To determine the occurrence of antineutrophil cytoplasmic antibodies (ANCA) and the specificity of these antibodies (Ab) in serum from patients with rheumatoid arthritis (RA) and patients with rheumatoid arthritis complicated by vasculitis (rheumatoid vasculitis [RV]).
ANCA was detected with an indirect immunofluorescence test on ethanol-fixed granulocytes. Ab against the cytoplasmic antigens proteinase-3, elastase, lactoferrin (LF), and myeloperoxidase were measured by enzyme-linked immunosorbent assay.
ANCA were found in the serum of 43% of 49 patients with RV and in 36% of 50 patients with RA. Anti-LF Ab occurred more frequently in RV patients (45%) than in RA patients (4%), whereas reactivity against the other cytoplasmic antigens did not differe significantly between these groups.
Anti-LF Ab in serum of patients with RA may be useful in the diagnosis of vasculitis in RA.