Restoration of C protein-induced myositis (CIM) in W/Wvmice engrafted with mast cells. (a) Cultured bone marrow-derived mast cells (BMMCs) of enhanced green fluorescent protein (eGFP) transgenic mice (1 × 107 cells) were injected intravenously into 6-week-old W/Wv mice (BMMC-engrafted W/Wv [W/Wv + BMMCs] mice). Four weeks after the transplantation, the presence of mast cells in skeletal muscle was evaluated. Representative photomicrographs of eGFP+ mast cells in skeletal muscle in W/Wv mice (as a control) and BMMC-engrafted W/Wv mice are shown. (b) Four weeks after the transplantation of BMMCs, CIM was induced in BMMC-engrafted W/Wv mice. CIM was induced in WT mice and W/Wv mice as controls. Twenty-one days after the induction, specimens of muscle from WT mice (n = 10), W/Wv mice (n = 11), and BMMC-engrafted W/Wv mice (n = 11) were stained with hematoxylin and eosin. Representative photomicrographs, histological scores (left panel), and necrotic muscle area (right panel) are shown. *P <0.01, **P <0.05.