Enhancement of human polymorphonuclear leucocyte motility by erythromycin in vitro and in vivo.

The effects of erythromycin on the migration, phagocytosis and antimicrobial activity of human polymorphonuclear leucocytes (PMNLs) were investigated in vitro. Therapeutic concentrations of erythromycin potentiated PMNL staphylocidal activity without affecting phagocytosis. PMNL random motility and migration to leuco-attractant endotoxin-activated serum (EAS) were significantly enhanced by erythromycin at concentrations of greater than 5 x 10(-5)M (16,5 micrograms/ml). To assess the possible in vivo significance of these findings the same PMNL functions were investigated in healthy adult volunteers before and 90 minutes and 1 week after the ingestion of a single 500 mg tablet of erythromycin stearate. PMNL migration to EAS and antimicrobial activity were significantly increased after ingestion of erythromycin and eventually returned to normal levels. A single intraperitoneal injection of 1,5 mg erythromycin lactobionate significantly increased the mean survival time of mice experimentally infected with Candida albicans. These micro-organisms are resistant to the antimicrobial effects of erythromycin. These findings show that erythromycin possesses nonspecific immunopotentiating properties which may contribute to the antimicrobial activity of this antibiotic.