IgA antibodies against Klebsiella and other Gram-negative bacteria in ankylosing spondylitis and acute anterior uveitis.

Mucosal infections, especially of the gastrointestinal tract, are thought to trigger the onset and/or reactivation of ankylosing spondylitis (AS). Previous investigations into the role of Klebsiella and other Gram-negative bacteria in AS patients show contrasting results. In the present study prevalence of IgA antibodies against Klebsiella, Yersinia, Salmonella, Shigella, and Campylobacter was examined in serum samples from 30 patients having HLA-B27 associated ankylosing spondylitis, 32 patients with HLA-B27 associated acute anterior uveitis (AAU), and 27 HLA-B27 positive patients having both AS and AAU. Numbers of antibodies were compared with those in sera from 29 HLA-B27 negative patients with AAU, 26 healthy HLA-B27 positive and 31 HLA-B27 negative controls. IgA antibodies were detected using an indirect immunofluorescence assay on whole bacteria. In case of Yersinia, Salmonella, Shigella and Campylobacter, reference strains were used. Examination for anti-Klebsiella antibodies was performed using three different strains, isolated from patients with ankylosing spondylitis. The sera were tested on antibodies against Klebsiella K43 (BTS1) as well. The number of IgA positive sera against Yersinia, Salmonella, Shigella, Campylobacter and Klebsiella K43 (BTS1) did not differ between HLA-B27 positive patients and controls, nor among the various groups. Differences were neither observed when the Klebsiella strains from AS patients had been used as antigen. These results do not confirm a relationship between HLA-B27 associated AS or AAU and infection with Klebsiella or other Gram-negative bacteria.