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Biomedical subjects

R R Rich

Publications and source records attributed to R R Rich.

At least 19 recordsLinked to original sources
PubMed1992

Isolation and characterization of a novel streptococcal superantigen.

The involvement of S. pyogenes (group A Streptococcus) in severe invasive disease, toxic-shock-like syndrome, and episodes of rheumatic fever led us to explore the possibility that these strains produce a novel superantigen. By using a superantigen-specific assay, we purified a 28-kDa protein from culture supernatants that stimulated T cells in an MHC class II-dependent, V beta-specific manner and designated it SSA, streptococcal superantigen. The amino terminus of SSA showed striking resemblance to SEB, SEC1, and SEC3. The structural homology exhibited by SSA to SEB was reflected functionally in that both of these superantigens bound the same class II isotypes. In contrast, SSA differed from SEB and other known bacterial superantigens with respect to its pattern of V beta-specific T-cell activation. SSA stimulated human T cells that expressed V beta 1, 3, 15, and perhaps V beta 5.2. Using SSA-specific antibodies in an immunoblot assay, we screened 26 strains of Lancefield group A Streptococcus and 16 strains of group B, C, and G Streptococcus. We found that SSA was expressed with high frequency in group A strains, but was absent from all other groups tested. These data establish SSA as a novel superantigen secreted by S. pyogenes. Further study of the structure and expression of SSA may reveal a role for this molecule in current episodes of severe streptococcal diseases.

Antibodies, Bacterial↗
PubMed1979

Primary in vitro cytotoxic response of NZB spleen cells to Qa-1b-associated antigenic determinants.

We have shown that cytotoxic lymphocytes generated in primary cultures of NZB spleen cells with H-2-identical BALB/c or B10.D2 stimulator cells exhibit specificity for Qa-1b-associated antigenic determinants. This unidirectional cytotoxicity constitutes the initial demonstration of a primary in vitro response to antigens of the Qa-Tla system. Such responses do not require H-2 homology between effector and target cells in the assay system. In fact, when H-2Dd homologous target cells were employed there was little, if any, evidence for development of primary H-2-restricted responses to minor locus histocompatibility antigens or viral antigens. In view of the recently defined role of Qa-1+, Ly-1,2,3+ cells as regulators of antibody responses, and of the deficiency of such cells in NZB mice, the observation of hyperreactivity for determinants of this system may be relevant to the development of autoimmunity in these animals.

Animals↗
PubMed1979

Regulatory mechanisms in cell-mediated immune responses. VII. Presence of I-C subregion determinants on mixed leukocyte reaction suppressor factor.

The presence of H-2 gene products on mixed leukocyte reaction (MLR) supressor factor was investigated by passage of MLR-suppressor factor (SF) over solid immunoadsorbents prepared with various anti-H-2 subregion sera. Antisera with specificity for all or certain I subregion determinants removed or significantly reduced suppressor activity; adsorption was not consistent with K or D region specificity. The single I subregion specificity common to all adsorbing preparations was I-C. Serologic differentiation of I-C products of k and d haplotypes expressed on MLR-SF was established with antisera prepared in I-Cd/I-Ck disparate strain combinations. These sera define allelic T cell restricted Lad determinants encoded by I-C genes. MLR-SF prepared from (BALB/c X CBA)F1 mice and exposed to the I-Cd and I-Ck specific adsorbents demonstrated d and k haplotype specific adsorption respectively. F1 suppressor activity adsorbed on an anti-I-Cd column was eluted by glycine-HCl buffer and suppressed only BALB/c (H-2d) responses. B10.A suppressor activity was removed by anti-I-Cd sera, but was unaffected by anti-I-Ck sera, indicating that B10.A suppressor activity is encoded by an I-C subregion derived from the d haplotype. Antisera with anti-I-Jk specificity did not remove suppressor activity of various H-2k factors. Finally, adsorption with antisera directed against H-2-associated determinants of the allogeneic cell used to stimulate suppressor factor generation demonstrated that sensitizing alloantigens are not components of MLR suppressor factor. Thus among the major histocompatibility complex (MHC)-controlled suppressor factors, MLR suppressor factor is uniquely determined by the I-C subregion.

