Abstract
Autoimmune potyendocrine syndrome type I (Blizzard's syndrome) is an autosomal recessively inherited disease associated with multiple endocrine and non-endocrine manifestations such as autoimmune hypoparathvroidism, adrenalitis, gonadal insufficiency, mucocutaneous candidiasis, alopecia and vitiligo. We have characterised the adrenal autoantigen recognized by autoantibodies in sera from this group of patients. The methods used include indirect immunofluore scenes on frozen sections of different tissues, immunoblotting of adrenal sub-cellular fractions and of proteins expressed in a prokaryotic system and immuno-precipi-ations of labelled lysates of a highly differentiated adrenocortical cell line. In addition, studies on enzyme inhibition were performed. The sera recognized a protein co-migrating in all systems with the rate-limiting enzyme of the steroid biosynthesis, the cholesterol side-chain cleavage enzyme (SCC). Bacterially expressed SCC was recognized by the APS I sera in immunoblotting, whereas no reactivity was found against bacterially expressed 17α-hydroxylase or 21-hydroxylase expressed in a eukaryotic system. SCC-activity in bovine adrenal mitochondria was inhibited by 80% in the presence of APS I sera.
Conclusion: SCC is the autoantigen in APS I. This was shown using a variety of different methods, but is in contrast to a recent report. 21-hydroxylase, the auto-antigen in idiopathic Addison's disease (ref Winqvist O et al., Lancet 1992: 339; 1559-62), is not recognized by APS I sera. These findings illustrate a remarkable specificity in the humoral immune response in the different forms of adrenalitis.
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Winqvist, O., Gustafsson, J., Karisson, F. et al. The adrenal autoantigen in APSI is the side-chain cleavage enzyme. Pediatr Res 33 (Suppl 5), S22 (1993). https://doi.org/10.1203/00006450-199305001-00113
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DOI: https://doi.org/10.1203/00006450-199305001-00113