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Biomedical subjects

S Dubiski

Publications and source records attributed to S Dubiski.

At least 55 records · Page 3Linked to original sources
PubMed1977

Allotype suppression in rabbits: the requirement for CH3 domain of anti-allotype antibody.

Facb fragments of rabbit anti-allotype antibody were prepared by plasmin digestion and isolated by gel chromatography. The antibody preparation was used in an attempt to induce allotype suppression in newborn rabbits. The Facb fragments were found to be ineffective in inducing the allotype suppression. Administration of Facb fragments caused a "burst" of immunoglobulin synthesis almost immediately after the administration of the antibody. It was concluded that the CH3 domain, which is responsible for the cytophilic activity of the antibody, is essential in induction of allotype suppression.

Animals↗
PubMed1976

Rabbit lymphoid cells. I. T-cell mitogens, cell volume and adherence properties as probes for cellular heterogeneity.

Thymus-derived cell populations were characterized by sedimentation velocity in the Earth's gravitational field, by adherence properties, and in terms of the thymus-specific antigen RTLA. T cells, responding to mitogens, could be shown to be a subpopulation of RTLA-bearing cells and to have a relatively large volume. The size distribution of mitogen-responsive cells from different individuals showed some variation, but in general large spleen cells took up less thymidine per 10(6) cells than did large cells from other lymphoid organs. Upon stimulation with concanavalin A (con A) small popliteal lymph node cells took up more thymidine per 10(6) cells than did small thymus cells. The corresponding small cells of mesenteric lymph node and spleen took up intermediate quantities of thymidine. Thymus-derived cells that were resistant to complement-mediated cell kill with RTLA antiserum showed greater responsiveness to con A than did the original cell preparations. Non-adherent cells incorporated more thymidine when stimulated with phytohaemagglutinin (PHA) than when they were stimulated with con A. Lightly adherent cells were relatively more responsive to con A stimulation and firmly adherent cells were less responsive to both. The findings were discussed in terms of the density of RTLA on the membranes of T cells. In adherence and in sedimentation velocity fractionation, the relative yield of nucleated cells always exceeded the yield of PHA- and con A-responsive cells. The differential separation of mitogen responsive and of co-operating cells were considered as a possible cause of this deficit.

Animals↗
PubMed1976

Rabbit lymphoid cells. II. Anti-allotype antisera, lipopolysaccharide and other bacterial and fungal mitogens as probes for the identification of B-cell subpopulations.

Removal of adherent cells or complement-mediated killing of rabbit thymus lymphocyte antigen (BTLA) bearing rabbit T lymphocytes did not abolish the responsiveness (increased thymidine incorporation) of lymphoid cells to antibody against immunoglobulin allotype, Nocardia water-soluble mitogen (NWSM), pneumococcal polysaccharide SIII (PPSIII), S. abortus lipopolysaccharide (LPS), lipid A conjugated to bovine serum albumin and a crude preparation containing C polysaccharide from the cell wall of Diplococcus pneumoniae. Isologous and heterologous antisera, directed against different portions of the Ig receptor, differed in their capacity to enhance thymidine incorporation. The difference in mitogenicity of these antisera was discussed in terms of the accessibility of cell-bound immunoglobulin receptor sites. Spleen cells, responsive to anti-allotype (Ab4) antiserum and B-cell mitogens, NWSM and PPSIII, were characterized by velocity sedimentation. The mean volume of NWSM- and PPSIII-responsive cells was larger than that of the cells responsive to anti-allotype antiserum. Fractionation of spleen cells on glass bead columns yielded a population of non-adherent cells which were two to six times as responsive to anti-Ab4 antiserum as the original spleen cell suspension. The responsiveness of peripheral blood lymphocytes to anti-Ab4 antiserum was significantly greater than that of spleen cells. On the other hand, spleen cells were more responsive to PPSIII than were cells from the peripheral blood, the popliteal and the mesenteric lymph nodes.

Animals↗
PubMed1975

Volume, adherence properties, membrane antigens and mitogen responsiveness of rabbit lymphoid cell subpopulations.

Subpopulations of rabbit spleen cells which respond to T and B mitogens, respectively, can be distinguished by sedimentation velocity in the earth's gravitational field. T cell subpopulations which differed in their responsiveness to Con A and to PHA could be identified by differences in adherence properties and by their sensitivity to complement mediated cell kill with RTLA-antiserum.

Absorption↗
PubMed1975

Blast transformation of rabbit B-derived lymphocytes by a mitogen extracted from Nocardia.

Nocardia water soluble mitogen (NWSM) is known to stimulate mouse and rabbit lymphoid cells and to act selectively on murine B-derived lymphocytes. In this paper, evidence is presented that NWSM is also a mitogen for rabbit bursal equivalent cells and does not bring about blast transformation of thymus-derived rabbit cells. Pretreatment of rabbit spleen lymphocytes with antibody directed against rabbit thymus lymphocyte antigen (anti RTLA serum) and with complement did not affect the strong increase of thymidine incorporation which follows stimulation with NWSM. The mitogen-induced polyclonal activation of antibody-forming cells and resulted in the presence of 30% of cells with the ultrastructural characteristics of plasmocytes. These observations led to the conclusion that NWSM is a mitogen for a B-derived lymphocyte of the rabbit.

Animals↗
PubMed1975

Maternal-foetal transfer of normal IgM in the rabbit.

Rabbits foetal sera harvested on the 28th day of gestation and sera from newborn rabbits were subjected to chromatography on Sephadex G-200. IgM and IgG were found in these sera. These immunoglobulins carried only maternal allotypic specificities and therefore, were not synthesized by the foetuses, but were transferred from the maternal circulation. The elution profile of the IgM found in the foetal sera and in sera from newborn rabbits indicated that this immunoglobulin was in its polymeric form. It was concluded that relatively high concentrations of polymeric IgM are transferred from mother to foetus.

Animals↗
PubMed1975

Allotypic suppression in rabbits: competition for target cell receptors between isologous and heterologous antibody and between native antibody and antibody fragments.

Neonatal injection with various foreign proteins (normal goat serum, human Cohn fraction II, human albumin) caused a stimulation of immunoglobulin synthesis. This effect was not antigen-specific and did not constitute a conventional antibody response directed against the injected substance. When this stimulatory effect of foreign protein was minimized, the heterologous (goat) anti-rabbit allotype antibody and rabbit antibody F(ab') 2 fragments not only failed to induce suppression but also competed with the suppression-inducing native rabbit antibody. Allotypic suppression in a rabbit can thus only be induced by an antibody molecule possessing an intact Fc portion of isologous, rabbit origin. Antibody to Ae14, an allotypic specificity located on the Fc portion, failed to induce suppression or stimulation of immunoglobulin synthesis. This was attributed to the position of Ae14 in the cell membrane which reduced its accessibility to antibody.

Albumins↗