ANTIBODY-RESPONSES TO GUT BACTERIA IN ANKYLOSING-SPONDYLITIS, RHEUMATOID-ARTHRITIS, CROHNS-DISEASE AND ULCERATIVE-COLITIS

Specific immunoreactive anti-Klebsiella antibodies are found in patien ts with ankylosing spondylitis (AS), a significant proportion of whom have occult inflammatory bowel disease. Molecular mimicry between Kleb siella or other bacterial antigens and HLA-B27 has been suggested in t he pathogenesis of AS. The specificity of increased immunoreactivity a gainst Klebsiella remains to be assessed against the abundant anaerobi c bacterial flora, present either in healthy controls or in patients w ith ulcerative colitis (UC) and Crohn's disease (CD). Total immunoglob ulin (Ig; IgG, IgA, IgM) immunoreactivity was measured by ELISA agains t Klebsiella pneumoniae, Proteus mirabilis, Escherichia coli and ten a naerobic isolates of the predominant normal bowel flora in 35 patients with active AS, 60 patients with inflammatory bowel disease (30 CD, 3 0 UC), 60 patients with active rheumatoid arthritis (RA) and 60 health y controls. Ig immunoreactivity to K. pneumoniae was significantly ele vated in AS (P < 0.001), CD (P < 0.001) and UC (P < 0.001) patients co mpared with RA patients and healthy controls. Furthermore, Ig immunore activity to P. mirabilis was significantly elevated only in RA patient s, compared with the other inflammatory groups (P < 0.001) and control s (P < 0.001). There was no significant antibody response against E. c oli or the ten obligate anaerobes in any of the test groups. The data suggested an increased immune response to Klebsiella in patients with AS, UC, CD and to Proteus in patients with RA. The specificity of thes e responses in some patients supported a possible role for enteric Kle bsiella in the pathogenesis of AS and Proteus in RA. The role of Klebs iella in inflammatory bowel disease requires further study.