IL-19 prevented chemotherapy- and irradiation-induced neutropenia. (A) Two-month-old C57BL/6 male mice were injected with cytarabine (100 mg/kg per day) followed by twice-daily injection of IL-19-1 (25 µg/kg), IL-19-2 (50 µg/kg), or G-CSF (100 µg/kg) from approximately 24 hours after cytarabine injection; mice were euthanized on day 9. The total number of neutrophils in PB was detected (mean ± SD; n = 10). (B) FACS analysis of BM and PB CD11b⁺Gr-1⁺ neutrophils in treated mice (mean ± SD; n = 10). (C) Level of G-CSF in serum of C57BL/6 mice (half male and half female) was detected by ELISA (mean ± SD; n = 10). (D) Two-month-old C57BL/6 male mice received 15 exposures of 0.3 Gy per day whole-body irradiation from day 1 to day 15 to induce neutropenia. Mice received injections of IL-19-1 (25 µg/kg), IL-19-2 (50 µg/kg), and G-CSF (100 µg/kg per day) from ∼24 hours after irradiation and were euthanized on day 16. The total number of neutrophils in the PB was detected (mean ± SD; n = 10). (E) FACS analysis of BM and PB CD11b⁺Gr-1⁺ neutrophils in treated mice (mean ± SD; n = 10). Data are mean ± SD of 3 independent experiments. **P < .01; ***P < .001.