EFFECTS OF NEUTROPHIL, NATURAL-KILLER-CELL, AND MACROPHAGE DEPLETION ON MURINE CLOSTRIDIUM PILIFORME INFECTION

Clostridium piliforme infection (Tyzzer's disease) induces enterohepat ic disease in many domestic and laboratory animals. Murine susceptibil ity to Tyzzer's disease varies with host strain, age, and immune statu s. However, little is known about the role of the immune system in con trol of this disease. To investigate the role of host immunity in Tyzz er's disease, mice were depleted of either neutrophils, natural killer cells, or macrophages by antibody administration or chemotherapy. Aft er depletion, DBA/2 mice, which are naturally susceptible to C. pilifo rme, or naturally resistant C57BL/6 mice were inoculated intravenously with C. piliforme. Animals were euthanized 3 days postinoculation and evaluated for gross and histologic lesions and hepatic bacterial load . In juvenile DBA/2 or C57BL/6 mice, depletion of either neutrophils o r natural killer cells increased severity of disease. In adult mice, d epletion of natural killer cells significantly increased severity of T yzzer's disease in the resistant (C57BL/6) but not in the susceptible (DBA/2) strain. Macrophage depletion did not alter the course of infec tion in either mouse strain. These studies indicate an important role for neutrophils and natural killer cells in the pathogenesis of murine Tyzzer's disease. The role of macrophages in murine C. piliforme infe ction will require further evaluation.