A simple system for studying antibiotic binding to leukocytes.

Studies on the interaction between antibiotics and polymorphonuclear leukocytes (PMLs) usually require the availability of radiolabeled antibiotic, that the antibiotic kill intraleukocyte pathogens, or that the antibiotic affect some function of the leukocyte. The system described here does not have the requirements above but depends instead upon anti-staphylococci activity. The key features of the system are that, following incubation, extracellular antibiotic was removed from PMLs by centrifugation, contact between Staphylococcus aureus 502A and the phagocyte-antibiotic complex was assured by centrifugation at 4 degrees C in 96 well tissue culture dishes, phagocytosis was induced by incubation at 37 degrees C, and assessment of surviving bacteria was accomplished by collecting [3H]thymidine labeled bacteria using a cell harvester. Antibiotics that were active in this system included naphthalenic ansamycins (rifamycins and streptovaricins ), lincosaminides ( clindamycins and pirlimycins ), coumarins (novobiocin), erythromycin, tetracycline, tyrocidine and paulomycin .