Animals↗
PubMed1979

Prenatal diagnosis of congenital adrenal hyperplasia.

The accurate prenatal diagnosis of 21-beta-hydroxylase deficiency, based on amniotic fluid levels of 17-hydroxyprogesterone, is documented for a fetus 14 1/2 weeks old. In addition, family HLA genotyping data are consistent with the purported linkage between the HLA locus and the locus for 21-beta-hydroxylase.

Adrenal Hyperplasia, Congenital↗
PubMed1979

Recognition of hapten-modified cells in vitro by human T-lymphocytes.

Clearer definition of the recognitive structures of human T lymphocytes for antigens will be required to elucidate the molecular basis of diseases and immunological responses induced or regulated by normal or abnormal T-cell function. For this purpose we have investigated the cellular requirements for immune responses in vitro to trinitrophenyl-conjugated peripheral blood mononuclear cells. The responding cell was characterized as a T cell on the basis of rosetting with sheep erythrocytes. T-cell recognition of hapten in proliferative responses depended upon presentation of antigen in an appropriate stimulator-cell context. Neither autologous hapten-modified erythrocytes nor T cells restimulated responses of in vitro-primed lymphocytes. Moreover, hapten-conjugated non-T cells were more effective than modified unfractionated cells in restimulating proliferative responses. Both macrophages and non-T lymphocytes effectively restimulated hapten-conjugate responses.Cell-mixing experiments indicated that the failure of haptenated T cells to stimulate proliferative responses was not because of a lack of fresh macrophages; these experiments suggested instead that T cells do not express appropriate structures necessary to present haptenic determinants in an immunogenic form. Hapten-modified T cells, however, were capable of inducing primed lymphocytes to become efficient cytotoxic effector cells, indicating that T-cell recognitive units for stimulation of proliferative and cytotoxic responses are different. These data support the concept that for induction of proliferative responses, human T cells recognize conventional antigens in association with HLA-D-region-encoded Ia-like molecules.

Antibody Formation↗
PubMed1979

Physiology of mixed leukocyte reaction suppressor factor. I. Role of cytoskeleton and protein synthesis in production and secretion.

The secretory physiology of the T cell-produced lymphokine, mixed leukocyte rection suppressor factor (MLR-TsF), was characterized with respect to its kinetics of secretion and its sensitivity ot a variety of metabolic blocking agents. It was found that spleen cells from alloantigen-immunized mice released active MLR-TsF after freeze-thaw lysis. Upon restimulation with the same priming alloantigen, MLR-TsF was secreted into culture supernatants, and the rate of secretion was determined to be nearly constant. Although colchicine and vinblastine, which bind to microtubules, are known inhibitors of lectin-induced proliferation, it was demonstrated that these drugs had no effect on the secretion of MLR-TsF. However, cytochalasin B, an inhibitor which also binds to some cytoskeletal and membrane-associated proteins, did inhibit the production of MLR-TsF. The above findings indicated that the activation-secretion mechanism of of MLR-TsF was much like that described for lymphotoxin and macrophage migration inhibition factors. The dissociation between DNA synthesis and lymphokine secretion was also demonstrated in the MLR-TsF system. DNA synthesis plays no role in the in vitro production of suppressor factor, as determined by resistance to treatment with mitomycin C and gamma-irradiation. However, new protein synthesis is required as indicated by the potent inhibitory effects of cycloheximide. Experiments utilizing timed addition and removal of cycloheximide defined a broad period of drug sensitivity, starting from the beginning of culture and lasting for 12 to 16 hr. In addition, experiments measuring the effect of cycloheximide on the MLR-TsF content of cell lysates demonstrated that the cell-associated lymphokine activity is lost when protein synthesis is interrupted. These experiments support the conclusion that MLR-TsF is synthesized de novo in culture. In addition, the secretory process itself may require protein synthesis.

Animals↗
PubMed1979

Interaction between T cells and non-T cells in suppression of cytotoxic lymphocyte responses.

