Deficiency in B7-H1 (Pd-L1)/pd-1 Coinhibition Triggers Pancreatic Beta-Cell Destruction by Insulin-Specific, Murine Cd8 T-Cells

OBJECTIVE-RIP-B7.1 mice expressing the costimulator molecule B7 1 (CD80) on pancreatic beta-cells are a well established model to characterize preproinsulin-specific CD8 T-cell responses and experimental autoimmune diabetes (EAD) Different immunization strategies could prime preproinsulin-specific CD8 T-cells in wild-type C57BL/6 (B6) mice, but did not induce diabetes. We tested whether altering the B7-H1 (PD-L1) coinhibition on pancreatic beta-cells can reveal a diabetogenic potential of preproinsulin-specific CD8 T-cells.RESEARCH DESIGN AND METHODS-DNA-based immunization and adoptive T-cell transfers were used to characterize the induction of preproinsulin-specific CD8 T-cell responses and EAD in RIP-B7 1, B6, B7-H1(-/-), PD-1(-/-) or bone marrow chimeric mice.RESULTS-Preproinsulin-specific CD8 T-cells primed in B6 mice revealed their diabetogenic potential after adoptive transfer into congenic RIP-B7 1 hosts. Furthermore, preproinsulin-specific CD8 T-cells primed in anti-B7-H1 antibody-treated B6 mice, or primed in B7-H1(-/-) or PD-1(-/-) mice induced EAD. Immunization of bone marrow chimeric mice showed that deficiency of either B7-H.1 in pancreatic beta-cells or of PD-1 in autoreactive CD8 T-cells induced EAD.CONCLUSIONS-An imbalance between costimulator (B7.1) and coinhibitor (B7-H1) signals on pancreatic beta-cells can trigger pancreatic beta-cell-destruction by preproinsulin-specific CD8 T-cells. Hence, regulation of the susceptibility of the beta-cells for a preproinsulin-specific CD8 T-cell attack can allow or suppress EAD. Diabetes 59:1966-1973, 2010