Diabetes progression in age-matched naive and conditioned NOD mice that did/did not receive transplants. Chimeras were prepared using anti-CD8 mAb preconditioning or anti-CD8 mAb plus anti-CD154 plus TBI. The progression to diabetes was monitored in control mice and mice given TBI conditioning doses in the absence and presence of mAb treatments. For all treatment groups, the presence of chimerism was associated with protection from diabetes.