Generation of cytotoxic T lymphocytes (CTL) in mixed leukocyte cultures was suppressed by a factor elaborated by alloantigen-activated T cells. This suppressor factor, CTL-TsF, in contrast to a factor that suppresses proliferative responses in mixed leukocyte reactions (MLR-TsF), was effective only when added during the first 24 hr of a 6-day-culture period. Moreover, removal of CTL-TsF 24 hr after culture initiation failed to restore CTL responses. CTL activity could be rescued from suppressed cultures, however, by addition of 2-mercaptoethanol on days 3 or 4. Similarly, transfer of nonadherent cells at 3 or 4 days from cultures treated with CTL-TsF to cultures of adherent cells initiated in control factor restored CTL responses. Mixing experiments with cells pulsed with CTL-TsF for 4 hr at culture initiation identified a target of CTL-TsF as a Thy-1 negative cell that was adherent to plastic and to Sephadex G-10. Suppression was not due to interference with physiologic accessory cell function, but more likely was accomplished via a negative signal from CTL-TsF-pulsed cells. The results thus suggest that CTL-TsF acts early, but reversibly, in the CTL differentiative process via a second suppressor effector cell, possibly a macrophage.

Animals↗
PubMed1979

Human immune responses to hapten-conjugated cells. II. The roles of autologous and allogeneic histocompatibility determinants in proliferative responses in vitro.

Proliferative responses of human lymphocytes primed in vitro to autologous TNP-cells were found to be associated with autologous D-region determinants irrespective of HLA-B locus antigens. Family studies of secondary TNP-conjugate proliferative responses demonstrated a gene dosage effect in this phenomenon. Moreover, co-culture with allogeneic cells did not affect the net TNP-conjugate proliferative responses of primed responder cells, suggesting that HLA-D region preference was due to a requirement for representation of TNP-molecules in association or combination with autologous MHC structures. Alloantigens were found to influence the sensitization of lymphocytes to autologous hapten-conjugated cells. Co-culture of allogeneic and TNP-modified autologous stimulator cells in primary cultures enhanced the secondary TNP proliferative response. Sensitization of human lymphocytes to allogeneic cells alone did not prime responses to autologous modified cells. However, priming lymphocytes to modified autologous cells potentiated responses to allogeneic cells. The data suggest a complex relationship between responses to alloantigens and modified autologous cells.

Antibody Formation↗
PubMed1978

Human immune responses to hapten-conjugated cells. I. Primary and secondary proliferative responses in vitro.

An in vitro model was developed to study both primary and secondary proliferative responses of human lymphocytes to hapten-conjugated peripheral blood mononuclear cells. Coculture of human lymphocytes with autologous trinitrophenyl (TNP)-conjugated stimulator cells resulted in primary proliferative responses. Subjects segregated into high and low primary responders with mean stimulation indices of 11 and 2.1, respectively. Restimulation of primed cells from high responder subjects 3 wk after initial sensitization generated secondary proliferative responses. To investigate the antigenic requirements for secondary stimulation, autologous TNP-conjugate primed responders were restimulated with both autologous and allogeneic TNP-conjugated stimulators. In all experiments restimulation with autologous conjugated cells yielded substantially greater proliferative responses than with allogeneic conjugates. Experiments were then performed to ascertain whether HLA determinant homology between primed responder and stimulator cells influenced the level of secondary responsiveness. Homology for HLA-A and B locus serologic determinants was not associated with enhanced responsiveness. In contrast, D region determinant homology, detected by B-cell antigen typing, showed a highly significant positive correlation with the magnitude of secondary responses. The data thus strongly suggest that for secondary proliferative responses to TNP, human T cells recognize hapten in association with HLA-D region determinants.

Genes↗
PubMed1978

Suppression of cytotoxic lymphocyte responses in vitro by soluble products of alloantigen-activated spleen cells.

