Antibodies to Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis in the sera of patients with axial and peripheral form of ankylosing spondylitis.

IgM, IgG and IgA class serum antibodies against the whole Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis bacteria, as well as against K. pneumoniae and E. coli lipopolysaccharides (LPSs) were studied earlier in two separate patient populations of 99 and 85 patients with ankylosing spondylitis (AS) and in 102 healthy blood donors by enzyme immunoassay. In this study the patients were divided into groups according to the presence or absence of peripheral arthritis. The patients with peripheral type AS had increased levels of IgM and IgA class antibodies against K. pneumoniae, whereas the patients with axial type AS had increased levels of IgG and IgA class antibodies to K. pneumoniae, as well as IgA class antibodies against E. coli and P. mirabilis bacteria. Sulphasalazine treatment decreased the IgM and IgA class antibodies in peripheral AS and IgA class antibodies in axial AS against K. pneumoniae LPS. The antibody levels were also decreased against E. coli and P. mirabilis bacteria in the sera of patients with axial AS. The immunological findings in patients with peripheral and axial form of AS were different from each other and thus may reflect different aetiopathogenetic mechanisms for these two types of AS.