Inhibition of L5178Y Cells in Culture by Methotrexate and Antibiotics

Abstract
Methotrexate, tetracycline, gentamicin, streptomycin, and penicillin inhibited the growth of L5178Y murine leukemia cells in culture with I 50 (concentration of drug that caused a 50% inhibition of growth at 72 h) values of 0.0028 μg/ml (6.2 × 10 −9 M), 7.9 μg/ml, 200 μg/ml, 1,700 μg/ml, and 3,000 μg/ml (5,000 U/ml), respectively. At concentrations achieved clinically or utilized in the laboratory, the antibiotics did not alter the I 50 of methotrexate.