IL-7 up-regulates RANKL mRNA and RANKL secretion in T cells.

(A) Negatively isolated T cells from PBSCs were stimulated with IL-7 for 24 hours and RNA isolated. Semiquantitative RT-PCR was conducted as described in the “Materials and methods” section. IL-7–stimulated T cells showed up-regulation of RANKL expression. No RANK message was detectable in unstimulated T cells. (B) Secretion of RANKL into the culture supernatant was measured by metabolic labeling of purified T cells, followed by RANKL immunoprecipitation and SDS-PAGE (see “Materials and methods”). Soluble RANKL was detected in IL-7–stimulated cells but not in unstimulated cells. Data are representative of 2 independent experiments.