Abstract: Objective To investigate the role of CD8+T cells in the pathogenesis of diabetes.Methods CD4+T cells and CD8+T cells were respectively transferred from genetically-engineered non-obese diabetic(NOD)mice and NOD background mice to T cell-deficient NOD mice(i.e.NOD.scid mice)and T cell-deficient NOD mice with co-stimulating molecules CD80 expressed specific on islets B cells(i.e.NOD.scid.Rip.B7 mice).Insulitis and diabetes were monitored in the two recipients and the difference between the two recipients was analyzed.Results There was no significant difference in incidence of diabetes between recipients of NOD.scid mice and NOD.scid.R ip.B7 mice when CD4+T cells were transfer red (P>0.05).However,when CD8+T cells were transfer red,the incidence of diabetes in NOD.scid recipients was significantly lower than that of in NOD.scid.Rip.B7 recipients(P<0.001).Conclusion CD8+T cells triggers the infiltration of the pancreatic islets,CD8+T cells initiate diabetes by direct interaction with islet beta cells.