Antineutrophil cytoplasmic antibodies (ANCAs) occur in vasculitides, including Wegener's granulomatosis and Churg-Strauss syndrome. Their presence in sera of patients with some other rheumatic diseases has been well documented. ANCAs have also been detected in synovial fluid (SF) of patients with RA; however, their presence and potential role in early stages of the disease is not known.
The aim of the study was to evaluate the prevalence and specificity of ANCAs in SF in early RA.
SF samples were obtained from 114 patients with early RA. Control SF were taken from 76 patients with knee osteoarthritis (OA). ANCAs were detected by indirect immunofluorescence and by ELISA. Proteinase 3, myeloperoxidase, elastase, lactoferrin and lysozyme, as well as cathepsin G, were used as antigens in ELISA method. At the same time antinuclear antibodies (ANAs) and rheumatoid factor (RA) were detected in SF samples under study.
ANCAs were found by indirect immunofluorescence in SF of 26/114 (22.8%) patients with early RA and 2/76 (2.6%) patients with OA. A perinuclear pattern (p-ANCA) was detected in 22/26 cases (84.6%), and atypical pattern (a-ANCA) in 4/26 (15.3%). In patients with OA, p-ANCAs only were observed. We did not observe a cytoplasmic pattern (c-ANCA) in indirect immunofluorescence or in the reactivity against proteinase 3 in ELISA. p-ANCAs yielded reactivity against lactoferrin in SF from 15/26 (57%) and against myeloperoxidase in 5/26 (19.2%) SF samples from RA patients. a-ANCAs indicated reactivity against cathepsin G in 3/26 cases (11.5%) and against lysozyme in 1/26 (3.8%). RF was present in 18/26 (69.2%) and ANA in 14/114 (12.2%) SF samples from patients with RA.
ANCAs are present in SF of over 20% of patients with early RA We think that these antibodies in SF could be one of the early RA markers. Their role in this stage of synovitis should be clarified.