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Biomedical subjects

M Schlesinger

Publications and source records attributed to M Schlesinger.

At least 253 records · Page 14Linked to original sources
PubMed1977

Association between HLA determinants and complement receptors on human lymphocytes.

The relationship between the major histocompatibility complex (MHC) and functional receptors on the surface of human lymphocytes was studied. HLA antisera were tested for their effect on the formation of E-, EA-, and EAC'-rosettes by human peripheral blood lymphocytes (PBL). Antisera to various HLA specificities inhibited the formation of EAC'-rosettes, but had no effect on the formation of E-rosettes. The formation of EA-rosettes was inhibited by HLA antisera only in part among the individuals tested. Anti beta2-microglobulin serum resembled HLA antisera in its effect on the formation of the various rosettes. HLA determinants and complement receptors are different entities on the cell surface since elimination of complement receptors by trypsin treatment does not seem to affect the expression of HLA antigens on the cell surface. It is suggested that EAC' receptors are located close to HLA determinants.

Binding Sites, Antibody↗
PubMed1977

Effect of thymic humoral factor on intracellular levels of cyclic AMP in human peripheral blood lymphocytes.

The exposure of human peripheral blood lymphocytes to thymus hormone causes an increase in the intracellular cyclic AMP level in these cells. Studies of the thymus-hormone-induced changes in cellular cyclic AMP levels revealed that cord blood lymphocytes contain significantly more target cells for the hormone than adult peripheral blood lymphocytes. The data obtained also suggest that the interaction between the hormone and its target cell is not readily reversible and that only a certain proportion of target cells in a given population of lymphocytes can be activated by a constant and limited amount of thymus humoral factor.

Adult↗
PubMed1977

The synthesis of transcobalamin II, a vitamin B12 transport protein, by stimulated mouse peritoneal macrophages.

The concentration of transcobalamin II (TCII), the vitamin B12 binding protein which delivers vitamin B12 to the tissues, was determined in stimulated and non stimulated mouse peritoneal exudate cells (PEC). Following a single intraperitoneal thioglycollate injection there was a marked increase in TCII which was shown to be produced by the adherent cells of the PEC i.e. the macrophages. It has been concluded that the PEC macrophages synthesize TCII.

Animals↗
PubMed1976

The effect of radiation therapy on lymphocyte subpopulations in cancer patients.

The proportion of T and B lymphocytes in the peripheral blood was determined in patients with either mammary cancer or with various pelvic malignancies. In cancer patients studied prior to irradiation the level of cells forming either E-rosettes or EAC'-rosettes was similar to that found among healthy controls. Radiation therapy resulted in a striking lymphopenia. The level of cells with T-cell markers was diminished to a greater extent than the level of cells with B-cell markers. The relative proportion of T-cells forming high affinity E-rosettes was not reduced following radiation, so that it can be concluded that radiation affects predominantly the subpopulation of T-cells which do not form high affinity E-rosettes. Irradiation of the pelvic area resulted in a more rapid reduction of the level of T lymphocytes than irradiation of the mediastinum, although the final relative proportions of the cells were similar in both groups of patients. The results of the present study suggest that the reduction of the level of T lymphocytes following irradiation results from its effect on the lymphocytes in the major blood vessels, and that radiation of the thymus is not a prerequisite for this phenomenon.

B-Lymphocytes↗
PubMed1976

Cell surface receptors and lymphocyte migration.

Lymphocyte subpopulations show a marked specificity in their distribution in various parts of the lymphoid system. It has been suggested that specific localization of lymphocytes depends on the presence of homing" receptors on their cell surface. The present paper summarizes some of the approaches used in the study of cell surface receptors involved in the migration and localization of lymphocytes. The effect of exposure of lymphocytes to antibodies, enzymes or lectins, on their capacity for localization is described. It is concluded that the experimental procedures employed do not provide conclusive evidence as to the mechanisms of lymphocyte localization, and that the role of homing receptors is still far from clear.

Animals↗
PubMed1976

Antigenic properties of subsets of splenic T lymphocytes responding to lectins.

The aim of the present study was to characterize the antigenic properties of spleen cells responding in vitro to various mitogenic stimuli. Mouse spleen cells were treated with alloantibodies and C and then cultured with various concentrations of lectins. The exposure of spleen cells to various dilutions of either anti-theta serum and C or anti-Ly serum and C inhibited the response to optimal concentrations of PHA to a greater extent than the response to optimal concentrations of Con A. With the exception of the optimal lectin concentration, theta-antiserum and C had a stronger inhibitory effect on the response to Con A than to PHA. The exposure of spleen cells to H-2 antiserum and C inhibited their response to Con A to a greater extent than to PHA. The inhibitory activity of H-2 antiserum and C was inversely correlated with the dose of PHA used for stimulation. The lower the concentration of PHA used for stimulation the more effective was the inhibitory effect of the antiserum. The inhibitory effect of H-2 antiserum and C on the response to Con A was highest at optimal concentrations of the mitogen, and somewhat less pronounced above or below this concentration. The present study suggests that subsets of splenic T-cells that react to various concentrations of mitogens, differ in their theta- and H-2 alloantigenicity.

