Thyroid lesions were also significantly more severe in anti-B7-1-treated NOD-B7-2KO-H-2h4 mice compared to anti-B7-1-treated NOD-B7-2KO mice, in agreement with the strong contribution of H-2h4 elements to the development of autoimmune thyroiditis on the NOD background. Here, CD80 is linked to autoimmune thyroid disease.