BISACK analysis of the phytohaemagglutinin-induced proliferation of human peripheral lymphocytes

The rate of stimulation as well as subsequent cell cycle duration was examined in phytohaemagglutinin-stimulated human peripheral lymphocytes grown in vitro in the presence of non-inhibotory concentrations of bromodeoxyuridine. After incorporation of this heavy atom analogue of thymidine into replicating cellular DNA, it was possible to identify unequivocally metaphase cells which had replicated for one, two and three or more cells cycles. Utlizing this technique, distribution curves were obtained for the appearance of metaphase cells in successive generations, were analysed by a computer simulation model, and the rate of stimulation (4.5% per hr of the reminaing unstimulated population) and cell cycle duration (12.3 hr) were determined. The results were compared with those obtained by autoradiography and the possible relationship to the 'transition probability' model for cellular proliferation is discussed.