Effects of tetracycline on human monocyte phagocytosis and lymphocyte proliferation

The phagocytosis and the spreading ability of cultured human monocytes were tested after administration of tetracycline (Tc) in vivo (14 days) and in vitro (24 h, 48 h, 72 h). As compared with untreated monocytes, in vivo medication had negligible effects on the cells' spreading ability and phagocytosis mediated via immune (Fc) and non-specific receptors. Addition of increasing concentrations of Tc in vitro (0-10 micrograms/ml), chosen to mimic in vivo therapeutic serum values, caused no statistically significant changes in the monocyte functions tested when all data were analyzed together. Regardless of Tc doses used, cultured monocytes showed maximum spreading and phagocytic activities after 48 h in vitro. Corresponding Tc exposure for 48 h in vitro had no effect on phytohemagglutinin-induced lymphocyte thymidine incorporation.