Ten days post-implantation, a time at which recurrent diabetes is first detected, TCR Vβ usage by CD4+ and CD8+ naïve and Teff/mem was examined in the islet graft, the renal lymph node (RLN) draining the graft site, pancreas, pancreatic lymph node (PLN), and spleen of individual recipients. This evidence concerns the gene CD8A and diabetes mellitus.