PMID: 6980934Oct 1, 1982Paper

Cell cycle regulation of cloned cytolytic T cells by T cell growth factor: analysis by flow microfluorometry

The Journal of Immunology : Official Journal of the American Association of Immunologists
R P SekalyM Nabholz

Abstract

In an attempt to better define the mode of action of TCGF we have investigated the effect of complete removal of TCGF on the cell cycle kinetics of a TCGF-dependent murine CTL cloned line (B6.1). Cells that had been cultured in the presence or absence of TCGF were stained with propidium iodide, a DNA binding dye, and the distribution of DNA content was analyzed by flow cytometry. Results indicated that the proportion of cells entering the S phase of the cell cycle started to decrease 6 hr after removal of TCGF from the culture medium. This fraction continued to decrease as a function of time, and after 30 hr without TCGF 93% of the cells were in the G1 phase of the cell cycle in comparison to 38% in control cultures containing TCGF. Direct evidence that B6.1 cells completed one cell cycle after removal of TCGF before they accumulated in the G1 phase was obtained with a technique combining the use of BUdR, a thymidine analog, and the DNA binding dye Hoechst 33342. When TCGF was added again to cultures of B6.1 cells that were arrested in the G1 phase, the majority of cells entered the S phase in a synchronous fashion after a lag phase of 10 to 12 hr. The duration of this lag phase was independent of the concentration of TCGF used...Continue Reading