Cytokinetics and SCE baselines in rat and human lymphocytes during successive divisions in the presence of different culture media.

Peripheral blood cultures were set up from male rats and humans in TC199, RPMI 1640, and minimal essential medium in the presence of 5-bromo,2-deoxyuridine and harvested at 48, 72, and 96 h. Mitotic indices were compared in the different media at all three harvest times, but cytokinetic patterns and baseline sister chromatid exchange (SCE) frequencies were evaluated exclusively in the 72- and 96-h cultures. In general, lymphocyte division kinetics, as determined by average lymphocyte division (ALD) numbers, were comparable between rat and human lymphocytes cultured in any of the three media and harvested at either of the culture times. The numbers of SCEs were distributed between and within the two systems independent of ALD numbers or the harvest time. Overall, no influence of media was detected on the distribution of SCEs. Despite a number of similarities in growth characteristics between rat and human lymphocytes, the rat lymphocyte test system has distinct advantages over that of the human because of the easy access to rat blood samples and the absence of the many restrictions applicable to humans.