Efficacy of human gamma-globulin preparation in experimental pseudomonas aeruginosa infections in mice and its mode of action.

The agglutinin titer of S-sulfonated human gamma-globulin (GGS, Venilon) against the formalinized cells of 20 clinical isolates of P. aeruginosa distributed as follows: 1:128 to 1:512 in 6 strains, 1:32 to 1:64 in 13 strains and 1:16 in only 1 strain. GGS given passively protected mice against P. aeruginosa infection, however, the effect of GGS differed markedly among the strains used. The difference in the effect was in correlation with the agglutinin titer of GGS against the formalinized cells but not in correlation with that against the heat-killed cells, serotypes or elastase- or protease-producing abilities of P. aeruginosa. In the experiment with representative GGS-sensitive P. aeruginosa No. 97 and GGS-resistant P. aeruginosa No. 20, P. aeruginosa No. 97 was drastically killed by polymorphonuclear leukocytes (PMNs) and macrophages in the presence of GGS, but P. aeruginosa No. 20 remained entirely unaffected. P. aeruginosa No. 97 preopsonized with GGS became more sensitive to phagocytic killing by PMNs and in vivo bactericidal activity than non-treated P. aeruginosa No. 97. Preopsonized P. aeruginosa No. 97 also markedly decreased its virulence in mice. Absorption of GGS with the formalinized P. aeruginosa No. 97 cells simultaneously reduced the agglutinating activity, protective capacity and in vivo bactericidal activity. These results indicate that the protective effect of GGS against pseudomonal infection in mice depended on an amount of specific antibody to heat-labile antigens of each P. aeruginosa used.