Modulatory activity of chemotherapeutic agents on phagocytosis and intracellular bactericidal activity of human polymorphonuclear and mononuclear phagocytes.

Thirteen chemotherapeutic agents were tested for modulatory activity on phagocytosis by human granulocytes and monocytes. Phagocytosis, phagocytic index, and intracellular bactericidal activity were assessed using Staphylococcus aureus, smooth strain of Escherichia coli, and latex particles. Modulation of phagocytic activity depended on the type of particle used and the presence of serum in the medium. Testing granulocytes, only 1,3-bis(2-chloroethyl)-1-nitrosourea suppressed phagocytosis of all three types of particles used for ingestion. Other drugs suppressed either phagocytosis of E. coli and S. aureus or of one of the bacteria and latex particles. Three drugs enhanced ingestion of latex particles. The most pronounced modulation of phagocytosis was observed in conditions similar to those in vivo, namely, when serum was added to the medium and when the cells were exposed for longer time to the drugs. In the absence of serum, very little modulation of phagocytosis was observed, and only 1,3-bis(2-chloroethyl)-1-nitrosourea retained strong suppressive activity. Intracellular bactericidal activity was markedly suppressed by 7 of 13 drugs tested. Monocytes were less influenced by chemotherapeutic agents, their phagocytic activity being either suppressed or enhanced. The influence of chemotherapeutic agents on phagocytosis must be taken into consideration when assessing defense mechanisms and susceptibility to infection in patients with malignant diseases.