Immunoprecipitation of melanogenic enzyme autoantigens with vitiligo sera: evidence for cross-reactive autoantibodies to tyrosinase and tyrosinase-related protein-2 (TRP-2).
In the present study we describe the detection of TRP-2 antibodies in vitiligo patients using in vitro 35S-labelled human TRP-2 in a radioimmunoassay. Of 53 vitiligo sera examined in the assay, three (5 9%) were found to be positive for TRP-2 antibodies. In contrast, 20 control sera, sera from 10 patients with Hashimoto's thyroiditis and sera from 10 patients with Graves' disease were all negative. All three patients positive for TRP-2 antibodies (mean age 54 years, age range 50-63 years) had had vitiligo of the symmetrical type for more than 1 year and all of them also had an associated autoimmune disorder: Graves' disease in one and autoimmune hypothyroidism in two. In addition, antibodies to the melanogenic enzyme tyrosinase were present in their serum. To examine any immunological cross-reactivity between TRP-2 and tyrosinase, the three vitiligo sera positive for TRP-2 antibodies were preabsorbed with COS-7 cell extract containing either expressed TRP-2 or tyrosinase, and subsequently used in the radioimmunoassay. These absorption studies indicated that preincubation with both proteins inhibited the immunoreactivity of the positive sera in the immunoassay using in vitro translated 35S-TRP-2. This antibody cross-reactivity suggests the humoral response to the two melanogenic enzymes in these patients may not be entirely independent.
Kemp
E H
EH
Department of Medicine, University of Sheffield, Clinical Sciences Centre, Northern General Hospital, UK.
Gawkrodger
D J
DJ
Watson
P F
PF
Weetman
A P
AP
D000042:Absorption / Q000276:immunology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D001323:Autoantibodies / Q000032:analysis* / Q000097:blood; D001324:Autoantigens / Q000276:immunology*; D001327:Autoimmune Diseases / Q000097:blood / Q000150:complications / Q000276:immunology; D015551:Autoimmunity; D019556:COS Cells; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003429:Cross Reactions / Q000276:immunology; D005260:Female; D015870:Gene Expression; D006111:Graves Disease / Q000097:blood / Q000276:immunology; D006801:Humans; D019746:Intramolecular Oxidoreductases; D007535:Isomerases / Q000235:genetics / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000276:immunology*; D011233:Precipitin Tests; D011994:Recombinant Proteins / Q000276:immunology; D011995:Recombination, Genetic; D013967:Thyroiditis, Autoimmune / Q000097:blood / Q000276:immunology; D014162:Transfection; D014820:Vitiligo / Q000097:blood / Q000276:immunology*
D001323:Autoantibodies; D001324:Autoantigens; D011994:Recombinant Proteins; D014442:Monophenol Monooxygenase; D007535:Isomerases; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase