Identification of an autologous insulin B chain peptide as a target antigen for H-2Kb-restricted cytotoxic T lymphocytes.

Abstract

SLlnlnlAryWe have examined the CD8 + peripheral T cell repertoire of C57BL/6 (H-2 b) mice for cytotoxic T lymphocyte (CTL) reactivities to insulin, using in vitro immunization with a chymotryptic digest of reduced bovine insulin. The results presented in this study demonstrate that potentially autoreactive H-2Kb-restricted cytotoxic T cells specific for an autologous insulin B chain peptide are present in the preimmune splenic T cell repertoire. The immunogenic peptide comprises residues 7-15 from the insulin B chain and has features in common with naturally processed Kb-restricted peptides identified by others. The minimal peptide sequence recognized by these cytotoxic T cells is 10-15, which is highly conserved in mammalian species and constitutes a self-peptide in mice. The presence of class I major histocompatibility complex-restricted CTLs with potentially autoreactive specificities in preimmune animals raises the possibility of a role for such ceUs in autoimmune disease states. Possible mechanisms for the in vivo expansion of insulin peptide-specific CTLs are discussed.

Low Dose Streptozotocin-Induced Diabetes in Rat Insulin Promoter-mCD80-Transgenic Mice Is T Cell Autoantigen-Specific and CD28 Dependent

“…Moreover, we did detect minor CTL responses toward the subdominant LCMV-gp epitope (gp276) as well (Table II). However, we did not detect responses toward a H-2K b -restricted CTL epitope derived from the bovine insulin B chain (InsBp7) reported to elicit H-2K b -restricted CTL responses due to cross-reactivity with a mouse insulin epitope (27). Most notably, in the absence of LCMV-gp, IIL displayed no significant increase in IFN-␥ secretion upon gp33 stimulation.…”

“…The next day, islet suspension cells were stimulated with peptide-loaded EL-4 target cells (H-2 b , ATCC) in the presence of 1 mol Monensin (Fluka, Neu-Ulm, Germany). In addition to gp33 and np396, we also used a subdominant LCMV-gp CTL-epitope, gp276 (aa 276 -286, SGVENPGGYCL) (26), and an epitope derived from bovine insulin B chain, InsBp7 (aa 7-15, CGSHLVEAL) as reported (27). To estimate the maximal frequency of responding cells, positive controls were stimulated with 5 ng/ml PMA plus 500 ng/ml ionomycin (both obtained from Sigma).…”

Cryptocrine signaling in the thymus network and T cell education to neuroendocrine self-antigens

“…Therefore those sequences might be considered as self-antigens of insulin-related polypeptides. Interestingly, these sequences closely correspond to the target antigen of cytotoxic T cells oriented against insulin [45]. Such a correspondence between highly conserved sequences and dominant antigens has also been noticed recently by others [36].…”

“…IGF-II is very homologous but not identical to insulin, and this biochemical difference could elicit completely opposite immune responses. Indeed, while insulin has been shown to activate autoreactive cytotoxic T cells [45], IGF-II could program their tolerant state. These differences in the biochemical identity and immunological responses elicited by insulin-related antigens could be fundamental for the design of an efficient and secure prevention of autoimmune IDDM.…”

Inhibition of naïve class I‐restricted T cells by altered peptide ligands

“…If the antagonism we observed was the result of a non-specific MHC competition, then some effect would likely have been observed by all the peptides used. That is, the irrelevant control peptide (known to bind H-2Kb; indeed, CTL have been generated against it 27 ) and altered OVAp with substitutions at non-TCR contact residues should also have antagonized proliferation and CTL activity, which was not the case. Notably in addition, peptides that compete for MHC binding usually require 100-fold levels to antagonize cognate peptides.…”