EFFECT OF HIGH-AFFINITY ANTIPSEUDOMONAS AERUGINOSA LIPOPOLYSACCHARIDEANTIBODIES INDUCED IMMUNIZATION ON THE RATE OF PSEUDOMONAS-AERUGINOSAINFECTION IN PATIENTS WITH CYSTIC-FIBROSIS

Patients with cystic fibrosis (CF; N = 26) and with no prior history o f infection with Pseudomonas aeruginosa were immunized with an octaval ent O-polysaccharide-toxin A conjugate vaccine. During the next 4 year s, 16 patients (61.5%) remained free of infection and 10 (38.5%) becam e infected, Total serum antilipopolysaccharide (LPS) antibody levels i nduced by immunization were comparable in infected and noninfected pat ients. In contrast, 12 of 16 noninfected versus 3 of 10 infected patie nts (p = 0.024) mounted and maintained a high-affinity anti-LPS antibo dy response. When compared retrospectively with the rate in a group of age- and gender-matched, nonimmunized, noncolonized patients with CF, the rate at which P. aeruginosa infections were acquired was signific antly lower (p less than or equal to 0.02) among all immunized versus nonimmunized patients during the first 2 years of observation. Subsequ ently, only those immunized patients who maintained a high-affinity an ti-LPS antibody response had a significant reduction (p less than or e qual to 0.014) in the rate of infection during years 3 and 4. Smooth, typeable strains of P. aeruginosa predominated among immunized patient s; rough, nontypeable strains were most frequently isolated from nonim munized patients. Mucoid variants were isolated from one immunized pat ient versus six nonimmunized patients. These results. indicate that th e induction of a high-affinity P. aeruginosa anti-LPS antibody respons e can influence the rate of infection in patients with CF.