Induction of HTLV receptor expression on IL-7–stimulated neonatal CD4⁺ lymphocytes.

(A) Adult and neonatal CD4⁺ T cells were isolated from adult peripheral blood (APB) and umbilical cord blood (UC), respectively, and cultured for 7 days in the presence of recombinant IL-7 (10 ng/mL). Expression of the HTLV and amphotropic MLV receptors as well as CD25 levels were monitored by FACS using H_RBD, A_RBD, and a PE-conjugated αCD25 mAb. Filled histograms depict control binding. (B) Cell cycle entry of IL-7–stimulated APB and UC CD4⁺ lymphocytes was monitored at day 7 by assessing the DNA content of PI-stained cells on FACS. Results are representative of data obtained in 3 independent experiments.