Comparison of anti-PR3 capture and anti-PR3 direct ELISA for detection of antineutrophil cytoplasmic antibodies (ANCA) in long-term clinical follow-up of PR3-ANCA-associated vasculitis patients

A total of 118 sera from 11 patients with anti-neutrophil cytoplasmic antib odies against proteinase-3- (PR3-ANCA) associated vasculitis were retrospec tively screened by anti-PR3 capture and anti-PR3 direct ELISA tests. We stu died the relationship between capture and direct ELISA scores and the clini cal activity of PR3-ANCA-associated vasculitis patients during follow-up. W e also studied the ability of the anti-PR3 capture ELISA to detect positive values of PR3-ANCA in clinical vasculitis relapses. Only capture ELISA pre sented a significant relationship (p < 0.05) with clinical activity of PR3- ANCA-associated vasculitis patients over time. Capture ELISA appears to be a reliable method for detecting clinical relapses in this group of patients . Our results indicate that the new capture ELISA test is more effective th an direct ELISA in the follow-up of patients with PR3-ANCA-associated vascu litis and in the detection of relapses.