EFFECT OF O-ANTIGENIC POLYSACCHARIDE OF ESCHERICHIA-COLI ON ENDOTOXINNEUTRALIZING ACTIVITY OF LYSOZYME

Endotoxemia is considered to be associated with the high mortality of Gram-negative septic patients. Increasing evidence shows that beta-lac tam antibiotics have a propensity to induce endotoxin release from the bacterial outer membrane while killing bacteria. We have recently fou nd that egg white lysozyme (EW-LZM) shows strong inhibition of beta-la ctam induced bacteriolysis and lipopolysaccharide (LPS) release from E scherichia coli O111, resulting in reduction of the LPS-initiated infl ammatory response. In this study, we compared the effect of EW-LZM on E. coli J5, which possesses rough-type LPS (RaLPS), in order to demons trate the effect of O-antigenic polysaccharide on endotoxin neutralizi ng activity of EW-LZM and on inhibition of beta-lactam induced lysis b y LZM. Both of the beta-lactam induced bacterial lysis and subsequent LPS release were almost completely inhibited by EW-LZM. The effect was more potent than that of wild-type LPS as assessed by released LPS co ncentration and LPS induced cytokine syntheses. In addition, EW-LZM wa s effective against lethal infection of E. coli J5 in cyclophosphamide induced leukopenic mice. These facts strongly suggested that O-antige nic polysaccharide negatively modulates LPS neutralizing activity of E W-LZM. (C) 1998 Federation of European Microbiological Societies. Publ ished by Elsevier Science B.V.