SAFETY AND IMMUNOGENICITY OF KLEBSIELLA-PNEUMONIAE K1 CAPSULAR POLYSACCHARIDE VACCINE IN HUMANS

The safety and immunogenicity of 2 K. pneumoniae K1 capsular polysaccharide (CPS) vaccines were evaluated in humans. Trace quantities of lipopolysaccharide present in vaccine preparations were detoxified by treatment of K1 CPS in a 95% ethanol-0.1 N NaOH solution. This procedure greatly reduced the pyrogenicity of K1 CPS but did not markedly alter its antigenicity, MW or immunogenicity for animals. Volunteers received either 25 or 50 .mu.g of untreated or NaOH-treated K1 CPS vaccine s.c. Systemic reactions on primary vaccination were infrequent with both vaccine preparations. The frequency and severity of local reactions were substantially reduced after immunization with NaOH-treated vaccine as compared with untreated K1 CPS. All vaccines responded with a .gtoreq. 4-fold rise in IgG and IgM titers. IgG antibody to K1 CPS isolated from immune sera was highly effective in preventing fatal experimental burn wound sepsis due to K. pneumoniae K1 in mice.