Serum levels of IL-7 determined by ELISA.

Week 6 levels were determined immediately before starting IL-7 or placebo and week 10 levels approximately 12 hours after the last injection of IL-7 or placebo. Filled symbols indicate IL-7–treated animals; open symbols, placebo-treated animals. The black horizontal bar indicates the fact that treatment with IL-7 or placebo was given between 6 and 10 weeks after transplantation.