AFFINITY-PURIFIED ESCHERICHIA-COLI J5 LIPOPOLYSACCHARIDE-SPECIFIC IGGPROTECTS NEUTROPENIC RATS AGAINST GRAM-NEGATIVE BACTERIAL SEPSIS

Antibodies were raised in rabbits by immunization with the heat-killed J5 mutant of Escherichia coli O111 (Re chemotype). Serum antibodies w ere separated into purified IgG and IgM by sequential affinity chromat ography on protein G-Sepharose and anti-rabbit IgG-Sepharose columns. J5 lipopolysaccharide (LPS)-specific IgG was prepared by affinity chro matography of purified Ige on a J5 LPS-EAH Sepharose 4B affinity colum n. Purified IgM, IgG, and J5 LPS-specific IgG protected neutropenic ra ts against lethal challenge with Pseudomonas aeruginosa 12:4:4 (Fisher Devlin immunotype 6). Nine of 16 rats treated with the IgM fraction w ere protected (P < .001). Thirteen of 20 rats treated with the purifie d IgG and 6 of 8 treated with J5 LPS-specific IBG were protected compa red with none of 25 treated with IgG made from the preimmune serum of the same rabbit (P < .001). These results demonstrate that purified J5 LPS-specific IgG protects against the lethal consequences of gram-neg ative bacteremia.