Antineutrophil cytoplasmic antibody in patients with primary Sjögren's syndrome.

The incidence, specificity and clinical significance of positivity for serum antineutrophil cytoplasmic antibody (ANCA) was investigated in 60 patients with primary Sjögren's syndrome (SjS). The indirect immunofluorescence (IIF) technique and an enzyme-linked immunosorbent assay (ELISA) were used to measure ANCA. Purified myeloperoxidase (MPO), lactoferrin (LF), cathepsin-G (CTG) and elastase (HLE) served as ANCA antigens for the ELISA. Ten (16.7%) of the 60 SjS patients showed positivity by IIF for perinuclear, but not cytoplasmic, ANCA. Four of the 60 sera were shown to be positive for LF, four for MPO, 0 for CTG and 0 for HLE by ELISA. There was no correlation between ANCA positivity and clinical features. ANCA in patients with SjS might be an epiphenomenon of polyclonal B-cell activation.