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Biomedical subjects

S Dubiski

Publications and source records attributed to S Dubiski.

At least 37 records · Page 2Linked to original sources
PubMed1982

Mitotic response of rabbit peripheral blood lymphocytes to a factor in normal rabbit serum: a possible genetic polymorphism.

Normal rabbit sera contain a mitogen capable of stimulating rabbit peripheral blood lymphocytes in in vivo culture to incorporate radioactive thymidine. Cells from spleen, appendix or peritoneal exudate did not respond when cultured under similar conditions. The responding peripheral blood lymphocytes are adherent cells, but not macrophages. Presence of responding peripheral blood lymphocytes is a dominant trait. The response is regulated by a nonadherent, radiation-sensitive suppressor cell and by a nonadherent, relatively radiation-resistant helper cell.

Animals↗
PubMed1981

Relative expression of light-chain allotypic specificities on the surface of rabbit lymphocytes as a function of age.

Lymphoid cells of heterozygous Ab4/Ab9 rabbits of various ages were stained with fluorescent anti-allotype antibodies. In foetal and newborn rabbits, the percentage of Ab-positive cells in low; it increases with age, reaching the adult value when the animals are 100 days old. The rate of increase in the percentage of Ab4-positive cells is higher than in that of Ab9-positive cells. Thus, the Ab4/Ab9 ratio, which is initially 1, increases with age and reaches 2.2. in spleen and 4 in appendix of young adult animals. We conclude that the change in Ab4/Ab9 ratio is due to differential clonal expansion which we attribute to charge-related differences in the ability of Ab4 and Ab9 receptor-bearing cells to capture antigen when environmental antigens are encountered in postnatal life.

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PubMed1980

The effect of temperature-dependent autorosettes on B/T cell ratios of purified rabbit peripheral blood lymphocytes.

Contradictory reports as to B/T cell ratios in the peripheral blood lymphocytes (PBL) of rabbits led to an investigation of current purification methods. PBL prepared by sedimentation at 37 degrees C in gelatin solution showed the same B/T ratios as did whole blood. PBL prepared by the Ficoll-Hypaque method at 4 degrees C or at room temperature were enriched in B cells compared to the whole blood. This enrichment depended on the presence of autologous erythrocytes during centrifugation and it was not demonstrable when centrifugation was carried out at 37 degrees C. Resuspended red cell pellets contained more than 3 times as many rosette-forming cells if the pellets were obtained by centrifugation of blood on Ficoll at 4 degrees C rather than 37 degrees C. We, therefore, conclude that aggregation of T cells with autologous erythrocytes is responsible for the depletion of B cells in the PBL prepared by the Ficoll-Hypaque method at 4 degrees C or at room temperature.

Animals↗
PubMed1980

Isolation and characterization of a mouse-rabbit hybridoma.

Immunoglobulin was obtained from a hybridoma cell line, which was a reclone of a hybrid between a rabbit cell and mouse myeloma cell (X63-Ag8). The immunoglobulin, isolated from the cell culture medium was found to be homogeneous by isoelectrofocusing and immunoelectrophoresis and consisted of mouse heavy and rabbit light chains, linked by disulphide bonds. All immunoglobulin molecules carried both mouse and rabbit determinants; mouse determinants were associated only with the heavy chains while rabbit determinants were only associated with the light chains. The rabbit light chains were of Ab4 allotypical specificity, but possess only some of the Ab4 determinants normally present in Ab4/Ab4 animals. It was suggested that the restriction in allotypical specificity may be a general property of light chain Ab allotypes; the normal serum immunoglobulins may be heterogeneous with respect to the allotypic determinants and any one molecule may possess only a proportion of determinants detected by a conventional anti-allotype antiserum.

Animals↗
PubMed1980

Surface immunoglobulin receptors of rabbit lymphoid cells. Evaluation of fluorescent staining with antibodies to immunoglobulin light chain allotypes.

