DETECTION OF ADRENOCORTICAL AUTOANTIBODIES IN ADDISONS-DISEASE WITH APEROXIDASE-LABELED PROTEIN-A TECHNIQUE

Adrenocortical autoantibodies (ACA), present in 60-80% of patients wit h idiopathic Addison's disease, are conventionally detected by indirec t immunofluorescence (IIF) on frozen: sections of adrenal glands. The large-scale use of IIF is limited in part by the need for a fluorescen ce microscope and the fact that histological sections cannot be stored for long periods of time. To circumvent these restrictions we develop ed a novel peroxidase-labelled protein A (PLPA) technique for the dete ction of ACA in patients with Addison's disease and compared the resul ts with those obtained with the classical IIF assay. We studied serum samples from 90 healthy control subjects and 22 patients with Addison' s disease, who had been clinically classified into two groups: idiopat hic (N = 13) and granulomatous (N = 9). ACA-PLPA were detected in 10/2 2 (45%) patients: 9/13 (69%) with the idiopathic form and 1/9 (11%) wi th the granulomatous form, whereas ACA-IIF were detected in 11/22 pati ents (50%): 10/13 (77%) with the idiopathic form and 1/9 (11%) with th e granulomatous form. Twelve of the 13 idiopathic addisonians (92%) we re positive for either ACA-PLPA or ACA-IIF, but only 7 were positive b y both methods. Ta contrast, none of 90 healthy subjects was found to be positive for ACA. Thus, our study shows that the PLPA-based techniq ue is useful, has technical advantages over the IIF method (by not req uiring the use of a fluorescence microscope and by permitting section storage for long periods of time). However, since it is only 60% conco rdant with the ACA-IIF method, it should be considered complementary i nstead of an alternative method to IIF for the detection of ACA in hum an sera.