The potential role of the heat shock protein hsp 60 in the development of diabetes in NOD mice was first postulated by Elias et al. (6,7). This hypothesis was based on the detection of T-cell and antibody responses against a 62-kDa molecule cross reactive with a mycobacterial 65-kDa heat shock protein. These hsp 65 cross-reactive T-cell and antibody responses developed coincidently with the progression of insulitis and were followed by induction of anti-insulin antibodies and anti-idiotypic antibodies (6). An isolated diabetogenic T-cell clone was able to transfer disease to naive mice. The importance of the hsp 60 cross-reactive immunity in the pathogenesis of NOD mice diabetes was supported further by the finding that administration of hsp 60 antigen or synthetic peptide epitope to young NOD mice protected them against diabetes (7). These results provided strong evidence that one of the antigens in diabetes is related to hsp 60.
Since the epitope on mycobacterial hsp 60 recognized by diabetogenic T helper cells was similar to human hsp 60 (7), it was assumed that the endogenous protein bearing this epitope might serve as an autoantigen. The natural candidate then for hsp 65 cross-reactive immunity was mitochondrial hsp 60.
The concept of hsp 60 as an antigenic target in type I diabetes evoked much controversy (57-59). It was hard to envision how a ubiquitous protein such as hsp 60, present in every cell in the body, could play a role in an organ-specific disease, and why a mitochondrial antigen, an intracellular^ located protein physically separated from access to the immune system by mitochondrial membranes, could elicit immune responses.
Therefore, in order to determine the significance of the hsp 60 proteins in the pathogenesis of type I diabetes, we have undertaken systematic analysis of the localization and distribution of endogenous antigens recognized by hsp 60 antibodies in pancreatic (3 cells.
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