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Biomedical subjects

S Dray

Publications and source records attributed to S Dray.

At least 73 records · Page 4Linked to original sources
PubMed1979

Heavy chain variable region allotypic subspecificities of rabbit immunoglobulins. II. Selective escape of the a1-AB Ig subpopulation after the induction of auto anti-a1 antibody.

An a1a2 rabbit (P286-3), neonatally suppressed for the expression of the a1 allotype, was immunized with autologous a1 IgG at 2 months of age. Both auto anti-a1 Ab and a1 IgG molecules were found in the serum of this rabbit after the auto-immunization. The auto anti-a1 Ab and the IgG from the auto anti-a1 Ab-depleted serum were isolated. Of the previously defined a1-AB, a1-AC, and a1-AD Ig subpopulations, the a1 IgG in the IgG preparation from the rabbit P286-3 were all of the a1-AB Ig subpopulation. The auto anti-a1 Ab from rabbit P286-3 did not react with the a1-A, a1-B, and a1-C allotypic subspecificities; thus, it was presumably specific for the a1-AC and a1-D allotypic subspecificity. Thus, the a1-AB Ig subpopulation escaped from allotype suppression in rabbit P286-3, whereas the a1-AD Ig subpopulation remained suppressed. The a1-AD Ig subpopulation will probably remain suppressed for a long time and perhaps permanently since rabbit P286-3 has produced circulating auto-Ab specific for the a1-D allotypic subspecificity. These results indicate that the a1 Ig subpopulations are synthesized by distinct clones of lymphocytes under separate control.

Aging↗
PubMed1979

Dependence of lymphocyte surface Ig on continuous polyclonal activation.

We have previously shown that most rabbit splenic B cells cultured in a medium supplemented with 5% autologous serum require continuous polyclonal stimulation to maintain detectable amounts of surface Ig. In the absence of this stimulation B cells shed but do not replace their surface Ig. Here, we investigated the mechanism responsible for the loss or maintenance of surface Ig. We showed that the addition of inhibitors of mRNA and protein synthesis to the cell cultures completely abolished the Ig maintenance effect provided by the mitogen thereby suggesting that it did not act by 'freezing' the membrane Ig but rather by continuously stimulating resynthesis. Moreover, by labelling the surface Ig with 125I-labelled Fab anti-allotype antibody we showed that the maintenance of surface Ig by mitogen stimulation was due to the turnover of surface Ig. The cells shed and replaced their surface Ig with a half-life of about 2 h only when mitogen was present but shed without replacing the surface Ig in the absence of mitogen. Also, the B-cell mitogens, SM and LPS, were able to maintain surface Ig even at extremely small concentrations while the T-cell mitogens, Con A and PHA, failed to do so at any concentration, suggesting that direct stimulation of B cells was needed to maintain surface Ig. When spleen cells were cultured in 'crowded' conditions in the absence of mitogen they did not lose their surface Ig; under these conditions it appeared that a factor associated with the macroglobulin fraction is induced and acts in the same manner as a B-cell polyclonal activator to maintain the turnover of surface Ig. Such a factor may actually function in vivo since lymphocytes are in very close contact in the lymphoid organs. We concluded that rabbit B lymphocytes shed and replace their surface Ig with a half-life of about 2 h and that the replacement, but not the shedding of surface Ig, is dependent on continuous exogenous or endogenous polyclonal activation.

Animals↗
PubMed1978

Identifying immunoglobulin isotypes, allotypes and idiotypes by a hemolytic assay in gel.

We developed a hemolytic radial immunodiffusion assay for identifying immunoglobulin (Ig) isotypes, allotypes and idiotypes by using gels containing erythrocytes coated with anti-Ig antibody or erythrocytes coated with Staphylococcal protein A. These indicator cells lysed specifically when treated sequentially with Ig antigen, the appropriate anti-Ig antiserum (developer) and complement. To identify these Ig subpopulations, we used monospecific indicator cells, e.g. erythrocytes coated with antibody specific for an Ig isotype, and developers with broader specificities ('multispecific'), e.g. antiserum to Fab. Alternatively, we used 'multispecific' indicator cells, e.g. erythrocytes coated with antibody to Fab and monospecific developers, e.g. antiserum to Ig idiotype. To identify Ig subpopulations specifically, either the indicator cells or the developer need to be monospecific. When both the indicator cells and the developer were monospecific, e.g. to allotype and to isotype, the specificity was determined by both reagents and ultimately restricted by the reagent with the narrower specificity, that is, reacting with the smallest Ig subpopulation. This sensitive hemolytic assay may be used to quantitate subpopulations of Ig molecules and may be modified into a reverse plaque forming cell assay to count lymphocytes secreting a given Ig class, type, allotype and idiotype.

Agar↗
PubMed1978

Antitumor immunity in strain 2 guinea pigs immunized with potassium chloride extracts of L2C tumor cells.

