Evaluation of protective mAbs against Pseudomonas aeruginosa outer membrane protein I by C1q binding assay

Seven monoclonal antibodies (mAbs) against the outer membrane proteins (OPRs) F, H and I of Pseudomonas aeruginosa were prepared. Western blot analysis has shown the mAbs to cross-react with all 17 serotypes of P. aeruginosa according to the International Antigenic Typing Scheme. Two of the mAbs (2A1, 6A4) protected mice against fatal P. aeruginosa pneumonia. The protective potential of the mAbs did not correlate with the immunoglobulin isotype nor with the fine antigen specificity and the in vitro bactericidal activity of the mAbs. Only the binding of the first complement component C1q of the mAbs as estimated in vitro by an ELISA was significantly correlated with their protective potential.