Selective activation of classical and alternative pathways of human complement by "promptly serum-sensitive" and "delayed serum-sensitive" strains of Serratia marcescens

Abstract

Chelation of fresh human serum with 0.01 M MgCl2 (Mg) plus 0.01 M ethylene glycol tetraacetic acid failed to abrogate the bactericidal activity against "delayed serum-sensitive" strains of Serratia marcescens, whereas previously "promptly serum-sensitive" strains of S. marcescens and control strain Escherichia coli C were killed after an extended period of incubation. The addition of 0.01 M ethylenediametetracetate to fresh human serum neutralized bactericidal activity against S. marcescens of either serum sensitivity category.