Arthritis associated with intestinal-bypass procedure for morbid obesity. Complement activation and characterization of circulating cryoproteins.

Five patients were studied after intestinal-bypass operations for morbid obesity to determine if the arthritis observed in three of these patients was associated with circulating cryoproteins. Only serum from the three patients with acute arthritis contained cryoprotein complexes. The complexes comprised IgG, IgM, IgA, complement components C3, C4, C5 and IgG antibody against Escherichia coli and Bacillus fragilis. The C3-activator fragment of the properdin complex was identified in fresh serum samples obtained from two of the three patients with circulating cryoprotein complexes and arthritis. These observations suggest that systemically absorbed intestinal bacterial antigens may lead to (or contribute to) the formation of circulating cryoprotein complexes. Circulating cryoprotein complexes activated both the classical and alternate complement pathways and may be important in the pathogenesis of the arthritis associated with the intestinal-bypass procedure for morbid obesity.