IgA antibodies in HLA-B27 associated acute anterior uveitis and ankylosing spondylitis.

Acute anterior uveitis (AAU) and ankylosing spondylitis (AS) are, like reactive arthritis (ReA), strongly associated with HLA-B27. Mucosal infections play a role in the pathogenesis of ReA. To investigate whether these microorganisms are also involved in the pathogenesis of AAU and AS, we examined blood samples from patients with AAU, AS or both, and healthy controls for presence of antibodies against Klebsiella pneumoniae (K 30), Salmonella enteritidis and S. typhimurium, Chlamydia trachomatis, Proteus mirabilis and Borrelia burgdorferi. The IgA, IgG and IgM classes of these antibodies were measured using an enzyme-linked immunosorbent assay. No significant differences were found in the frequency in which these antibodies occurred in HLA-B27 positive patients with AAU or AS and healthy controls. However, IgA antibodies against K. pneumoniae (p < 0.01) and IgA and IgG antibodies against P. mirabilis (p < 0.01 and p < 0.05) were detected more frequently in HLA-B27 negative patients with AAU than in healthy controls. The results of this study are in contrast with various earlier reports in which antibodies against Klebsiella strains were more frequently found in patients with HLA-B27 associated ankylosing spondylitis than in healthy controls.