Activity of intravenous immune globulins against Klebsiella

Seven commercial intravenous immune globulin (IVIG) preparations and an experimental hyperimmune globulin (Klebsiella immune-IVIG) were analyzed for antibody levels to Klebsiella capsular polysaccharides, opsonic activity, and protective capacity against Klebsiella. With one exception, all IVIGs reacted immunologically with the various capsular antigens, although titers between the preparations varied considerably. Klebsiella immune-IVIG possessed substantially higher titers (32-fold to 128-fold) than the commercial preparations. Only the hyperimmune globulin was capable of promoting the phagocytosis and killing of six Klebsiella test strains. When prophylactically administered, a commercial IVIG afforded significant protection (P less than 0.01) against fatal experimental Klebsiella sepsis only at a dose of 500 mg/kg. Klebsiella immune-IVIG provided a similar level of protection at a dose of 5 mg/kg. Whereas the commercial IVIG was ineffective when used therapeutically, the hyperimmune globulin was highly protective. Combined antibiotic-immunoglobulin therapy was most effective at reducing mortality.