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R M Perlmutter

Publications and source records attributed to R M Perlmutter.

13 recordsLinked to original sources
PubMed1992

Defective T cell receptor signaling in mice lacking the thymic isoform of p59fyn.

Considerable evidence supports the hypothesis that the nonreceptor protein tyrosine kinase p59fyn participates in signal transduction from the T cell receptor (TCR). To examine this hypothesis in detail, we have produced mice that lack the thymic isoform of p59fyn but retain expression of the brain isoform of the protein. fynTnull mice exhibit a remarkably specific lymphoid defect: thymocytes are refractile to stimulation through the TCR with mitogen or antigen, while peripheral T cells, following what appears to be a normal maturation sequence, reacquire significant signaling capabilities. These data confirm that p59fynT plays a pivotal role in TCR signal transduction and demonstrate that additional developmentally regulated signaling components also contribute to TCR-induced lymphocyte activation.

Animals↗
PubMed1992

Disruption of CD8-dependent negative and positive selection of thymocytes is correlated with a decreased association between CD8 and the protein tyrosine kinase, p56lck.

The CD4 and CD8 coreceptor molecules on immature thymocytes participate in T cell repertoire selection. To examine more definitively the role of CD4 and CD8 in the negative and positive selection of immature thymocytes, we generated transgenic mice with elevated surface CD4 expression and mated them with mice expressing a transgenic T cell receptor. Augmented CD4 expression was found to markedly alter CD8-dependent negative and positive selection of T cells specific for the male (H-Y) antigen presented by H-2Db major histocompatibility complex class I molecules. Moreover, the cytoplasmic tail of CD4 was essential for effecting these alterations, since the overexpression of tailless CD4 molecules failed to influence the outcome of CD8-dependent selection. The inhibition of positive and negative selection in double-transgenic mice expressing the full-length CD4 molecule was associated with a decreased interaction between the protein tyrosine kinase p56lck and CD8. These results strongly implicate p56lck in T cell repertoire selection.

Animals↗
PubMed1992

Inhibition of T-cell receptor beta-chain gene rearrangement by overexpression of the non-receptor protein tyrosine kinase p56lck.

The variable region genes of the T cell receptor (TCR) alpha and beta chains are assembled by somatic recombination of separate germline elements. During thymocyte development, gene rearrangements display both an ordered progression, with beta chain formation preceding alpha chain, and allelic exclusion, with each cell containing a single functional beta chain rearrangement. Although considerable evidence supports the view that the individual loci are regulated independently, signaling molecules that may participate in controlling TCR gene recombination remain unidentified. Here we report that the lymphocyte-specific protein tyrosine kinase p56lck, when overexpressed in developing thymocytes, provokes a reduction in V beta--D beta rearrangement while permitting normal juxtaposition of other TCR gene segments. Our data support a model in which p56lck activity impinges upon a signaling process that ordinarily permits allelic exclusion at the beta-chain locus.

Animals↗
PubMed1992

Functional dissection of the lck proximal promoter.

The lck gene encodes a protein tyrosine kinase that participates in lymphocyte-specific signal transduction pathways. Previous studies have established that lck transcription is regulated by two distinct promoter elements termed proximal (or 3') and distal (or 5'). The proximal promoter is active almost exclusively in thymocytes and becomes inactive later during T-cell maturation. To dissect the mechanisms responsible for lck gene regulation, we generated transgenic animals bearing 5' truncations in the proximal promoter element. Sequences between -584 and +37 with respect to the proximal promoter transcription start site act to direct tissue-specific and temporally correct transcription of either a tagged version of the lck gene itself or a heterologous reporter sequence (lacZ). This region contains binding sites for at least five distinct nuclear proteins, of which one is found only in cells that support proximal lck promoter activity and a second appears only in nonexpressing cells. Interestingly, the transcribed region of the lck gene contains positive control elements that can substantially boost expression from minimal (-130 bp) proximal promoter constructs. These results provide a basis for the biochemical dissection of transcriptional regulators that act at defined points during T-cell development.

Animals↗
PubMed1979

Immunoglobulin subclass-specific immunodeficiency in mice with an X-linked B-lymphocyte defect.

CBA/N mice express an X-linked deficiency in their antibody response to many bacterial carbohydrates; we have shown recently that these antigens normally elicit antibody responses predominantly of the IgM and IgG3 isotypes. Here we demonstrate that mice, with the CBA/N phenotype have perferential deficiencies of IgM and IgG3 immunoglobulin expression, both when measured in serum and in cells secreting these isotypes, and that this deficiency is only partially corrected by polyclonal activation of B cells. This suggests that CBA/N mice may lack a subpopulation of B cells that contain most of the IgG3 precursors.

Animals↗
PubMed1979

Immune response deficiency of BSVS mice. II. Generalized deficiency to thymus-dependent antigens.

BSVS mice gave abnormally low IgG responses to 5 thymus-dependent antigens as well as a weak delayed-type hypersensitivity (DTH) response to sheep red blood cells. In contrast to IgG, the IgM antibody responses of these mice were normal to three T-independent antigens as well as to all five T-dependent antigens. The low immune responsiveness of BSVS mice was also reflected in the low levels of IgG(2)a, IgG(2)b and IgG(3) in their normal serum. The low T-dependent immune responses may result from BSVS mice having been selectively bred for susceptibility to infection with St. Louis encephalitis virus and Salmonella. C57BL/6J mice, which are also highly susceptible to Salmonella, gave low immune responses similar to, but genetically distinct from, those of BSVS mice. The levels of Ig-positive and theta-positive cells were normal in BSVS and C57BL/6J mice.

