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B T Huber

Publications and source records attributed to B T Huber.

At least 91 records · Page 5Linked to original sources
PubMed1984

A class II gene conversion event defines an antigen-specific Ir gene epitope.

To assess the role of Ia epitopes in conferring specificity for the immune response to nominal antigen, we compared the insulin response of mice with a defined mutation in the I-Ab beta gene, the B6.C-H-2bm12 (bm12), with that of wild-type H-2b C57BL/6 (B6) mice. We report that the bm 12 mutation resulted in a selective alteration of the specificity of insulin recognition, such that bm 12 mice responded upon immunization with sheep but not beef insulin, which differ by only one amino acid at position 9 of the insulin A chain. Thus, the bm12 mutation allows for the definition of the actual nucleotide sequence coding for an Ia epitope that is responsible for controlling the specificity of immune recognition of insulin. Furthermore, we show that the sheep insulin response of H-2k mice is controlled by the E molecule and that sheep insulin can be recognized by primed bm12 and H-2k T cells in the context of either bm12, B10.A, or B10.A(5R) antigen-presenting cells. Our data suggest that the mechanism for the bm12 mutation was the intergenic transfer of a hypervariable region in the first domain that is identical in the I-Abm12 beta, I-Eb beta, and I-Ek beta genes.

Animals↗
PubMed1984

Immune recognition of insulin by H-2b mice: the mutation in the I-Ab beta gene of the B6.C-H-2bm12 mouse alters the self-I-A-restricted T cell repertoire.

The response to heterologous insulin in H-2b mice is restricted to the A chain loop determinant(s) of beef insulin. The recognition of this specificity requires the expression of the immune response (Ir) gene epitope Ia.W39 which is absent from the I-Ab mutant B6.C-H-2bm12 (bm12) mice. This restriction could reflect the inability of H-2b antigen-presenting cells (APC) to present other insulin determinants or may reflect "self-major histocompatibility complex"-dependent influences on the generation of the T cell repertoire. To assess these possibilities we analyzed the genetic control and fine specificity of the insulin-specific T cell repertoire of H-2b mice by fusing the AKR thymoma BW5147 with T cells of C57BL/6 mice which had been immunized in vivo and challenged in vitro with beef insulin. The cloned hybridomas that we have produced respond to APC either alone or in conjunction with insulin by the production of interleukin 2. The insulin-specific hybridomas vary in their fine specificity such that some clones recognize a determinant(s) shared by beef, sheep and pork insulin and the isolated B chain, while other clones recognize a determinant(s) shared by beef and sheep insulin only, likely to involve amino acids 8 and/or 10 of the A chain loop. The presentation of insulin to these hybridomas is restricted by I-Ab, but not by Ia.W39. This analysis revealed that the insulin-specific immune potential in H-2b mice is of greater scope than previously defined and led us to consider, whether insulin nonresponder bm12 mice also possess a latent insulin-specific immune potential. Our study of the insulin-specific immune recognition by bm12 mice shows that these nonresponders do possess insulin-specific T cell clones. Despite the fact that the I-Ab and I-Abm12 gene products differ only by 3 amino acids, insulin-specific C57BL/6 and bm12 hybridomas are restricted to recognize exogenous antigen only in the context of C57BL/6 and bm12 APC, respectively. Furthermore, upon direct analysis of autoreactive subclones, a similar although not complete, restriction was observed. The implications of these findings for understanding the mechanism of Ir gene control are discussed.

Animals↗
PubMed1984

B cell activation potential of insulin-reactive T cells in H-2b mice.

The murine T cell response to heterologous insulins provides a good model system for studying the mechanism of immune response (Ir)-gene function, since insulin is a small, chemically well-defined molecule. H-2b mice respond predominantly to A chain loop determinants of beef insulin, presented by the I-A epitope Ia. W39. However, using a library of insulin-specific T cell hybridomas (THy), we previously found that immunization of H-2b mice with beef insulin activates a much wider population of T cells than are detected in T cell proliferation assays. Using such cloned THy we were able to study Ir-gene control at the level of antigen presentation. We compared the ability of the various THy to induce differentiation in I-A-matched B cells in response to antigen. Although both A and B chain-reactive clones respond with interleukin 2 production, they differ markedly in their potential to activate B cells in that only the former are able to induce B cell differentiation in the presence of the intact beef insulin molecule. The latter, however, can serve as helper cells in the presence of isolated B chain, and can synergize with a suboptimal concentration of A chain-reactive THy to induce an optimal B cell response. These results suggest that the insulin molecule is presented by I-Ab antigen-presenting cells in a very specific configuration that allows more effective T cell recognition of the A chain loop than the B chain determinants. To explain the discrepancy between the interleukin 2 assay and the induction of polyclonal activation, it can be assumed that in the former assay antigen is presented by macrophages, while presentation by B cells is necessary for induction of polyclonal activation. Macrophages are able to process the intact beef insulin molecule and, therefore, present B chain determinants, while nonimmune B cells may be unable to process antigen and could present B chain determinants only when the isolated B chain is given as antigen.

