Mitotic cells in different lymphocyte subsets in unfractionated cultures stimulated by phytohaemagglutinin or pokeweed mitogen.

Unfractionated peripheral blood lymphocytes were cultured in the presence of either phytohaemagglutinin (PHA) or pokeweed mitogen (PWM) for 3 and 6 days. The subpopulations of mitotic lymphocytes were determined by an immunoperoxidase technique. Our results demonstrate that the proportion of mitotic B cells is approximately equal in PHA- and PWM-stimulated cultures. The frequency of mitotic CD22+ B cells varied from 3% to 5% and that of cells positive for the monoclonal antibodies anti-lambda and anti-kappa from 5% to 7%. We also showed that PHA stimulates mitoses in CD8-positive suppressor cells more effectively than does PWM. The mean proportion of CD8+ cells in mitosis was 29% when cultured with PHA for 3 days and 17%, in the presence of PWM. Culturing for 6 days with PHA increased the proportion of mitotic CD8+ cells, but PWM stimulation did not affect the frequency of mitoses in this lymphocyte subgroup.