Evidence for pseudomonas antigen in immune complexes in pseudomonas osteomyelitis

In infections associated with immune complex disease, microbial antigens have rarely been found in the complexes. Using an enzyme‐linked immunoassay, we studied the immune complexes of a patient who had hematogenous Pseudomonas aeruginosa osteomyelitis associated with palpable purpura, arthritis, and microscopic hematuria. After separation of the complexes into high and low molecular weight fractions, a 6hyphen;fold selective concentration of P aeruginosa antibody was found in the low molecular weight fraction compared with the concentration in the serum. Following disruption of immunoglobulin, the high molecular weight fraction competed with solid‐phase P aeruginosa antigen for P aeruginosa antibody from another source. After successful treatment of the infection, the patient's symptoms resolved, and the complexes disappeared. These findings strongly suggest that immune complexes in this patient contained P aeruginosa antigen and antibody that may have been pathogenetic in his disease.