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E M Shevach

Publications and source records attributed to E M Shevach.

At least 253 records · Page 14Linked to original sources
PubMed1975

In vitro selection and extended culture of antigen-specific T lymphocytes. II. Mechanisms of selection.

Functional selection of antigen-specific T lymphocytes can be achieved by culturing thymus-dependent (T) lymphocytes from immunized guinea pigs on "monolayers" of antigen-pulsed adherent peritoneal exudate cells (PEC) from nonimmune syngeneic donors. Several aspects of the in vitro selection of T lymphocyte-rich peritoneal exudate lymphocytes (PEL) were studied. It was shown that irradiated adherent PEC were equivalent to nonirradiated adherent PEC in supporting selection cultures, indicating that the lymphocytes harvested at the end of the selection culture derive from the immune donors of the PEL and not from the nonimmune donor of the adherent PEC. The relative importance of specific adherence and specific proliferation for achieving selection was determined by comparing the degree of selection obtained when nonadherent cells were discarded at 24 hr with that noted when the discard step was omitted. It was found that omitting the discard step markedly diminished the degree of selection. On the other hand, blocking proliferation with specific alloantisera after the discard step did not diminish the degree of selection, although it did diminish the cell yield. Thus, specific adherence to antigen-pulsed PEC appeared to be critical in the selection culture procedure. An estimate of the degree of enrichment obtained by the selection culture procedure was obtained by culturing selected cells in an excess of nonprimed PEL, so that auxiliary cells would not be limiting. Under these conditions, it appeared that selected cells were enrichied from 4- to 10-fold in antigen-responsive cells with respect to the initial cell population.

Animals↗
PubMed1974

Alloantiserum-induced inhibition of immune response gene product function. I. Cellular distribution of target antigens.

It has been previously shown that alloantisera prepared by reciprocal immunization of strain 2 and strain 13 guinea pigs specifically block the activation of T lymphocytes from immune guinea pigs by antigens, the response to which is controlled by Ir genes. In this report we have examined the effect of absorption of the 13 anti-2 serum with different populations of lymphoid cells. It is unlikely that the inhibitory activity of the anti-2 serum on the proliferation of (2 x 13)F(1) lymphocytes to a DNP derivative of a copolymer of L-glutamic and L-lysine (DNP-GL) is due to the presence of antibodies specific for the unique antigenic determinants (idiotypes) of clonally distributed T-lymphocyte receptors. Thus, cells obtained from a normal animal and a DNP-GL immune animal were equivalent in their absorptive capacity. Populations of T lymphocytes were ineffective in absorbing either the cytotoxic or inhibitory activity of the anti-2 serum, while L(2)C leukemia cells, a malignant B-cell population, were most efficient in absorbing both activities. Thus, the antigen(s) against which the cytotoxic and inhibitory activities are directed are present to a greater extent on B lymphocytes than on T lymphocytes. However, these results do not allow us to definitively determine whether the inhibitory activity of the alloantisera is due to antibodies specific for Ir gene products or antibodies specific for linked antigens in the MHC. We also examined the effect of a number of anti-immunoglobulin reagents which had specificity for the heavy and/or light chains of guinea pig immunoglobulin on the in vitro lymphocyte proliferative response to antigen. Under conditions in which we were able to completely and specifically suppress the response of (2 x 13)F(1) lymphocytes to DNP-GL with anti-2 serum, the anti-immunoglobulin reagents were devoid of inhibitory effect on the response of these same F(1) cells to DNP-GL, a copolymer of L-glutamic and L-tyrosine (GT), or purified protein derivative of tuberculin (PPD). These results strongly suggest that conventional serum-type immunoglobulin is not important in antigen recognition by the T cells involved in the DNA synthetic response.

Absorption↗
PubMed1974

Alloantiserum-induced inhibition of immune response gene product function. II. Genetic analysis of target antigens.

