Flexibility of the T cell repertoire. Self tolerance causes a shift of T cell receptor gene usage in response to insulin.

Abstract

Bovine insulin(BI)-specific I-Ab-restricted T cell clones have been characterized for fine specificity and TCR gene usage. We have demonstrated that mouse strains carrying H-2b on three different genetic backgrounds (C57BL, BALB, and 129) rearrange and express the V beta 6 gene in a large proportion (36%) of insulin-specific clones. In these strains, the non-MHC background did not seem to influence TCR gene usage in response to BI. The V beta 6+ clones appeared to be selected by the antigen. In contrast, no V beta 6+ clones could be isolated from (B6 x DBA/2)F1 mice, where V beta 6+ (and V beta 8.1+) T cells are deleted by self tolerance to Mls-1a. Thus, although a small proportion of residual V beta 6+ cells had been demonstrated in Mls-1a mice, these cells could not be retrieved in a response that uses V beta 6 predominantly. In functional terms, therefore, the deletion of V beta 6 by self tolerance appears to be complete. Instead of V beta 6, the majority (up to 60%) of I-Ab- as well as I-Ad-restricted insulin-specific clones from the (B6 x DBA/2)F1 mice expressed V beta 8.2 and V beta 8.3. This shift of gene usage was not accompanied by any detectable change in the fine specificity pattern of response. Thus, in the insulin-specific response, the flexibility of T cell repertoire fully compensates for deletions caused by self tolerance.

Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant.

“…Processing is inhibited by chloroquine or prior fixation of APC. Disruption of the disulfide bonds in insulin by performic acid oxidation or reduction and alkylation destroys its capacity to stimulate cloned and polyclonal T cells (8,12,13,17). This can be interpreted to indicate that an intact A chain loop structure or disulfide-linked B chain residues are essential components of the major determinant.…”

“…The authors concluded that the T cells recognized a confor-mational determinant containing essential residues from both the A and B chains of insulin. Others have described experiments in which mouse and human A chain loop-reactive T cells were stimulated by A chain peptides with no associated B chain residues (9)(10)(11)(12)(13). These results indicate that at least some loop-reactive T cells recognize determinants within the A chain.…”

“…3). Fixed TH2.2 B cells were pulsed with various concentrations of A (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) in the absence of serum, washed, and cultured with T cell hybridomas. The presence of DTT during the peptide pulse did not affect the capacity of the treated APC to stimulate T cells, in contrast to our results with insulin.…”

“…However, it seems ~2~ a unlikely that a disulfide bond between the loop cysteines, A6 and All, would form in reduced A (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) in the presence of DTT. Results similar to those obtained with air-oxidized A (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) were observed in experiments using sulfonated A chain. Fixed APC pulsed with sulfonated A chain in the presence, but not the absence, of DTT were capable of stimulating Bd-l.4 and Bb-6 ( Fig.…”

Negative segregation of Mtv loci in H-2E + mice selected for high antibody response

“…M. Seman Laboratoire d'Immunodiff6renciation, Hall de Biotechnologies, Universit6 Denis Diderot (Paris 7), BP 7124, 2 place Jussieu, F-75251 Paris Cedex 05, France see Tomonari et al 1993). Tcr diversity resulting from VJ or VDJ recombinations and N sequences generates alternative repertoires to conventional Ags that might prevent deletion of Tcrb-V-expressing T cells induced by Sags to profoundly alter the immunological responder status (Davis and Bjorkman 1988;Frangoulis et al 1989;Falcioni et al 1990). Yet, a controversy exists as to whether T-cell clone anergy or deletion induced by Sags might contribute to the immunodeficiency observed in mice infected by the mouse leukemia virus or in HIV-infected patients (Htigin et al 1991;Imberti et al 1991;Kanagawa et al 1992;Laurence et al 1992).…”