Single Insulin-Specific CD8+ T Cells Show Characteristic Gene Expression Profiles in Human Type 1 Diabetes

OBJECTIVE-Both the early steps and the high recurrence of autoinununity once the disease is established are unexplained in human type I. diabetes. Because CD8(+) T cells are central and insulin is a key autoantigen in the disease process, our objective was to characterize HLA class I-restricted autoreactive CD8(+) T cells specific for preproinsulin (PPI) in recent-onset and long-standing type I diabetic patients and healthy control subjects. RESEARCH DESIGN AND METHODS-We used HLA-A*02:01 tetramers complexed to PPI peptides to enumerate circulating PPI-specific CD8(+) T cells in patients and characterize them using membrane markers and single-cell PCR. RESULTS-Most autoreactive CD8(+) T cells detected in recent-onset type 1 diabetic patients are specific for leader sequence peptides, notably PPI6-14, whereas CD8(+) T cells in long-standing patients recognize the B-chain peptide PPI33-42 (B9-18). Both CD8(+) T-cell specificities are predominantly naive, central, and effector memory cells, and their gene expression profile differs from cytomegalovirus-specific CD8(+) T cells. PPI6-14-specific CD8(+) T cells detected in one healthy control displayed Il-10 mRNA expression, which was not observed in diabetic patients. CONCLUSIONS-PPI-specific CD8(+) T cells in type I diabetic patients include central memory and target different epitopes in new-onset versus long-standing disease. Our data support the hypothesis that insulin therapy may contribute to the expansion of autoreactive CD8(+) T cells in the long term. Diabetes 60:32893299, 2011