Granulocyte colony-stimulating factor enhances protection by anti-K1 capsular IgM antibody in murine Escherichia coli sepsis.

ABSTRACT

Combined prophylactic treatment with recombinant murine granulocyte colony-stimulating factor (G-CSF) and a suboptimal dose of anti-K1 capsular IgM monoclonal antibody (MAb) significantly enhanced survival in an experimental mouse Escherichia coli O7K1 peritonitis model compared with untreated animals (67% vs. 11% survival; P < 0.001) and with either treatment alone (67 vs. 29% and 27% survival, respectively; P < 0.01), which suggests synergism between these agents. Enhanced survival by combined treatment was associated with increased neutrophil counts in blood and peritoneal lavage fluid, lower systemic and higher levels of local tumour necrosis factor (TNF) and lower bacterial counts in blood cultures. Mouse neutrophils treated with G-CSF but not infected with E. coli showed enhanced phagocytic and respiratory burst capacity, down-regulation of L-selectin receptors and enhanced expression of Fc RII-III receptors but not of complement receptors.