Animals↗
PubMed1978

Analysis of the diversity of murine antibodies to dextran B1355. III. Idiotypic and spectrotypic correlations.

Examination of 19 S and 7 S anti-alpha(1 leads to 3) dextran (Dex) antibodies by serological assays and isoelectric focusing (IEF) has revealed substantial variation of idiotypic and spectrotypic expression between individuals of the same genotype. 7 S antibodies appeared to be more heterogeneous than 19 S by both methods. A strong, but complex, association was found between the IEF patterns of 19 S and 7 S anti-Dex antibodies and their expression of the idiotypic determinant(s) common to both the M104 and J558 dextran-binding myeloma proteins. However, no such relationship was found between the IEF pattern and the expression of idiotypic determinant(s) unique to the M104 myeloma protein. Rather, indistinguishable spectrotypes from different individuals have widely differing levels of expression of the determinant. In addition, this determinant(s) may be present on different spectrotypes of the same isotype. Both the M104 and J558-specific idiotypes were found on antibodies of the IgG3 subclass as well as in pools containing predominantly the IgG2a subclass. These data confirm and extend the picture of substantial structural variation among the antibodies comprising a response of restricted heterogeneity.

Animals↗
PubMed1978

Subclass restriction of murine anti-carbohydrate antibodies.

Examination of the subclass distribution of murine antibodies directed against groups A and C streptococcal carbohydrate, alpha-(1 leads to 3) dextran and phosphocholine yields the surprising observation that these carbohydrate antigens stimulate IgG responses largely restricted to the rare IgG3 subclass. This subclass restriction is particularly impressive in light of the low circulating levels of IgG3 in nonimmune mouse serum and the failure of a variety of other antigens including proteins and aromatic haptens to stimulate IgG3 antibody production. Attempts to alter the subclass restriction of antibodies with carbohydrate specificity by immunization with carbohydrate-coupled protein have been unsuccessful and indicate that immunoregulation of subclass expression probably occurs at the level of the antibody forming (B) cell. It is therefore conceivable that VH regions of murine immunoglobulins may be restricted to particular IgG subclasses. A similar type of subclass restriction has been reported in human and rat anti-carbohydrate antibodies. This recruitment of a minor immunoglobulin isotype by carbohydrate antigens in several species further supports the concept of immunoregulation at the level of subclass, and suggests that these and other mammals may share a structurally similar isotype with perhaps a common evolutionary origin.

Animals↗
PubMed1978

Light chain diversity of murine anti-streptococcal antibodies: IgCH-linked effects on L chain expression.

L chains derived from anti-group A streptococcal carbohydrate antibodies raised in A/J, BALB/cJ, C57BL/6J, CB-20, BAB-14, and CAL-20 mice were examined by isoelectric focusing. Multiple strain-associated differences in the degree and frequency of expression of particular L chain spectrotypes were observed. Analysis of L chain-focusing patterns in allotype-congenic mice revealed that IgCH-linked genes can have profound effects on the L chain phenotypes expressed by strains with identical L chain genotypes. Lastly, the overall spectrotypic diversity of L chains from anti-GAC antibodies appears to be less extensive than the diversity of the antibodies from which these L chains derive, documented by similar techniques. These results are interpreted in light of the significance of combinatorial diversity in generating antibody heterogeneity.

Animals↗
PubMed1977

Complete sharing of light chain spectrotypes by murine IgM and IgG anti-streptococcal antibodies.

In order to examine the diversity of antibody light chains, we have developed an analytic isoelectric focusing procedure which permits the routine analysis of L chains from antibodies raised in individual mice. We have used this technique to demonstrate that the light chains of IgM and IgG anti-group A streptococcal antibodies raised in SWR mice are probably shared. Interestingly, numerous light chain spectrotypes are shared between individual mice whose 7S antibody focusing patterns differ.

Animals↗
PubMed1977

Characterization of molecular heterogeneity and multispecificity in homologous idiotypic antisera.

The molecular heterogeneity of homologous anti-idiotypic reagents was characterized by a novel isoelectric focusing procedure. Idiotypic antisera directed against the PC-binding plasmacytoma protein T15 were raised in CE and and A/J mice. These antisera were shown to be highly specific by hemagglutination with myeloma protein-derivatized sheep erythrocytes and by radioimmunoassay. Competition experiments performed with affinity-labeled T15 revealed that about 40% of the pooled CE antibody activity was directed against binding site-associated determinants. Further analysis of anti-idiotypic sera from individual animals with the use of isoelectric focusing disclosed heterogeneous populations of antibody molecules distinguishable by isoelectric point and by subspecificity. Each animal expressed a unique spectrotypic profile. In addition, clones reactive with binding site and non-binding-site determinants as well as some clones with specificity for other PC-binding mouse myeloma proteins were detected. These results emphasize the importance of careful selection and thorough absorption of idiotypic antisera.

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