IL-7 up-regulates both antigen-driven peripheral expansion and thymic-dependent T-cell regeneration.

The rhIL-7 was administered where indicated via continuous infusion subcutaneous pump at a dose of 5 μg/d from days 14 to 28 after BMT. Both panels show the number of splenic TCR Tg⁺CD8⁺ cells present on day 28 as determined using flow cytometry. MFI denotes mean fluorescence intensity of CD44 expression on the TCR Tg⁺ cells. (A) Thymectomized B6D2F1 hosts (L^d+) underwent syngeneic BMT as described in “Materials and methods.” LNs derived from the 2C Tg⁺/TCR mice were administered on day 0 at a dose of .03 × 10⁵ LN cells/mouse. (B) Thymus-bearing C57Bl/6 mice (L^d−) underwent BMT using T-cell–depleted BM from 2C Tg⁺/TCR mice as described in “Materials and methods.” No LN cells were administered. Mice treated with rhIL-7 show significant increases in the number of TCR Tg⁺ cells in both panels (P = .05, left panel, and P = .003, right panel). SEs of the mean are shown by error bars.