-CD3, anticlonotypic mAb to the transfected TCR, and anti-VNR mAb, as well as by RGDS. These results demonstrate that transfection of the gamma delta TCR confers to recipient T cells the phenotype of constitutive activation, as well as dependence on engagement of the VNR as an accessory molecule. In contrast, the Jurkat gamma delta transfectant failed to produce cytokines spontaneously, although the transfected TCR was capable of signal transduction after stimulation by anti-TCR mAb. Surprisingly, neither the murine transfectant nor the human transfectant could be induced to respond to autoantigen bearing cells in coculture assays. One interpretation of these results is that coexpression on the surface of the same cell of the V gamma 1.1 V delta 6 TCR, the VNR, and a putative autoantigen are necessary for T cell activation in this system.

Animals↗
PubMed1992

Mouse autoreactive gamma/delta T cells. I. Functional properties of autoreactive T cell hybridomas.

A minor population of dendritic epidermal T cells (DETC) express the V gamma 1.1C gamma 4V delta 6 T cell receptor and T cell clones and hybridomas derived from this subset constitutively secrete cytokines in culture secondary to recognition of an autoantigen. Activation of these autoreactive cells requires the use of the vitronection receptor (VNR) as an accessory molecule which interacts with the Arg-Gly-Asp-Ser (RGDS) sequence of extracellular matrix (ECM) proteins. We have compared the functional properties of C gamma 4+ hybridomas derived from newborn thymocytes and from adult spleen with the DETC hybridomas/lines in terms of their ability to secrete cytokines spontaneously and for the use of the VNR as an accessory molecule. Almost all the C gamma 4+ thymocyte hybridomas secreted cytokines spontaneously and in the majority of lines the most prominent cytokine secreted was granulocyte-monocyte colony-stimulating factor. In contrast, none of the four splenic C gamma 4+ hybridomas secreted cytokines spontaneously although all were capable of cytokine production following activation via the T cell receptor. Although the thymocyte hybridomas did not grow as adherent cell lines in culture, constitutive cytokine production required engagement of the VNR by its ligand in ECM proteins. In all cases, cytokine production could be inhibited by an anti-VNR monoclonal antibody as well as by soluble RGDS. The strong correlation of functional and molecular properties between thymocyte C gamma 4+ hybridomas and C gamma 4+ DETC suggests that the C gamma 4+ DETC may be of thymic origin and that cells with potential for autoreactivity residing in the thymus at birth may populate other peripheral locations in the mouse. The data also support the concept that the VNR, and possibly other integrins, play a role as accessory elements for autoreactive cells and may be essential for the regulation of such activity.

Animals↗
PubMed1992

Mouse autoreactive gamma/delta T cells. II. Molecular characterization of the T cell receptor.

A panel of dendritic epidermal T cell (DETC) lines, and hybridomas derived from them, has been shown to spontaneously secrete lymphokines in the absence of added stimuli, which suggests that these cells are autoreactive. These cell lines are characterized by the expression of a V gamma 1.1C gamma 4/V delta 6 type T cell receptor (TcR), but several of the DETC lines also express a second TcR. Sequence analyses of these gamma/delta TcR revealed that the gamma chains were identical and that the delta chains, while not identical, were quite restricted in diversity, indicating that these receptors may recognize a common or closely related group of antigens. Analysis of hybridomas derived from newborn thymocytes identified six hybridomas that spontaneously secrete lymphokines. Five hybrids expressed a V gamma 1.1C gamma 4/V delta 6 receptor and one hybrid a V gamma 1.1C gamma 4/V delta 4 receptor that had a close structural relationship to the DETC gamma/delta TcR associated with spontaneous lymphokine secretion. gamma/delta TcR of the C gamma 4 type expressed by splenic hybridomas that did not spontaneously secrete lymphokines revealed no such relationship. Curiously, like the DETC, several of the thymocyte hybridomas that spontaneously secreted lymphokines expressed a second TcR, V gamma 2C gamma 1 or V gamma 3C gamma 1, apparently in association with the same delta chain that paired with the C gamma 4 chain. The presence of spontaneous lymphokine-secreting gamma/delta T cells with such highly homologous TcR in both the thymus and skin suggests a thymic origin for the autoreactive DETC and that these cells recognize a common or closely related group of self-antigens.

Amino Acid Sequence↗
PubMed1991

Immunoregulatory role of gamma delta T cells.

While the major population of T lymphocytes express T cell receptor (TCR) alpha beta-chains and recognize peptide antigens in association with either Major Histocompatibility Complex class I or class II molecules, a consensus view does not exist concerning either the nature of the antigen recognized or the nature of the restriction element utilized by the minor population of T cells which express TCR gamma delta-chains. We have identified a unique subpopulation of gamma delta T cells which uniformly express the C gamma 4, V delta 6 TCR and which produce a number of cytokines in the absence of exogenous stimulation. Adaption of these cell lines to serum-free culture conditions resulted in a cessation of cytokine production which could then be induced by the addition of extracellular matrix (ECM)-proteins to the culture. The response to the ECM-proteins could be completely inhibited by an antibody to the murine vitronectin receptor (VNR). However, engagement of the VNR by its ligand was not sufficient for the induction of cytokine production as anti-TCR antibodies inhibited the response to ECM-proteins and gamma delta TCR loss mutants failed to respond. Collectively, these data demonstrate that not only is coexpression of the VNR and the gamma delta TCR required for the induction of cytokine production by this subpopulation of T cells, but that the TCR must also be engaged by its ligand, most likely a cell surface autoantigen expressed by the T cells themselves.

Animals↗
PubMed1991

CD59 functions as a signal-transducing molecule for human T cell activation.

The CD59 Ag is a 20-kDa protein that is widely expressed on most leukocytes and RBC, is coupled to the membrane by a phosphatidylinositol-glycan anchoring structure, plays a role in cell interaction between monocytes and T cells, and also functions as an inhibitor of cytolysis by the terminal C components C5b-9. Because this molecule is structurally related to the murine Ly-6 family of Ag, we have investigated whether anti-CD59 mAb might be capable of activating human T lymphocytes in a manner similar to that described for antibodies to the murine Ly-6 Ag. In the presence of the appropriate co-stimulators, mAb to one of the two epitopes on CD59 were capable of inducing both a rise in intracytoplasmic free Ca2+, inositol phosphate production, IL-2 production, and T cell proliferation. Anti-CD59-induced inositol phosphate turnover and IL-2 production were dependent on co-expression of the CD3/TCR complex. CD59-loss mutants of the Jurkat cell line were completely responsive to stimulation by anti-CD3 thereby demonstrating that CD59 does not play a role as a signal transducer downstream from the TCR. Taken together, these results demonstrate that the CD59 Ag can play multiple distinct roles in the regulation of the immune response.

Antibodies, Monoclonal↗