Antibodies against bacterial lipopolysaccharides in Japanese patients with ankylosing spondylitis.

We investigated IgG, IgA and IgM class specific antibodies to five bacterial (Klebsiella pneumoniae, Escherichia coli, Salmonella enteritidis, Salmonella typhimurium and Shigella flexneri) lipopolysaccharides (LPS) by enzyme-linked immunosorbent assay in 144 Japanese patients with ankylosing spondylitis (AS). AS patients had significantly elevated IgA antibodies to K. pneumoniae LPS, Salmonella enteritidis LPS and Salmonella typhimurium LPS; however, there was no correlation between antibody level to LPS and acute-phase reactants, erythrocyte sedimentation rate and serum C-reactive protein.