Immunoglobulin G antineutrophil cytoplasmic antibodies are produced in the respiratory tract of patients with Wegener's granulomatosis.

Wegener's granulomatosis (WG) is a small-vessel vasculitis of unknown etiology that usually involves the upper and lower respiratory tract and the kidneys. Recently, an association has been made between the presence of serum antineutrophil cytoplasmic antibodies (ANCA) and WG. Because WG frequently involves the lung, we sought to evaluate bronchoalveolar lavage (BAL) fluids obtained from 14 patients with WG for the presence of ANCA. Immunoglobulin (Ig) G ANCA was found in the BAL with the same staining patterns as observed in the serum. Patients with active disease had the highest serum and BAL IgG ANCA titers. IgA or IgM ANCA was not detected in the serum or BAL of these patients. Protein analysis of BAL fluid revealed that patients with active, untreated WG had approximately a fourfold elevation in total protein (41.3 versus 10.5 mg/dl), with a disproportionately greater increase in the ratio of IgG to albumin (BAL IgG index = 1.49, normal = 0.74; p = 0.027). The increase of the IgG index in patients with active WG suggests that local production of IgG ANCA occurs in the lungs.