Studies on the phagocytic activity of human and rat polymorphonuclear cells exposed to doxycycline in vivo.

Studies are presented on the in vitro phagocytic activity of rat and human polymorphonuclear leukocytes exposed in vivo to therapeutic concentrations of doxycycline. A 32P-labelled strain of Escherichia coli served as test microbe. No significant reduction of ingestion was observed although untreated AB leukocytes tested together with serum containing doxycycline showed a nonsignificant reduction in ingestive capability (p = 0.1). A similar pattern was observed when rat polymorphonuclear cells were tested omitting serum during the ingestion phase. In the presence of serum no effects were observed. During the elimination phase (3 h) both rat and human PMN eliminated breakdown products more extensively than controls, the effect observed on human PMN being most pronounced by the use of serum containing doxycycline.