Antibiotic accumulation in human polymorphonuclear leucocytes and lymphocytes.

Human polymorphonuclear leucocytes and lymphocytes were incubated with 10 different radiolabelled antibiotics (10 micrograms/ml) for 2 hours. The ratio of cellular concentration to extracellular concentration of the drugs was determined after centrifugation. For beta-lactam antibiotics and gentamicin the ratios were less than 1.0. The ratios for doxycycline, erythromycin, fusidic acid and rifampicin were 13, 4.3, 7-10 and 2.5 respectively indicating a cellular accumulation of these drugs. Erythromycin, fusidic acid and rifampicin were rapidly released from the cells in antibiotic free medium, while doxycycline was partly irreversibly bound.