Suppression of in vitro cytotoxic lymphocyte (CL) responses was mediated by soluble factor(s) produced when in vivo alloantigen-activated suppressor cells were re-exposed to alloantigen in vitro. Elaboration of suppressor factor (SF) was T cell dependent and was optimal 7 days after alloantigen injection. Suppressor factor failed to inhibit CL generation when alloantigen-primed cells rather than normal spleen cells were used as responders. Moreover, SF added at day 3 of incubation rather than at culture initiation was also ineffective, suggesting that suppression probably occurs during antigen induction or early differentiation. Additionally, suppression was abrogated by the presence of 2-mercaptoethanol. Studies combining SF and CL responder cells from a variety of H-2 disparate mouse sdrains revealed that suppression of CL responses: 1) was not alloantigen specific; 2) did not require H-2 homology between responder and suppressor strains; and 3) could not be demonstrated with CBA/J mice. Although CBA/J CL responses were not suppressed by any SF preparation, allo-sensitized CBA/J spleen cells did elaborate SF that inhibited BALB/c CL responses.

Animals↗
PubMed1978

Regulation of alloantigen-induced cytotoxic responses by concanavalin A-activated lymphoid cells: suppression by antigen elimination.

Spleen cells activated by concanavalin A (Con A) and subsequently irradiated with 1500 R were able to suppress the primary in vitro cytotoxic lymphocyte (CL) response of syngeneic splenocytes to H-2 disparate targets. Similarly activated and irradiated BALB/c (H-2d) splenocytes which were cultured with C57BL/6 (H-2b) stimulators for 24 hr developed cytotoxicity for H-2b, but not H-2d, tumor cell targets. This suggested that Con A-activated cells allogeneic to the stimulator might suppress the development of cytotoxic lymphocytes by eliminating antigen early in mixed leukocytes culture. This hypothesis was supported by the observation that suppression of primary cytotoxic responses was overridden by the use of greater numbers of stimulator cells. Moreover, Con A-activated (A X B)F1 lymphocytes suppressed the response of parent A to the H-2 disparate strain C to a much greater extent than they suppressed A-anti-B responses generated in such cultures. Addition of greater numbers of F1 suppressor cells did reveal a suppressive effect not readily explicable on a cytotoxic mechanism, in that modest but significant suppression of the A-anti-B response was observed. Thus, antigen elimination is a major, but not exclusive, mechanism in the suppression of CL responses by Con A-activated cells.

Animals↗
PubMed1977

Regulatory mechanisms in cell-mediated immune responses. VI. Interaction of H-2 and non-H-2 genes in elaboration of mixed leukocyte reaction suppressor factor.

Previous studies have shown that alloantigen-activated spleen T cells produce a soluble factor which suppresses mixed lymphocyte reaction proliferative responses, and that the interaction between suppressor and responder cells is controlled by genes of the H-2 complex. However a defect in the expression of suppressor activity was identified in the mouse strain C57BL/6J. Factor prepared from alloactivated B6 spleen cells failed to suppress MLR responses of syngeneic or H-2 compatible responder cells. Unimpaired suppressor factor production by other H-2 (b) strains and failure of suppressor factor production by a B6 congenic strain, B6.C-H-2(d) isolated the defective gene to the non-H-2 portion of the genome. In addition, the defect appeared to be related specifically to inability to produce an active factor, while the capacity to respond to suppressor molecules was unimpaired. The genetic character of the non-H-2 gene action was identified in F1 hybrid studies. Initially F(1) hybrids of the nondefective histoincompatible strains were studied. Suppressor factor from F1 cells suppressed the responses of both parental strains, and parental factors each suppressed the response of F(1) cells. Adsorption of F(1) factor with Con A-activated thymocytes of either parental strain removed suppressor activity specific for that strain, leaving activity against the other parental strain intact. The data support cedominant expression and production of distinct, parental H-2 haplotype-specific suppressor molecules by F(1) suppressor cells. An F(1) hybrid of the defective B6 strain with nondefective BALB/c produced suppressor factor which was also capable of suppressing both parental strains. Production of a suppressive B6-reactive factor by F(1) cells was verified by adsorption studies. Thus it appears that non-H-2 genes of the BALB/c parent acted in a genetically dominant fashion to provide the function required for expression of B6 suppressor molecules. We conclude that multiple genes control the expression of alloactivated suppressor cell activity, with at least one gene mapped to the I-C subregion of the murine major histocompatibility complex and one or more genes mapped to the non-H-2 gene complement.

Animals↗