δ_Pulmonary host defenses. I. Analysis of protein and lipids in bronchial secretions and antibody responses after vaccination with Pseudomonas aeruginosa

The antibody responses in serum and the lower respiratory tract of rabbits immunized with formalized P. aeruginosa culture were examined. After parenteral immunization, IgG agglutinative antibody was present in bronchial secretions, which was probably derived from the intravascular pool of IgG by diffusion into respiratory fluids. After intranasal vaccination, antibody activity was detected in both secretory IgA and the IgG fractions of bronchial secretions; it was considered possible that locally synthesized IgG antibody was elicited. Immune secretory IgA had an inhibitory effect on the growth of lag phase Pseudomonas organisms in addition to its agglutinative activity, both of which were specific for the immunizing serotype. IgG and bronchial secretions did not have this inhibitory effect. IgM and complement components were noticeably absent from bronchial secretions which would indicate that the immune milieu of normal lungs is quite different from that of serum.