Bactericidal-activities of human polymorphonuclear leukocyte proteins against Escherichia coli O111:B4 coated with C5 or C8

Abstract

The postnuclear supernatant of disrupted polymorphonuclear leukocytes exhibited bactericidal activity on Escherichia coli O111:B4 coated with immunoglobulin M antibodies and C5 or C8 but not on C3- or C7-coated bacteria. To characterize this antimicrobial activity further, granules obtained from the postnuclear supernatant were extracted with sodium acetate (pH 4) and the soluble extract was subsequently fractionated through carboxymethyl cellulose and Sephacryl S-200. Over 90% of the activity present in the starting material was recovered in the soluble granule extract. Kinetic and dose-response analyses of the bacterial activity of the polymorphonuclear leukocyte extract on BAC1-5 and BAC1-8 revealed different susceptibilities to killing of these two bacterial intermediates; they also differed for their susceptibilities to killing at 37 degrees C and at room temperature. The suggestion raised by these data, that BAC1-5 and BAC1-8 could be killed by different bactericidal factors, was confirmed by the findings that separate fractions of the soluble granule extract obtained by carboxymethyl cellulose and Sephacryl S-200 chromatography exhibited specific activity on either BAC1-5 or BAC1-8, whereas other fractions were active on both intermediates.