Seroprevalence of Helicobacter pylori infection in patients with connective tissue diseases.

To assess the possibility that Helicobacter pylori might be an etiologic agent, titers of anti-H. pylori IgG in sera of patients with connective tissue diseases [rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), polymyositis or dermatomyositis (PM/DM), progressive systemic sclerosis (PSS), mixed connective tissue disease (MCTD) and Sjögren's syndrome (SjS)] were compared with those of non-patient (healthy) volunteers and of patients with chronic pulmonary diseases (CPD) by ELISA using an extract of sonicated H. pylori as the antigen. Among patients with connective tissue diseases, those with SLE and RA had anti-H. pylori titers as low as healthy volunteers. Patients with SjS had much higher average titers than patients with CPD (P < 0.05). We previously reported that levels of myeloid calcium-binding protein (MRP8 and MRP14) were elevated in the serum of patients with connective tissue diseases. No correlation was found between serum levels of anti-H. pylori IgG and of MRP, a novel marker of inflammation. Furthermore, sera with high IgG titers were selected, and their reactivity with the H. pylori antigen were analyzed by Western blotting. H. pylori antigens with a variety of molecular masses were immunostained with sera from patients and from healthy volunteers, but a 16-kDa antigen was only immunostained by reaction with the sera of patients with MCTD and SjS, although the number of test samples was small.