EFFECT OF PENICILLIN-STREPTOMYCIN AND OTHER ANTIBIOTICS ON MELANOGENIC PARAMETERS IN CULTURED B16 F10 MELANOMA-CELLS/

Penicillin and streptomycin, the most widely used antibiotics in mamma lian cell cultures, caused a moderate stimulation in dopa oxidase and tyrosine hydroxylase activities, but a slight inactivation in the dopa chrome tautomerase activity of B16/F10 melanoma cells at the routine c oncentration (100 units/ml penicillin and 100 mu g/ml streptomycin) us ed for preventing bacterial growth in cultured animal cells. At these concentrations, tyrosinase activities and melanin content augmented wi th time during the first 24-48 hr. The opposite effect acted on cell v iability. After withdrawal of the antibiotics from the culture medium, the recovery of melanogenic parameters to normal values was fully rea ched after few hours (around 10), and it was already noticeable as soo n as 4 hr after removal. Other antibiotics used in cell culture, like kanamycin, gentamicin, and the antimicotic nystatin, exerted similar l ow effects at the recommended concentrations, always lower than two-fo ld and thus lower than those reported for amphotericin B. Taking into account these relatively low effects, and the high risk of contaminati on of mammalian cells culture without antibiotics, penicillin and stre ptomycin may still be routinely used in experiments leading to explore the melanogenic activity of malignant melanocytes in culture, unless very precise studies and strict conditions were needed.