Micronucleus formation in different lymphocyte subpopulations in peplomycin-treated and control cultures.

Spontaneous micronucleus formation and micronucleus induction by peplomycin in B and T lymphocytes was studied by a recently developed MAC (Morphology, Antibody, Chromosomes) method allowing the immunologic identification of different cell lineages. Blood samples from 3 healthy donors were cultured in the presence of phytohaemagglutinin and pokeweed mitogen. An increased frequency of micronuclei was observed in peplomycin cultures compared with controls. B cells were found to be more sensitive to peplomycin induction than were T lymphocytes. In control cultures, pokeweed mitogen yielded a higher frequency of micronuclei than did phytohaemagglutinin. In both pokeweed- and phytohaemagglutinin-stimulated cultures, B cells showed a higher frequency of micronuclei than did T cells. The relative proportion of mitotic B cells was equal in pokeweed and phytohaemagglutinin cultures. In peplomycin cultures, the proportion of B cells decreased as compared with control cultures.