Inhibition of mitosis by chloramphenicol in phytohemagglutinin stimulated lymphocytes.

I TARIOUS CLINICAL AND EXPERIMENTAL STUDIES have shown V that chioramphenicol ( CAP) affects cell division. #{176} The characteristic aplastic marrow that is seen when toxicity is fully expressed suggests a toxic effect leading to depletion of dividing cells. The effect of CAP on incorporation of 32 into phytohemagglutinin ( PHA) stimulated lymphocytes was reported by McIntyre and Ebaugh,’ who found diminished specific activity of deoxyribonucleic acid ( DNA ), ribonucleic acid ( RNA), and acid soluble fractions after incubation with this drug. Similar inhibition of cell division was reported in other experimental models, such as poliovirus-infected Hela cells,2 human carcinoma cells in the logarithmic phase of growth,’ and cultures of chlamydomonas.4 On buccal smear preparations Barr bodies were found to have a smaller dimension after a week of clinical treatment with CAP.5 Mitotic activity of human bone marrow cells, especially of the basophilic normobbasts, was diminished to a slight degree after clinical treatment with CAP.6 When quiescent lymphocytes arc exposed to PHA, they transform to actively dividing cells, having all the characteristics of blast forms. By adding coichicine shortly before the culture is terminated, mitosis is arrested at metaphase and mitotic figures accumulate. The effect of drugs on blast transformation and mitosis has been reported, including chlorpromazine,7 chloroquine,5 prednisolone#{176} and others.’#{176} In this paper, our studies on the effect of chioramphenicol will be reported.