Rabbit lymphoid cells were stained with fluorescein-labelled antiallotype antibodies. The double layer technique was found to be more sensitive than the direct staining. Rabbit B cells are stained only via their surface immunoglobulin (sIg) receptors and not via the receptors for the Fc portion of the IgG. Peritoneal exudate macrophages do not carry sIg receptors and are stained via their Fc receptors. Removal of protein aggregates from the system and use of reagents prepared from F(ab')2 immunoglobulin fragments prevent staining of the macrophages through their Fc receptors. There was a good agreement between the percent of RABELA-positive and sIg-containing spleen cells. In appendix there were approximately 20% more RABELA-positive than sIg-positive cells.

Animals↗
PubMed1980

Proportions of T- and B-lymphocytes in preauricular lymph nodes and aqueous humour of rabbits showing corneal graft reactions.

We wished to determine the proportions of T- and B-lymphocytes in the preauricular lymph nodes and the anterior chambers of rabbits during various stages of graft reactions. The animals received unilateral orthotopic corneal xenografts or skin allografts on the ear. The target cells were identified with the use of fluorescein-tagged antisera specific for rabbit T- and B-lymphocytes. As compared with the percentage in the rabbits that had not received a graft, in both the xenograft and the allograft recipients the percentage of T-lymphocytes in the preauricular lymph nodes during the graft reaction did not change on the side that received the graft but was higher on the side that did not receive a graft. In the recipients of the corneal grafts, as the severity of the graft reaction increased, the percentage of B-lymphocytes in the preauricular lymph nodes on the side that received the graft and the percentage of T-lymphocytes in the lymphoid cell population infiltrating the anterior chamber of the grafted eye increased. The possible mechanisms underlying these phenomena are discussed.

Animals↗
PubMed1980

Basilea rabbit immunoglobulins: detection and characterization by specific alloantiserum.

Evidence is provided for the existence of the Fbbas (Basilea) gene product (allotype). Specific antisera were raised by immunization of rabbits that did not possess the Basilea genes. With the help of these antisera, the Basilea allotype was detected in sera from rabbits, homozygous and heterozygous with respect to Basilea gene. The Basilea gene is expressed on a very low proportion of immunoglobulin molecules. The isoelectric point of the Basilea light chains is distinct from that of the lambda-light chains (peaks at pH 4.7 and 5.5, respectively). Sera from a large proportion of Ab9-positive rabbits of the Basel Institute for Immunology that were heterozygous at the Ab locus reacted with the anti-Basilea serum, even though they could no possess the Basilea gene at the Ab locus. Sera from Ab9-positive rabbits from Toronto were Basilea-negative. It was suggested that Ab9 and Basilea allotypes are controlled at closely linked loci. Ab9 haplotype prevalent in the Basel animal colony, possesses both Ab9 and Basilea genes, whereas the corresponding Toronto haplotype has only the Ab9, but not Basilea gene. The formation of the Basilea genotype was attributed to a crossing over, during which the Ab9 and Basilea genes separated.

Animals↗
PubMed1979

Purification of rabbit B spleen cells by removal of adherent and of T cells.

B lymphocytes from the rabbit spleen were freed of T cells by removal of cells which formed rosettes with papain-treated rabbit erythrocytes. Additional purification could be achieved if fractionation by rosette removal was preceded by removal with a magnet of cells which adhered to or ingested poly L-lysine coated iron core particles. Cell yield and purification were assessed by complement mediated cytotoxic kill of B and T cells with antibody directed against RABELA and RTLA, respectively. Other criteria depended on determination of the number of Fc receptor bearing cells and of thymidine uptake by cells which were stimulated with concanavalin A, PHA or with antibody directed against the allotypic specificity of receptor Ig light chains. Purified preparations of B cells were obtained in a yield of about 20% of the B cells in the original spleen and contained less than 10% of cells which were not B cells. This method allows purification which does not interfere with the membrane of the isolated cells.

Animals↗
PubMed1979

Regulatory influences on the response of rabbit T cells to concanavalin A and phytohaemagglutinin.

