Effect of chloramphenicol on the growth and viability of exponentially growing mouse leukemic cells (L5178Y)

Two effects of chloramphenicol on mouse leukemic cells (L5178Y) are described. The drug induces a prolongation of the cell cycle (reversible effect). The degree of prolongation is directly proportional to the concentration of the drug. The effect is observed only in the presence of chloramphenicol and cells return to normal cell-growth kinetics when the drug is removed from the culture medium. Chloramphenicol also kills a portion of the cell population immediately (irreversible effect). Data are presented which suggest that chloramphenicol is toxic to cells in the G2 phase of the cell cycle.