Correlation between phagocytic activity and metabolic response of polymorphonuclear leukocytes toward different strains of Escherichia coli.

The bactericidal activity, the phagocytic capacity, and the metabolic stimulation of polymorphonuclear leukocytes challenged with different strains of Escherichia coli were studied. It was found that only two strains out of 10 tested stimulated the oxygen consumption and carbohydrate metabolism of leukocytes and were readily killed by the phagocytes. The lack of killing of the other eight strains was shown to be due to absent or poor phagocytosis rather than to resistance to intracellular killing. Evidence was presented that the surface K antigen plays an important role in conferring antiphagocytic properties to some strains of E. coli. It was suggested that K antigen acts by interfering with the early step of the phagocytic process, that is, the attachment step.