Anti-neutrophil cytoplasmic antibodies in giant cell arteritis and polymyalgia rheumatica.

Antineutrophil cytoplasmic antibodies (ANCA) were demonstrated in all sera from 11 patients with active giant cell arteritis (GCA) using indirect immunofluorescence on 9% paraformaldehyde(PF)-fixed neutrophils according to Pryzwanski (median titer 1:256, range 1:64 to 1:512). After treatment during inactive disease titers decreased in all sera. Eight out of 9 sera from patients with active polymyalgia rheumatica (PMR) produced a cytoplasmic staining on Pryzwanski-fixed neutrophils in low titers (median titer 1:16, range 0 to 1:32), as did 8 out of 25 sera from healthy blood donors. None of the sera were positive for antibodies to defined antigens, i.e. proteinase-3, human leucocyte elastase, myeloperoxidase and lactoferrin as detected by ELISA. GCA seems to be associated with ANCA of as yet unknown specificity.