Autoantibodies against recombinant human steroidogenic enzymes 21-hydroxylase, side-chain cleavage and 17 alpha-hydroxylase in Addison's disease and autoimmune polyendocrine syndrome type III

Objective: To evaluate the frequency of autoantibodies (Ab) against 21 hydr oxylase (210H), side-chain cleavage (SCC) and 17 alpha-hydroxglase (17OH), in Addison's disease (AD) and autoimmune polyendocrine syndrome type III (A PSIII), Design and Methods: We used radiobinding assays and in vitro transl ated recombinant human S-35-21OH, S-35-SCC or S-35-17OH and studied serum s amples from 29 AD (18 idiopathic, 11 granulomatous) and 18 APSIII (autoimmu ne thyroid disease plus type 1 diabetes mellitus, without AD) patients. Res ults were compared with those of adrenocortical autoantibodies obtained wit h indirect immunofluorescence (ACA-IIF). Results: ACA-IIF were detected in 15/18 (83%) idiopathic and in 1/11 (9%) granulomatous AD subjects. 21OHAb w ere found in 14/18 (78%) idiopathic and in the same (9%) granulomatous AD s ubject. A significant positive correlation was shown between ACA-IIF and 21 OHAb levels (r(2) = 0.56, P < 0.02). The concordance rate between the two a ssays was 83% (24/29) in AD patients. SCCAb were found in 5/15 (28%) idiopa thic (4 of whom were also positive for 21OHAb) and in the same (9%) granulo matous AD subject, 170HAb were found in only 2/18 (11%) idiopathic and none of the granulomatous AD patients. Two APSIII patients were positive for AC A-IIE but only one was positive for 210HAb and SCCAb. 170HAb were found in another two APSIII patients. Conclusions: Measurement of 210HAb should be t he first step in immune assessment of patients with AD and individuals at r isk for adrenal autoimmunity, in addition to ACA-IIF. Due to their low prev alence in AD, measurement of SCCAb and 170HAb should be indicated only for 210HAb negative patients and/or for those with premature ovarian failure, r egardless of ACA-IIF results.