Cell cycle analysis of human peripheral blood T lymphocytes in long-term culture.

We have studied the cell cycle of resting T lymphocytes from long-term (LT) cultures following stimulation with phytohemagglutinin (PHA) and recombinant Interleukin 2 (IL-2). We examined the kinetics of entry into S phase by autoradiography, the accumulation of cellular RNA by microfluorometric techniques, and ultrastructural morphology by electron microscopy. In addition, we examined the expression at the mRNA level of six cell cycle-dependent growth-regulated genes (c-fos, c-myc, KC-1, JE-3, vimentin, and histone H3). We show that T lymphocytes of LT cultures respond differently to mitogenic stimulation than the T lymphocytes of freshly isolated peripheral blood mononuclear cell cultures. At the ultrastructural, biochemical, and molecular levels, resting T lymphocytes of LT cultures can be distinguished from physiological (G0) lymphocytes of peripheral blood.