Phagocytosis of enteric Campylobacter by human and murine granulocytes

The phagocytosis of enteric Campylobacter strains by murine and human granulocytes was studied in vitro. The number of fluorescein isothiocyanate-labelled bacteria per granulocyte was determined microscopically. The phagocytic index is strain-dependent, ranging from 0.05 to 0.4 bacteria per granulocyte. Human granulocytes phagocytose Campylobacter sp. with a twofold higher effectivity than murine cells. Opsonization with immune sera increased phagocytosis 11.6-fold; flagella-defective mutants were phagocytosed without opsonization with 3.3-fold higher effectivity than the isogenic mother strain. Stimulation and phagocytosis of granulocytes by 14 clinical isolates of Campylobacter sp. was monitored by measuring the oxidative burst and phagocytosis. Stimulation of granulocytes varied from 0.4 to 1.8 (relative units) and phagocytosis ranged from 0.03 to 0.68 bacteria per granulocyte. No statistically significant correlation among bio- or serovars and the degree of stimulation and phagocytosis was observed.