It has been previously demonstrated that alloantisera can specifically block the activation of T lymphocytes by antigens, the response to which is linked to the presence of histocompatibility (H) types against which the alloantisera are directed. Thus, strain 13 anti-2 serum can inhibit the activation of (2 x 13)F(1) T lymphocytes by a DNP derivative of a copolymer of L-glutamic acid and L-lysine (DNP-GL), an antigen the response to which is controlled by a 2-linked Ir gene. It was proposed that alloantisera can inhibit T-lymphocyte antigen recognition through interference with the activity of immune response (Ir) gene products. In order to further study whether the inhibitory antibodies within the alloantisera are directed against H antigens or against the products of the Ir genes, we have examined whether the anti-2 serum can inhibit the function of an Ir gene (the L-glutamic acid and L-alanine [GA] gene), which is normally linked to strain 2 H genes when this gene occurs in an outbred animal lacking strain 2 H genes. In the majority of cases, the anti-2 serum was capable of inhibiting the in vitro proliferative response to GA of T cells derived from animals that were GA(+)2(+), but the serum had little if any effect on the GA response of T cells from GA(+)2(-) animals. Furthermore, an antiserum prepared in strain 13 animals against the lymphoid cells of a GA(+)2(-) outbred animal was devoid of inhibitory activity on the GA response of cells from a (2 x 13)F(1), while an antiserum prepared in strain 13 animals against the lymphoid cells of a GA(+)2(+) outbred animal was capable of specifically inhibiting the response to GA. It thus appears that the inhibition of the GA response by the anti-2 serum is primarily mediated via antibodies directed toward strain 2 H antigens rather than antibodies specific for the product of the GA Ir gene. The mechanism of alloantiserum induced suppression of Ir gene function would then be by steric interference with the Ir gene product on the cell surface, rather than by direct binding to it. This conclusion implies that the products of both the H genes and the Ir genes are physically related on the cell surface. The implications of such a relationship in terms of the fluid-mosaic model of the lymphocyte surface are discussed.

Antibody Formation↗
PubMed1973

Function of macrophages in antigen recognition by guinea pig T lymphocytes. I. Requirement for histocompatible macrophages and lymphocytes.

Antigen activation of DNA synthesis in immune thymus-derived lymphocytes of guinea pigs requires the cooperation of macrophages and lymphocytes. We have investigated the role of histocompatibility determinants in this macrophage-lymphocyte interaction using cells from inbred strain 2 and 13 guinea pigs. The data demonstrate that efficient presentation of macrophage-associated antigen to the lymphocyte requires identity between macrophage and lymphocyte at some portion of the major histocompatibility complex. The failure of allogeneic macrophages to effectively initiate immune lymphocyte proliferation was not the result of the presence of an inhibitor of blastogenesis released in mixtures of allogeneic cells, peculiarities of the antigen or lymphoid cells employed, nor differing kinetics of activation by allogeneic macrophages. In addition, data were presented that demonstrated that alloantisera inhibit lymphocyte DNA synthesis by functional interference with macrophage-lymphocyte interaction.

Animals↗
PubMed1973

Function of macrophages in antigen recognition by guinea pig T lymphocytes. II. Role of the macrophage in the regulation of genetic control of the immune response.

A number of recent studies have suggested that the main functional role of the product of the immune response (Ir) genes is in the process of antigen recognition by the T lymphocyte. The observation in the accompanying report that the interaction of macrophage-associated antigen with immune T lymphocytes requires that both cells share histocompatibility antigens raised the question as to whether the macrophage played a role in the genetic control of the immune response or even if the macrophage were the primary cell in which the product of the Ir gene is expressed. In the current study, parental macrophages were pulsed with an antigen, the response to which is controlled by an Ir gene lacking in that parent; these macrophages were then mixed with T cells derived from the (nonresponder x responder)F(1) and the resultant stimulation was measured. No stimulation was seen when column-purified F(1) lymph node lymphocytes were mixed with antigen-pulsed macrophages from the nonresponder parent. However, when the highly reactive peritoneal exudate lymphocyte population was used as the indicator cells, parental macrophages pulsed with an antigen whose Ir gene they lacked were capable of initiating F(1) T-cell proliferation. The magnitude of stimulation was approximately 1/10 that seen when macrophages from either the responder parent or the F(1) were used. In order to explain this observation, we hypothesize that antigen recognition sites on the T lymphocyte are physically related to a macrophage-binding site and both are linked to the serologically determined histocompatibility antigens. Thus, parental macrophages pulsed with an antigen, whose Ir gene they lack, activate F(1) cells poorly because the recognition sites for the antigen are physically related to the macrophage-binding site of the responder parent while the main contacts between the cells are at the nonresponder binding sites. Experiments performed with alloantisera lend support to this hypothesis. Thus, when parental macrophages are pulsed with any antigen and added to F(1) T cells, an alloantiserum directed against parental histocompatibility antigens reacts with both the lymphocyte and the macrophage and thereby inhibits macrophage-lymphocyte interaction and abolishes antigen-induced lymphocyte transformation. When the alloantisera are directed at determinants present solely on the T lymphocyte, they only inhibit the recognition of antigens controlled by the Ir gene linked to the histocompatibility antigen against which they are directed. We conclude from these studies that antigen recognition by the T lymphocyte is a complex multicellular event involving more than simple antigen binding to a specific lymphocyte receptor.

