DETECTION OF TYROSINASE AUTOANTIBODIES IN PATIENTS WITH VITILIGO USING S-35 LABELED RECOMBINANT HUMAN TYROSINASE IN A RADIOIMMUNOASSAY

Tyrosinase antibodies recently have been reported to occur frequently in patients with vitiligo, We describe the detection of tyrosinase ant ibodies in vitiligo patients using in vitro S-35-labeled human tyrosin ase in a radioimmunoassay. Of 46 vitiligo sera examined in the assay, five (10.9%) were found to be positive for tyrosinase antibodies, In c ontrast, 20 control sera and sera from 10 patients with Mashimoto's th yroiditis were negative, Four of the sera positive in the radioimmunoa ssay were also positive in an ELISA using mushroom tyrosinase as antig en. Absorption studies indicated that pre-incubation with mushroom tyr osinase absorbed out the immunoreactivity of the positive sera in the radioimmunoassay, suggesting cross-reactivity, but this absorption was never complete, indicating that there are tyrosinase antibodies in hu man sera that do not react with the mushroom protein. There was no obv ious association between the presence of tyrosinase antibodies and the age of the patients (range: 22-62 y), their duration of disease (rang e: 5-20 y), or the type of vitiligo (one segmental, one symmetrical/pe riorificial, three symmetrical), although the three patients with the highest antibody levels also had an associated autoimmune disorder (on e with Graves' disease; two with autoimmune hypothyroidism). The resul ts confirm that tyrosinase autoantibodies are present in the sera of v itiligo patients but at a low frequency. The technique described is se nsitive and quantitative and allows the detection of conformational ep itopes, It will be useful in longitudinal studies to determine the rel ation between the clinical features of vitiligo and tyrosinase antibod y levels.