Antibody response in patients with Pseudomonas aeruginosa infection to a 'common antigen' from P. aeruginosa analysed by means of quantitative immunoelectrophoretic methods

381 sera from 101 patients suffering from Pseudomonas aeruginosa infection have been investigated for antibodies against a 'common antigen' (CA) and other antigens from P. aeruginosa by means of crossed immunoelectrophoresis with intermediate gel, using a polyspecific P. aeruginosa antigen/antibody reference system. The earliest antibody response during the P. aeruginosa infections included increased CA antibodies in only 38% of the patients examined. The peak level of the antibody response included increased CA antibodies in 71% of the patients. By means of 'absorption of antibodies in situ', it was found that the antibody response to CA was directed against both the common cross-reactive part of the CA molecule and the Pseudomonas-specific part, with individual variations. During infections caused by other bacteria containing CA, one-third of the patients developed antibodies against CA. The diagnostic implications of the results are discussed.