Effect of cyclophosphamide on in vitro phagocytosis of Staphylococcus aureus

An increase in susceptibility to infection in an untoward effect common to nearly all immunosuppressive agents. The present investigation was designed to examine potential causes of this decreased resistance to disease. Rats were treated with low dosages of cyclophosphamide, and the effect of such therapy on the in vitro phagocytic capabilities of polymorphonuclear leukocytes was examined. Intracellular destruction of phagocytized bacteria was not significantly altered as a result of treatment. However, the ingestion of Staphylococcus aureus was significantly impaired in the presence of serum from treated animals. Enzymatic analyses for various hydrolytic enzymes associated with reticuloendothelial tissue were also undertaken. Decreased levels of acid phosphatase within alveolar tissue was the only significant change noted as a result of treatment. The reduced phagocytic powers and enzyme levels observed in this investigation offer a partial explanation for the increased susceptibility to disease after treatment with cyclophosphamide.