Animals↗
PubMed1984

Selective activation by thymus-dependent antigens of distinct B cell subpopulations expressing a major cross-reactive idiotype.

We determined the B cell subpopulations that produce the major cross-reactive idiotype (CRIA) associated with the anti-phenylarsonate (ARS) antibody response of A/J mice. Specifically, we examined the B2 subpopulation found in normal mice which, in H-2b mice, bears the I-Ab-encoded determinant Ia.W39; the B1 subpopulation found in mice expressing the CBA/N X-linked immunodeficiency trait (xid); and the B1 subpopulation found in normal mice after the cytotoxic elimination of B2 cells with anti-Ia. W39 and complement. CRIA is expressed in each of these B cell subpopulations. Antigen plays a selective role in the stimulation of distinct B cell sets. ARS conjugates of keyhole limpet hemocyanin (KLH) can activate both the B1 and B2 subpopulations. In contrast, ARS conjugates of synthetic polypeptides under Ir gene control selectively activate the B2 subpopulation in strains that are genetic responders to the carrier. This leads to the establishment of CRIA dominance where CRIA+ anti-ARS antibody is 70 to 95% of the total anti-arsonate antibody response. This class of antigens fails to activate the B1 cells in either normal or xid mice. We compared the CRIA+ antibody produced by selectively activated B2 cells to that produced by the B1 subpopulation in xid mice. For these comparisons, we used competitive radioimmunoassays that employed polyspecific anti-CRIA antiserum or monoclonal anti-CRIA antibodies specific for distinct idiotopes on the heavy chain of CRIA+ antibody. B2 cells produce a CRIA+ anti-ARS antibody that is idiotopically uniform among individual mice, and that closely approximates the hybridoma protein 36-65 (the heavy chain of 36-65 represents the germ line-encoded sequence of the unique CRIA structural gene (25]. In contrast, the CRIA+ antibody produced by the B1 cell subset of xid mice is idiotopically diverse among individual mice, and differs markedly from the 36-65 hybridoma protein. The extent of diversification found in CRIA+ antibody depends on the B cell subpopulation that produces it.

Animals↗
PubMed1982

Role of Ia. W39 in the interaction of antigen-presenting cells with T and B lymphocytes.

Ia. W39 is a B cell differentiation antigen whose membrane expression is controlled by the xid gene. In this report we show that, analogous to its B cell expression, Ia. W39 is also present on a subset of Ia+ macrophages, indicating heterogeneity within that cell population. The Ir gene(s) for the antigenic determinants on the A chain loop of beef insulin maps to the I-Ab subregion of the H-2 complex and, as we have previously reported, is associated with the private specificity Ia. W39. Depletion of Ia. W39+ macrophages eliminates their capacity to present beef insulin to immune T cells, whereas the presentation of the multideterminant antigen trinitrophenylated ovalbumin is reduced less than 50%. Furthermore, we found that H-2b mice lacking Ia. W39+ cells are unable to make a secondary in vivo IgG plaque-forming cell (PFC) response to beef insulin, while the primary IgG PFC response is not dependent on Ia. W39. No shift in the kinetics of the response, nor development of suppressor T cells could be detected in Ia. W39- mice, which would explain their apparent nonresponsiveness to beef insulin after boosting with this antigen. These results, therefore, may reflect a difference in the Ir gene control acting at the primary vs. secondary response level.

Animals↗
PubMed1982

B cell differentiation antigens as probes for functional B cell subsets.

In this review I have discussed the serological, biochemical and functional characterization of two differentiation antigens, Lyb3 and Ia. W39, which have the same time distribution; namely, they are selectively expressed on a late maturing subset of B cells (Lyb3 and Ia. W39) and antigen presenting macrophages (Ia. W39, Lyb3?) Antisera against both determinants were raised in xid defective F1 male mice, which were immunized with spleen cells from the normal parent. Lyb3 is an isogenic specificity expressed without allelic forms in all mouse strains, whereas Ia.W39 is a private specificity, encoded by a gene(s) within the I-Ab subregion of the H-2 complex. Interestingly, the xid gene does not control the synthesis of these differentiation antigens, but affects their membrane expression (shown for Ia. W39.) Lyb3 is a polypeptide of 68,000d MW which has a similar IE point in all mouse strains. The molecule bearing Ia. W39 has an identical 2-chain structure (a and beta) and 2-D gel profile as the molecule expressing all the conventional Ia specificities encoded by the I-Ab subregion. However, from the difference in the ontological appearance and the turnover rate and from sequential immunoprecipitation studies we concluded that there are two kinds of glycoproteins containing Aa and Abeta chains; both would express the conventional specificities, and one would, in addition, bear Ia. W39. Functionally, we have defined Lyb3 as a receptor for triggering signals and Ia. W39 as a specific Ir gene epitope.