The proliferative response, induced in rabbit spleen cells by concanavalin A (Con A) and phytohaemagglutinin (PHA), is abolished when T cells are killed with antibody against rabbit thymus lymphocyte antigen (RTLA) in the presence of complement. The response was examined with purified spleen T cells, to which various helper cell fractions were added; it could be shown that B cells help the responding T cells. The helper effect in the response to PHA is abolished and the response to Con A is reduced by any manoeuvre which destroys or removes B cells. Help by B cells is given when helper cells have lost proliferative capacity as a consequence of mitomycin-C treatment. Spleen cells adhering to the walls of culture tubes help suspended T spleen cells in their response to Con A. This help could be abolished by complement mediated cell kill with antibody to rabbit bursal equivalent lymphocyte antigen (RABELA). On the other hand, the helper effect in Con A response was increased when T cells were removed. Thus the response of T cells to Con A is regulated by helper B cells and suppressor T cells.

Animals↗
PubMed1979

A suppressor cell in the response of rabbit T cells to Con A.

The response to Concanavalin A is regulated by a helper cell, described elsewhere (4), and by a suppressor cell, described in this paper. This suppressor cell is an adherent T cell with Fc receptors. Evidence for properties of the suppressor cell was obtained by two types of experiments: 1) regulatory cells gave more help if Fc-bearing subpopulations were removed from them, i.e. the suppressor cell could not be removed with Degalan beads, coated with anti-allotype antibody, but not with beads, coated with F(ab')2 fragments of the antibody; 2) help for T cells, in their response to Con A, was augmented when T cells were eliminated from the regulating adherent cell preparation. Thus, the response of spleen T cells to Con A is regulated by two adherent cells, a B helper cell and a T suppressor cell. We have previously shown that the response to phytohemagglutinin (PHA) is regulated by an adherent helper cell (4). We have found no evidence, in the present study for an adherent suppressor cell which participates in the T cell response to PHA.

Animals↗
PubMed1979

Rabbit B spleen lymphocytes and T helper cells. I. Responsiveness to mitogens of B cell subpopulations of different sedimentation velocities and subpopulations bearing or lacking Fcgamma receptors.

The response to anti-allotype (anti-Ab4), Nocardia Water Soluble Mitogen (NWSM), pneumococcal polysaccharide type III (SSS III), and human Fc fragments of various purified and unfractionated rabbit spleen cell populations was determined in terms of 3H-thymidine up-take. B cells were isolated either from untreated suspensions of spleen cells or from suspensions from which adherent and phagocytic cells were removed. The purification factor was greater than the enhancement of 3H-thymidine uptake by anti-Ab4, NWSM, and SSS III as compared with the response of unfractionated spleen cells. It thus appears that a helper cell was involved: the mitogen response of purified B cells was enhanced by the addition of T cells. B subpopulations were separated by sedimentation or by rosetting, which allowed us to separate Fcgamma receptor-bearing cells from cells that did not possess this receptor. There were differences between cells responding to B mitogens not only in sedimentation velocity but also in the absolute number of cells. B cells bearing the Fcgamma receptor were less responsive to anti-Ab4 and more responsive to SSS III, NWSM, and human Fc than were B cells lacking the Fcgamma receptor.

Animals↗
PubMed1978

Effect of cyclic nucleotides, isoproterenol and cholera toxin on DNA synthesis triggered by mitogens.

The effect of cyclic nucleotides, isoproterenol and cholera toxin on phytohaemagglutinin (PHA), concanavalin A (Con A) and anti-allotype-induced rabbit lymphoid cell proliferation was examined. Cholera toxin in concentrations ranging from 10(-8) microgram to 1 microgram per culture inhibited DNA synthesis, triggered by PHA, Con A and nocardia water-soluble mitogen (NWSM). It had the opposite effect on stimulation with antibodies directed against allotypic specificities of the immunoglobulin light chains: over the entire range of tested concentrations, cholera toxin stimulated DNA synthesis triggered by antibodies to Ab4, Ab5, Ab9 and to Aa1 allotypic specificities. Relatively high concentrations of dibutyryl adenosine 3':5'-cyclic monophosphate (cAMP) and isoproterenol (10(-3) M) inhibited mitogen-stimulated thymidine incorporation; lower concentrations (10(-9) M) had an enhancing effect. A similar enhancing effect was observed when high (10(-3) M) concentrations of dibutyryl guanosine 3':5'-cyclic monophosphate (cGMP) were used.

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