The effects of josamycin on the chemotactic response of blood polymorphonuclear leucocytes were studied. After oral administration of 2 g/day or 50 mg/kg/day for five days in man and rats respectively, polymorphonuclear chemotaxis was reduced by 20%. After in-vitro incubation with 10 mg/l josamycin chemotaxis was unaltered, whereas a 15% decrease was noted with 25 mg/l josamycin. These data suggest that josamycin is unlikely to severely impair chemotaxis in patients.