Animals↗
PubMed1972

Histocompatibility-linked immune response gene function in guinea pigs. Specific inhibition of antigen-induced lymphocyte proliferation by alloantisera.

A number of autosomal dominant immune response (IR) genes have been identified in both mice and guinea pigs. These IR genes have been shown to be linked to the major histocompatibility antigens of the species and to be functionally expressed primarily in T lymphocytes. In order to more fully understand the relationship between IR genes, histocompatibility antigens, and immune recognition, the effect of specific alloantisera on lymphocyte stimulation induced by antigens under control of IR genes was examined. Using lymphocytes from strain 2 or strain 13 animals, the in vitro proliferative responses both to antigens which are known to be under genetic control (DNP-GL in strain 2 guinea pigs and GT in strain 13 guinea pigs) and to an antigen which is not known to be under genetic control (PPD) were inhibited to a similar degree and to a much greater extent than the response to phytohemagglutinin. However, when cells from F(1) (2 x 13) animals are used, the alloantisera markedly inhibit only the response which is linked to the histocompatibility antigens against which the serum is directed. Thus, the anti-2 serum inhibited the response to DNP-GL but not to GT; the anti-13 serum inhibited the response to GT but did not affect DNP-GL response. The inhibitory activity of the alloantisera could not be removed by absorption with gamma globulin of the opposite strain. It can be concluded from these observations that immune response genes produce a cell surface-associated product and that this product plays a role in the mechanism of antigen recognition by the T lymphocyte. The mechanisms by which alloantisera block this process of antigenic recognition is not resolved nor is the relationship between the IR gene product and the antigen-binding receptor of the T lymphocyte. The approach described here offers a powerful tool for the resolution of these problems.

Animals↗
PubMed1972

Receptors for complement and immunoglobulin on human leukemic cells and human lymphoblastoid cell lines.

The bone marrow-derived (B) lymphocyte can be identified by the presence of easily detectable surface immunoglobulin and a receptor for antigen-antibody-complement complexes (EAC'). Monocytes and macrophages also bear a receptor for EAC' and in addition possess a receptor for red cell-IgG complexes (EA). Thymus-derived (T) lymphocytes bear neither of these receptors. The cells of 15 patients with leukemia and 19 human lymphoblastoid cell lines were examined for the presence of the EAC' and EA receptors. Of the human leukemias studied, only the cells from the patients with chronic lymphatic leukemia (CLL) possess the EAC' receptor. The EA receptor could not be demonstrated on CLL cells; hence, CLL cells bear the lymphocyte EAC' receptor and by this criteria represent B lymphocytes. 12/19 of the cell lines studied could be classified as B lymphocytes by the presence of the EAC' receptor and absence of the EA receptor. 2/19 cell lines possessed both the EAC' and EA receptors and thus resemble the monocyte. 5/19 cell lines had no detectable receptor for EAC' or EA. The approach presented in this study for the classification of leukemias and cell lines as to their B lymphocyte, T lymphocyte, or monocyte origin may have useful diagnostic and therapeutic implications.

Animals↗