Protection of immunosuppressed mice against infection with pseudomonas aeruginosa by monoclonal antibodies to outer membrane protein OprI.

Two monoclonal antibodies (mAbs) designated 2A1 and 6A4 which had been shown to be directed against Pseudomonas aeruginosa outer membrane lipoprotein I were tested in cyclophosphamide treated mice for their protective ability against P. aeruginosa infection. Pretreatment of mice with either 2 mg of 2A1 or 4 mg of 6A4 in combination with lethally irradiated human leucocytes reduced the mortality after subsequent subcutaneous injection of 100 living P. aeruginosa organisms to 50% of the controls. Without leucocytes only mAb 2A1 (isotype IgG2b) showed protection (47%). Irradiated leucocytes alone without mAb did not protect the mice significantly from fatal P. aeruginosa infection.