Extracts of L2C tumor cells stimulated in vitro production of macrophage migration inhibitory factor (MIF) in peritoneal exudate cells from guinea pigs immunized with L2C tumor cells. Guinea pigs immunized with extracts of L2C tumor cells that were active in vitro (in the MIF assay) were completely resistant to challenge with viable tumor cells given 2 weeks later. Furthermore, guinea pigs immunized with extracts of L2C tumor cells within 1 hour after challenge with viable L2C tumor cells survived substantially longer than did nonimmunized controls. The immunoprotective and immunotherapeutic effects seen in guinea pigs given injections of viable L2C tumor cells were obtained with extracts of L2C tumor cells but not with extracts of another guinea pig tumor (line 10 hepatoma) or with extracts of normal guinea pig lymphoid cells.

Animals↗
PubMed1978

Comparison of tumor-associated surface antigens on cells from medulloblastomas and from other neoplasms of the human nervous system.

We used a new immunocytoadhesion method to test 15 different tumors of the human nervous system to see whether medulloblastomas share tumor-associated surface antigens (TSA) with other tumors. Antisera against medulloblastoma cells were raised in rabbits. One antiserum was adsorbed extensively with tonsil and adenoid cells and with cerebral tissues. Freshly isolated cells from 15 different tumors were first sensitized with the adsorbed antiserum and then rosetted with erythrocytes coated with purified antibody to rabbit immunoglobulin. We found that the antimedulloblastoma antiserum detected TSA on the immunizing medulloblastoma cells and on cells from 2 other medulloblastomas, but apparently not on cells from other tumors (astrocytomas, glioblastomas, neurinoma, meningiomas and craniopharyngioma). In addition, the antiserum probably detected the medulloblastoma TSA on some other tumors (oligodendroglioma, ependymoma and malignant glioma of mixed type).

Adolescent↗
PubMed1978

Protection against MOPC-315 plasmacytoma by immunization with C-type particle preparations.

Mice were given injections of C-type particles extracted from the ascitic fluid of plasmacytoma-bearing mice. These particles, extracted from MOPC-315 tumor-bearing mice and injected into BALB/c mice, protected them against challenge with MOPC-315 tumor cells. The protection was dependent upon tumor cell dose; 66% survival was observed with a lethal dose of tumor cells. No protection was observed against challenge with another plasmacytoma (S13). Attempts to protect mice against S-13 plasmacytoma by immunizing them with C-type particles originating from S-13 tumor-bearing mice were unsuccessful.

Animals↗
PubMed1978

Longitudinal studies showing alterations in the levels and functional response of T and B lymphocytes in human pregnancy.

Altered blood levels of T and B lymphocytes were found in the first half of human pregnancy. A total of twenty-two women were tested, using direct or indirect rosetting assays or the fluorescence-activated cell sorter, to determine the levels of peripheral blood T and B cells. In all cases, an inversion of T- and B-cell levels was observed, i.e. T-cell levels were decreased and B-cell levels (as measured by the presence of surface immunoglobulin or the presence of B-cell surface antigens) were increased. This inversion was exhibited as early as 1 week post-implantation. Lymphocytes from two fo the women were also examined for stimulation with phytohaemagglutinin (PHA) and pokeweed mitogen (PWM) at intervals during gestation, and the amount of [3H]thymidine uptake was compared to that of two non-pregnant women tested at each interval. The values obtained for the pregnant women with PHA were markedly lower, and with pokeweed mitogen slightly lower, than those of non-pregnant controls. However, the PHA and PWM values in the pregnant women returned to levels similar to those of the nonpregnant women shortly after the T- and B-cell levels returned to normal. Thus the decrease in the response of the lymphocytes to mitogens during early pregnancy appears to parallel the numerical deficiency of T cells.

B-Lymphocytes↗
PubMed1978

Generation of anti-MOPC-315 cytotoxicity in uneducated or in vitro educated spleen cells from normal or MOPC-315 tumor-bearing mice pretreated in vivo with Bacillus Calmette-Guérin.

Cultured spleen cells from normal or MOPC-315 tumor-bearing BALB/c mice that were pretreated in vivo with Bacillus Calmette-Guérin (BCG) exhibited in vitro cytotoxicity against MOPC-315 plasmacytoma. In vitro education of BALB/c spleen cells from normal or tumor-bearing mice by cocultivation with mitomycin C-treated MOPC-315 stimulator cells also resulted in antitumor cytotoxicity. The combination of BCG pretreatment of donor mice with the in vitro education of their spleen cells resulted in a level of anti-MOPC-315 cytotoxicity that was greater than the sum of the levels of cytotoxicity exhibited by spleen cells subjected to either process alone. The levels of cytotoxicity exhibited by educated or uneducated spleen cells from BCG-pretreated mice were dependent on the dose of BCG used and on the time interval between in vivo pretreatment and the initiation of in vitro culture. Thus, our findings suggest that educated spleen cells from tumor-bearing hosts that were pretreated with BCG might be useful in immunotherapeutic regimens requiring histocompatible cells with augmented antitumor cytotoxicity.

Animals↗