Effect of cytokine administration on T-cell regeneration after BMT.

Animals underwent BMT as described in “Materials and methods” and received the cytokines as a continuous subcutaneous infusion at the doses and times noted for each panel. Open boxes represent BM-type cells (Thy 1.2) and hatched boxes represent LN-derived (Thy 1.1⁺) cells as quantitated by flow cytometry. Shaded bar represents approximate range Thy⁺ cells in normal, non-BMT hosts. Unpaired comparisons between groups were performed using the Mann-Whitney test. (A) rhIL-6 20 μg/d day −1 to day 27 following BMT, analysis on day 28. Thymus-bearing IL-6–treated mice showed marginally statistically significant increases in LN-derived cells (P = .05) but no significant change in Thy 1.2⁺ cells (P = .14). No significant differences were noted in thymectomized mice with or without rhIL-6. (B) rhIL-2 30 000 IU/d days 28 to 42 after BMT, analysis on day 42. Thymus-bearing IL-2–treated mice showed marginally statistically significant increases in BM-type Thy 1.2⁺cells (P = .05), and an increase in Thy 1.1⁺LN-derived cells (P = .02). No significant differences were noted in thymectomized mice. (C) rhIL-7 5 μg/d days 14 to 28 after BMT, analysis on day 28. Thymus-bearing rhIL-7–treated mice showed statistically significant increases in BM-type Thy 1.2⁺ cells (P = .01) and LN-derived cells (P = .009). Thymectomized IL-7 recipients also had significant increases in Thy 1.1 LN-derived cells (P = .001). SEs of the mean are shown by error bars.