Animals↗
PubMed1982

Lyb3: a B cell surface antigen associated with triggering secretory differentiation.

The results discussed in this review show that the TNP-specific IgA lambda 2-secreting BALB/c plasmacytoma MOPC-315 is partially composed of small lymphocytoid, presecretory cells which express the Lyb3 determinant. It is shown that MOPC-315 cell secretory differentiation, but not clonal proliferation, can be modulated by anti-Lyb3. Anti-Lyb3 serum has been shown to: 1) augment secretory differentiation enhancement by suboptimal numbers of secretory differentiation-enhancing, IgA315-specific helper T cells; 2) replace this secretory differentiation-enhancing T cell population as long as clone growth helper T cells are present; and 3) block suppression of secretory differentiation mediated by carrier-immune Ts cells. These results demonstrate that whether anti-Lyb3 serum enhances immune responses by replacing or augmenting a helper signal or by counteracting suppressor signals, the effects are focused on secretory differentiation events and have no effect on clonal proliferation.

Antibodies, Monoclonal↗
PubMed1982

Ia.W39 expression correlates with a specific Ir function.

The xid- defective mouse (N X B6)F1 male and the I-Ab mutant of the B6 mouse bm12 have mutations on different chromosomes, and therefore in separate genes. However, both variant strains have a trait in common; namely, they are unresponsive to the A chain loop determinant(s) of beef insulin to which mice of the H-2b haplotype respond. We show here that in both mutant strains, this unresponsiveness is concurrent with the absence of the Ia.W39 specificity from the M phi and B cell surface. The concordance is specific for Ia specificity W39 and no other Ia determinant, suggesting that Ia.W39 is identical with the Ir epitope necessary for generating an immune response to a particular amino acid sequence of beef insulin. In the xid-defective mouse, the molecule carrying this antigen is synthesized but not expressed on the plasma membrane, presumably because a mature M phi and B cell subset is missing. By comparison, the bm12 mouse has mature B lymphocytes, but is unable to synthesize Ia.W39. Thus, bm12 has a structural mutation in the gene coding for Ia.W39, whereas xid is a mutant regulatory or maturation gene controlling the membrane expression of Ia.W39.

Animals↗
PubMed1981

The xid gene controls Ia.W39-associated immune response gene function.

Immune response (Ir) genes are encoded for by the I region of the major histocompatibility complex (MHC). A class of serologically defined specificities, Ia antigens, is also encoded for by genes within this region. A new Ia specificity, Ia.W39, has recently been defined. It is private for I-Ab and its expression is controlled by a gene on the X-chromosome. Using different approaches, the role of Ia.W39 in the immune response of H-2b mice to beef insulin was examined in a macrophage-dependent T cell proliferation assay. It was found that beef insulin-related Ir gene function was associated with the expression of Ia.W39 by antigen-presenting macrophages and that control of this Ir gene function was X-linked (xid gene).

Animals↗
PubMed1981

Effect of anti-Lyb3 antiserum on poly (L-glutamic acid, L-lysine)-induced B cell tolerance.

The effect of anti-Lyb3 antiserum on antigen-specific B cell tolerance was investigated. The intraperitoneal injection of the nonimmunogenic copolymer L-glutamic acid60, L-lysine (GL) specifically reduces the ability of murine B cells to form GL-specific plaque-forming cell responses following challenge with the immunogenic conjugate of GL coupled to fowl gamma-globulin. It was found that this tolerance could be reversed or blocked by the intravenous injection of microliter quantities of anti-Lyb3 antiserum. However, this dose of antiserum neither reversed T cell tolerance induced with protein-coupled syngeneic erythrocytes nor induced tolerized B cells to secrete antibody. The results suggest that B lymphocytes can be rescued from GL-induced tolerance soon after induction and that Lyb3 determinants may play a functional role in the activation of antigen-specific B lymphocytes.

Animals↗
PubMed1981

Primary and secondary in situ antibody response: abnormal affinity maturation pattern in mice carrying the xid gene.

