INHIBITION OF BACTERIAL MOTILITY WITH HUMAN ANTIFLAGELLAR MONOCLONAL-ANTIBODIES ATTENUATES PSEUDOMONAS AERUGINOSA-INDUCED PNEUMONIA IN THE IMMUNOCOMPETENT RAT

Two human monoclonal antibodies, directed against the type a and type b flagellar proteins of Pseudomonas aeruginosa, inhibited bacterial mo tility in vitro specifically and in a concentration-dependent manner. In order to determine if this decreased bacterial motility was associa ted with a decreased pathogenicity, the ability of these human antifla gellar monoclonal antibodies to attenuate P. aeruginosa-induced pneumo nia in the rat was assessed. Incubation of P. aeruginosa with a 1:1 mi xture of the human antiflagellar monoclonal antibodies prior to pulmon ary instillation significantly (P < 0.05) ameliorated the bacterium-in duced decrease in arterial blood oxygen pressure, blunted the increase in respiratory rate, and markedly reduced the area of pulmonary infla mmation. Similarly, intravenous administration of the human antiflagel lar monoclonal antibodies 1 h after pulmonary instillation of the bact eria also reduced the in vivo pathogenicity of P. aeruginosa. Therefor e, human antiflagellar monoclonal antibodies can decrease the in vitro motility of P. aeruginosa and can reduce its in vivo pathogenicity wh en administered either before or after bacterial challenge.