Diabetogenic T lymphocytes in human Type 1 diabetes

The field of Type 1 diabetes research has been quick to embrace the era of translational medicine in the recent epoch. Building upon some 30 years of intense immunological research, the past decade has been marked by a series of clinical trials designed to evaluate the potential beneficial effects of a range of immune intervention and prevention strategies [1
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• , 2, 3, 4 and 5]. At the heart of Type 1 diabetes is an autoimmune process, the consequence of which is immune-mediated destruction of islet β-cells. Although understanding the pathogenesis of islet autoimmunity is critical, there are also good reasons to focus research onto the β-cell destructive process itself. Measuring preservation of function of insulin-producing cells is currently the best means available to evaluate potential beneficial effects of immunotherapy, but there is an urgent need to discover and monitor immunological correlates of this β-cell destructive process. Whilst the best approach to intervention and prevention has yet to emerge, it is logical that future attempts to intelligently design therapeutics for Type 1 diabetes will need to be predicated on a clear understanding of the process of β-cell destruction and the immune components involved. For these reasons, this review will focus on the role of diabetogenic T lymphocytes in this disease-defining event.

► There is good reason to believe that T cells, both CD4 and CD8, can damage β-cells.
► A broad range of islet autoantigens, not all of them β-cell-specific, are targeted.
► There are multiple mechanisms via which diabetogenic T cells escape thymic selection.
► Diabetogenic T cells have low-avidity T cell receptors.
► Diabetogenic epitopes have low affinity interactions with HLA.