[Effects of local anesthetics on rat macrophage phagocytosis]

We examined whether phagocytosis by macrophages (M phi s) is affected by local anesthetics (lidocaine HCl, prilocaine HCl, mepivacaine HCl, tetracaine HCl and procaine HCl). Opsonized zymosan, fetal bovine serum and one local anesthetic were added to each M phi sample. After a 30-min incubation, M phi s were washed to make Giemsa stained slides for counting. The phagocytosis rate was calculated by counting the phagocytosizing M phi s per 200 cells with an optical microscope, and rates for the samples containing local anesthetics were compared with those for the non-treated samples. Inhibition of phagocytosis was reversible, dose-dependent and pH dependent for all local anesthetics. Tetracaine HCl inhibited phagocytosis most and procaine HCl, least. These results suggest that local anesthetics at the level of clinical use inhibit leukocyte phagocytosis and therefore may interfere with the normal function of cells fundamental to host defense.