The xid gene in mice controls a recessive defect resulting in the absence of a late maturing subset of B cells. Whereas the responsiveness pattern of these mice have been clearly defined in terms of their ability or inability to make antibodies to certain classes of thymus-independent antigens, there are conflicting reports in regard to affinity maturation of the antibody response to thymus-dependent antigens. To resolve this controversial issue, the two major isotypes of the IgG response, namely IgG1 and IgG2a were examined with a highly sensitive radioimmunoassay that measures both the magnitude and affinity of the anti-2,4-dinitrophenyl antibody of each isotype in individual serum samples. It was found that the xid gene reduced the amount but not affinity of the IgG1 antibody produced, whereas it impaired the whole IgG2a responses severely. In fact, mice carrying the defective gene were unable to mount a secondary IgG2a response, measured either quantitatively or qualitatively in terms of increased affinity. To test the possibility that Lyb3, an isogenic B cell-triggering receptor lacking in xid-mutant mice, plays a direct role in the maturation of the immune response, the antibody profile in normal mice immunized eigher with antigen alone or in combination with anti-Lyb3 receptor substantially elevated and accelerated the primary IgG2a response, whereas it had little effect on the IgG1 response.

Animals↗
PubMed1981

Structural analysis of a new B-cell-differentiation antigen associated with products of the I-A subregion of the H-2 complex.

Ia.W39 is a private specificity of the I-Ab subregion of the H-2 complex. It is selectively expressed on a subset of B lymphocytes that is absent in newborn normal and adult mutant mice carrying the xid gene. Immunoprecipitation and one-dimensional NaDodSO4/polyacrylamide gel electrophoresis showed that the molecule bearing Ia.W39 consists of two noncovalently linked glycoproteins of apparent Mr 33,000 and 28,000. Anti-Ia.W39 serum did not preclear the Iab molecule; however, the conventional allo-anti-I-Ab serum cleared Ia.W39 completely. In view of the identical two-dimensional gel pattern generated by the Ia.W39 and the conventional Iab immunoprecipitates, we believe that all Ia molecules bear the conventional specificities and only a subset would in addition express Ia.W39. Ia.W39 is probably not a carbohydrate antigen, because the antibiotic tunicamycin had no influence on its expression. It may be a conformational determinant on the A alpha and A beta complex induced by the association of an unknown molecule with these chains.

Age Factors↗
PubMed1981

Prevention of tolerance induction by simultaneous administration of anti-Lyb3 antiserum with tolerogen.

Lyb3 serves as a triggering receptor on a mature subset of B lymphocytes. To further investigate the nature of the activating signal received by this receptor, we examined its involvement in hapten-specific B cell tolerance induced in vivo with isologous IgG. We obtained the following results: injection of anti-Lyb3 serum simultaneously with low doses of tolerogen prevented tolerance induction in B cells responsive to TD and TI type-1 antigens but failed to influence B cells responding to a TI type-2 antigen. Furthermore, administration of anti-Lyb3 serum did not change the tolerogenic signal to an immunogenic one, allowing B cell maturation into plaque-forming cells. However, it did make the B cell responsive to a subsequent challenge with antigen. This effect is transient, and dependent on the dose of tolerogen. These results are discussed in terms of our knowledge of the mechanism of B cell tolerance.

Animals↗
PubMed1979

Antigenic marker on a functional subpopulation of B cells, controlled by the I-A subregion of the H-2 complex.

CBA/N mice have an X-linked recessive effect that results in the absence of a subpopulation of B cells carrying the Lyb3 surface marker. It has been shown previously that this marker is present on a mature subset of B cells in all mouse strains. In this paper the Lyb3+ B cell population in C57BL/6 mice was analyzed further. This subset of B cells selectively expresses a surface marker controlled by the I-A subregion of the H-2 complex. A cytotoxic antiserum recognizing this marker was raised by immunizing defective (CBA/N X C57BL/6)F1 male mice with C57BL/6 spleen cells. This antiserum also contained noncytotoxic, non-strain-restricted anti-Lyb3 antibodies. The possible functional relevance of this surface marker is discussed.

Animals↗
PubMed1979

Localization of spontaneously hyperactive B cells of NZB mice to a specific B cell subset.

NZB mice produce numerous autoantibodies and have a subpopulation of B cells characterized by marked spontaneous hypersecretion of IgM. The latter trait is determined by autosomal genes, in F1 hybrids of NZB and normal strains. We tested the hypothesis that the hypersecreting B cells of NZB mice are contained within a specific subpopulation by examining (CBA/N X NZB)F1 hybrids. CBA/N mice have an X-linked recessive defect that results in the absence of a functionally distinct B cell subpopulation and impaired antibody responses. The hyperactivity of B cells, characteristic of the NZB parent, was transmitted to the F1 female, but was not expressed by the F1 male, which manifested the CBA/N B cell hyporesponsiveness. By contrast, the NZB xenotropic virus was expressed equally by both male and female F1 mice. We conclude that the NZB B cell abnormality resides within the B cell subpopulation affected by the CBA/N mutation.

Animals↗
PubMedDate not supplied

Superantigens.

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Animals↗