IL-7 promotes cell cycle progression in T-ALL cells.

(A) T-ALL cells were cultured for 72 hours in media alone or in the presence of IL-7, and proliferation was examined by thymidine incorporation. (B) At the same time interval IL-7–cultured cells were isolated, and the percentage of cells at each phase of the cell cycle was examined as described in “Materials and methods.” (C) Cells cycling in response to IL-7 are of malignant origin. After culture with IL-7, cells at the S+G2/M phases of the cell cycle were isolated by cell sorting and examined by RT-PCR by using patient-specific primers for the detection of a specific clonal TCR rearrangement identified at diagnosis. Results from one representative patient (P4) among 3 patients studied are shown. Primers used were specific for patient P4 and generated a PCR product from P4 (CS) but not from patient P2 (B1) or from normal T cells.