Effect of antibiotics on CR1 receptor levels of human neutrophils and on the binding and phagocytosis of opsonized polystyrene microspheres by these leucocytes.

Fourteen antibiotics were studied for their effects on the following properties or functions of normal, human neutrophils: (1) the expression of CR1 receptors; (2) the total binding of C3b.IgG-coated polystyrene microspheres in the presence of cytochalasin D to inhibit phagocytosis; (3) the net phagocytosis of the opsonized microspheres; (4) the residual, external binding after phagocytosis. Fluorescence, flow cytometric methods were used to determine binding and phagocytosis of the model target particles. Only nafcillin, a penicillin, caused a decrease (33 per cent) in phagocytic capacity of the neutrophils at a physiologically significant dose (serum level); the antifungal antibiotic, amphotericin B, caused a 30 per cent increase in phagocytic capacity. These small changes in neutrophil phagocytic capacity may not be physiologically significant. There were no significant differences in the four measured parameters caused by other antibiotics tested at physiologically significant doses.