Inhibition of Mitosis by Chloramphenicol in Phytohemagglutinin Stimulated Lymphocytes

1. When lymphocytes from human peripheral blood are treated with phytohemagglutinin, they undergo transformation to blast cells and then divide.

2. When chloramphenicol was added to the culture at the beginning of the experiment, mitosis was delayed but blast transformation was not affected.

3. CAP suppressed mitosis less markedly when added to the culture at 24 and 48 hours and more markedly when added daily.

4. Mitotic index was suppressed in two patients who had aplastic anemia due to CAP, in a manner similar to that observed in presumably normal people.

5. Possible reasons for this drug effect on cell division are discussed.