Generation of bone marrow chimera in mice.

For generation of bone marrow chimeric mice, the recipient WT and Axl^–/– mice or Gas6^–/– mice (5 weeks old) were lethally irradiated with 8.5 Gy of gamma ray before transplantation with bone marrow cells (5 × 10⁶) from 5-week-old donor male WT and Axl^–/– or Gas6^–/– mice via tail vein injection. After a 4-week recovery period, the mice were infected with RSV followed by S. pneumoniae infection.