IL-7 prevents apoptosis of T-ALL cells during in vitro culture.

T-ALL cells were cultured either in media alone or in the presence of IL-7. After 72 hours of culture, cells were harvested and stained with annexin V and propidium iodide as described in “Materials and methods,” and viability was determined by FACS analysis. Results obtained from one representative patient are shown and were similar to those observed in 10 of 12 patients studied.