Autoimmune Addison's disease--evidence for a role of steroid 21-hydroxylase autoantibodies in adrenal insufficiency.

Autoantibodies to steroid 21-hydroxylase (21-OH) are characteristic of adult onset Addison's disease and we have investigated the effects of these autoantibodies on recombinant human 21-OH enzyme activity. Antibody preparations from 11/11 Addison sera inhibited the ability of 21-OH to convert progesterone to deoxycorticosterone with 8 IgGs showing almost complete inhibition, 2 partial inhibition and 1 weak inhibition. Control IgGs from patients with autoimmune thyroid disease and normal blood donors had little or no effect on 21-OH activity. Our results suggest that 21-OH autoantibodies have the potential to contribute to adrenal failure in Addison's disease by inhibiting the 21-OH enzyme.