The role of endogenous B7-H3 in the pathogenesis and progression of autoimmune disease has been evaluated by various laboratories using both monoclonal antibodies (mAb) and B7-H3 deficient mice (KO), but the results are somewhat contradictory with both costimulatory and coinhibitory effects being described in various model systems [8–9]. This evidence concerns the gene CD276 and autoimmune disease.