We reported that adoptively transferred OVA-specific transgenic OTI (CD8) T cells and OTII (CD4) T cells, as well as other host cells, co-operatively produce the endoglycosidase heparanase-1 (HPSE-1) to enable migration of the OT T cells to host islets, the subsequent damage of OVA-expressing beta cells, and the acute induction of T1D within 2 weeks after cell transfer [12]. This evidence concerns the gene CD8A and type 1 diabetes mellitus.