Factors influencing the phagocytosis of Clostridium difficile by human polymorphonuclear leukocytes

Phagocytosis of Clostridium difficile by human polymorphonuclear leukocytes (PMNs) and the possible role of the clostridial toxins in this process were investigated. Phagocytosis of C. difficile was independent of aerobiosis and clearly depended on opsonization. Either complement or antibodies to C. difficile could serve as opsonins. Toxigenic strains of C. difficile were more resistant to phagocytosis than were nontoxigenic strains. Pretreatment of PMNs with as much as 10,000 units of toxins from culture filtrates of C. difficile for 2 h had no effect on either the phagocytic activity of PMNs or their viability as determined by trypan blue exclusion. In contrast, treatment of human embryonic intestinal cells with the same amount of toxin under identical conditions resulted in cell death.