IL-5–induced eosinophilopoiesis is diminished in Stat5a^−/− mice and Stat5b^−/− mice.

Stat5a^−/− mice, Stat5b^−/− mice, and wild-type mice were injected intraperitoneally daily for 4 days with 20 000 U of recombinant murine IL-5. Forty-eight hours after the last injection, mice were killed and the numbers of eosinophils in bone marrow (A), peripheral blood (B), and peritoneal cavity (C) were evaluated. Data are means ± SD for 5 mice in each group. *Significantly different from the mean value of wild-type mice, *P < .005.