PURPOSE: Certain uveitis patients express the disease-marker antibody pANCA. Histone H1 (H1) and mycobacterial HupB (HupB) are recently identified candidate pANCA antigens. This study addresses the hypothesis that H1 and HupB are targets of disease-associated seroreactivity in pANCA+ uveitis. METHODS: Sera from 293 uveitis patients were categorized for pANCA activity. H1(69-171) and HupB recombinant proteins were used as antigenic targets in ELISA studies. Selected sera were analyzed for reactivity by Western blot. RESULTS: Seroreactivities to ANCA, H1(69-171), and HupB were frequently detected in uveitis patients. No significant relationship existed between the level of ANCA antibody and reactivity to either recombinant antigen. There was, however, a significant, positive correlation between H1(69-171) and HupB seroreactivities. CONCLUSIONS: Correlation between H1(69-171) and HupB reactivities suggests the presence of a shared dominant epitope, which is recognized by antibodies in a substantial number of uveitis patients. Seroreactivities to ANCA and HupB/H1 are independent immunologic markers that may identify biologically distinctive subsets of uveitis.
PURPOSE: Certain uveitispatients express the disease-marker antibody pANCA. Histone H1 (H1) and mycobacterial HupB (HupB) are recently identified candidate pANCA antigens. This study addresses the hypothesis that H1 and HupB are targets of disease-associated seroreactivity in pANCA+ uveitis. METHODS: Sera from 293 uveitispatients were categorized for pANCA activity. H1(69-171) and HupB recombinant proteins were used as antigenic targets in ELISA studies. Selected sera were analyzed for reactivity by Western blot. RESULTS: Seroreactivities to ANCA, H1(69-171), and HupB were frequently detected in uveitispatients. No significant relationship existed between the level of ANCA antibody and reactivity to either recombinant antigen. There was, however, a significant, positive correlation between H1(69-171) and HupB seroreactivities. CONCLUSIONS: Correlation between H1(69-171) and HupB reactivities suggests the presence of a shared dominant epitope, which is recognized by antibodies in a substantial number of uveitispatients. Seroreactivities to ANCA and HupB/H1 are independent immunologic markers that may identify biologically distinctive subsets of uveitis.