Cell cycle analysis of rat lymphocytes cultured with phytohemagglutinin in diffusion chambers

Abstract

Proliferation of rat leucocytes cultured with phytohemagglutinin in intraperitoneally implanted diffusion chambers was studied using 3HT autoradiography. Rats bearing fifty-hour old cultures were injected with 3HT and the cultures reaped serially. By 10–30 min after administration of 3HT, cells synthesizing DNA were labeled (over 50 per cent) and the labeling index did not change appreciably for 120 min thereafter, indicating a pulse label was achieved. Analysis of the labeled mitoses curve provided the following estimates: cell cycle time, about 12 hr; minimum post-synthetic rest period, less than 40 min; minimum DNA-synthesis time, about 6 hr; fastest mitotic time, approximately 30 min. The T s determined in the present study was shorter than values reported for mammalian lymphocytes stimulated with PHA in vitro. Ideal growth conditions in the in vivo cultures as judged by the excellent morphology of cells and the large numbers of blasts formed, may account for the short duration of T s and other subcycle times observed.