IL-7–induced proliferation does not sensitize CD4⁺ lymphocytes to gp120-induced MAPK activation.

(A) CD4⁺ T cells were isolated from both UC blood and adult peripheral blood (APB) and cultured for 6 days in the presence of recombinant IL-7. Cell cycle entry was monitored at day 6 by assessing the DNA content of PI-stained cells on FACS. Cells in the S and G2/M phases of the cell cycle are indicated in each histogram. To directly assess cell division/proliferation, cells were labeled with CFSE and analyzed for CFSE intensity by FACS. The number shown above each peak indicates the number of cell divisions. (B) MAPK activation in proliferating IL-7–treated UC CD4⁺ lymphocytes was assessed following stimulation with gp120, SDF-1, or an αCD3 mAb, as indicated. Blots were reprobed with an αZAP-70 mAb to assure that expression of a T-cell–specific protein was equivalent in each lane. Data are representative of results obtained in 2 independent experiments.