Animals↗
PubMed1976

The formation of stable E-rosettes by human T lymphocytes activated in mixed lymphocyte reactions.

The aim of the present study was to determine whether activation of human T-lymphocytes affects their interaction with sheep red blood cells (SRBC). Less than 3% of the E-rosettes formed by freshly isolated peripheral blood lymphocytes (PBL) and SRBC are stable and do not disintegrate after incubation at 37 degrees C. In contrast, about 30% of PBL kept in culture for 5 days in the presence of mitomycin C-treated allogeneic lymphocytes were found to form stable E-rosettes. Whereas no rosettes were formed by freshly isolated PBL incubated with human red blood cells at 24 degrees C, 15% of the cells recovered from mixed lymphocyte reactions (MLR) formed such rosettes. When responder PBL were maintained in culture in the absence of allogeneic stimuli the proportion of cells forming stable E-rosettes depended on the serum present in the medium. Less than 5% of the responder cells kept in medium containing human serum or in serum-free medium formed stable E-rosettes, whereas 18% of the cells maintained in medium containing fetal calf serum formed stable E-rosettes. The proportion of cells forming stable E-rosettes increased before any increase in DNA synthesis was detectable in MLR. Indeed, a high proportion of cells forming stable E-rosettes appeared in MLR taking place in serum-free medium, without any accompanying increase of DNA synthesis. Depletion of cells forming EAC'-rosettes from responder PBL increased the proportion of cells forming stable E-rosettes in MLR. Exposure of the cells recovered in MLR to specific anti-T sera inhibited the formation of both stable and regular E-rosettes. Exposure of the cells recovered in MLR to anti-Ig serum had no effect on the formation of regular rosettes. Anti-Ig serum strongly inhibited the formation of stable E-rosettes by cells grown in medium containing human serum, but had no effect on the formation of stable E-rossettes by cells grown in either serum-free medium or in serum containing fetal calf serum. It is concluded that activated human T lymphocytes are characterized by their capacity to form stable E-rosettes, resistant to incubation at 37 degrees C, and by their capacity to acquire an immunoglobulin coat, possibly by binding immunoglobulin molecules present in their environment.

Animals↗
PubMed1976

Response of human lymphocytes to PHA and Con A, dependent on and regulated by THF, a thymic hormone.

The response of human lymphocytes to T lectins was shown to be dependent on and regulated by THF (thymus humoral factor). When human lymphocytes were stimulated with T lectins in the presence of dialyzed human plasma (DHP) which probably contains a low thymic hormone concentration, we observed a reduced response to PHA and Con A, compared to that observed in the presence of whole human plasma (WHP). This reduced reactivity to T lectins in the presence of DHP was restored by the addition of plasma dialyzates or THF. On the contrary, addition of THF to cultures in the presence of WHP caused a significant reduction in reactivity to T lectins, suggesting that enhancement or reduction of the response of human lymphocytes to T lectins by THF depends on the endogenous content of the thymic hormone in the plasma. From the present data it is suggested that the response of human cells to PHA behaves differently from that to Con A, as reflected in their dependence on THF. Although the response of human cells to Con A is increased by THF only in the presence of DHP, the response to PHA is also enhanced by THF in the presence of low WHP concentrations of even in the absence of WHP.

Concanavalin A↗
PubMed1975

The nature and function of T-cell antigens.

T-lymphocytes differ antigenically from B-lymphocytes. In the present study attempts were made to determine the role of surface antigens of T-cells, in their migration in vivo and in their response to mitogens. Exposure of thymus cells to anti-H2 sera inhibits migration to the lymph nodes (LN) to a greater extent than to the spleen. Fab fragments of H-2 antisera had only a slight effect on lymphocyte migration, inhibiting the LN-seeking stream only slightly more than the spleen-seeking stream. The interaction of Con-A with carbohydrates on the cell-surface of lymphocytes inhibits preferentially their localization in LN. Studies on the migration of lymphocytes that had localized either in the LN or spleens of primary host indicate that Con-A does not eliminate LN-seeking cells, but rather inhibits their active localization in LN. The subpopulation of lymphocytes, in both thymus and spleen that responds to Con-A was found to possess a higher H-2 antigenicity and a lower Ly and theta-antigenicity than the cells responding to PHA. Spleen cells responding to low concentrations of PHA had a relatively high H-2 antigenicity, whereas thos responding to high concentrations of PHA had a low H-2 antigenicity. Exposure of thymus cells to H-2 antiserum alone markedly inhibited their response to Con-A. Similar treatment of spleen cells had only a weak inhibitory effect.

Animals↗