Fig. 1.
The IL-2 and IL-7 cytokines preferentially induce cell-cycle entry in recent thymic emigrants.
Naive (CD45RA+; TN) and memory (CD45RO+; TM) CD4+-resting T lymphocytes were isolated from umbilical cord blood (UCB) and adult peripheral blood (APB) by negative selection. Cells were cultured in vitro in the presence of IL-2 (100 U/mL) and/or IL-7 (10 ng/mL), and cell-cycle entry was monitored at day 4 by assessing DNA content of propidium iodide–stained cells on a FACScan cytometer (Becton Dickinson, San Jose, CA). The percentage of cells in the S and G2/M phases of the cell cycle are indicated, and results are representative of data obtained in 1 of 3 representative experiments.