Specific Pulmonary Defences against Pseudomonas aeruginosa after Local Immunization with Temperature-sensitive Mutants

The specificity of the enhancement in lung defences after local immunization of mice with three temperature-sensitive (ts) mutants of Pseudomonas aeruginosa was investigated. The three selected mutants display altered growth characteristics when transferred from 29 degrees C to mammalian body temperature. Mice immunized with the live ts mutants by aerosol exposure or multiple intranasal inoculations were challenged with aerosols containing wild-type (wt) P. aeruginosa. Aerosol immunization with ts mutant A/10/25 significantly enhanced the lung clearance of the wt but did not enhance the clearance of either Klebsiella pneumoniae or Staphylococcus aureus. Aerosol immunization with ts mutants D/1/8 or E/9/9 enhanced the lung defences against the parental wt (of identical immunotype 1) but not against immunotype 4; similarly, intranasal immunization enhanced the lung defences against the parental wt but not against immunotypes 4 or 5. We conclude that local immunization with ts mutants of P. aeruginosa enhances lung defences against the wt in a genus- and immunotype-specific fashion. It is suggested that local immunity may play a central role in immunoprophylaxis against P. aeruginosa lung infection.