Anti-neutrophil cytoplasm antibodies in patients with giant cell arteritis and/or polymyalgia rheumatica.

Anti-neutrophil cytoplasm antibodies (ANCA) were detected at low titers by indirect immunofluorescence in 1 out of 13 patients with giant cell arteritis (GCA) alone, 7 out of 30 with polymyalgia rheumatica (PMR) alone and 4 out of 15 with GCA plus PMR (8, 23 and 27%, respectively). Anti-myeloperoxidase antibodies were also demonstrated by an enzyme-linked immunosorbent assay in 4 patients with GCA alone (31%), 13 with PRM alone (42%) and 5 with GCA plus PRM (33%). The C-reactive protein response was significantly higher (p < 0.05) in ANCA-positive than in ANCA-negative patients.