It is generally assumed that mast cells are the main source of histamine release in response to injury and wound healing.27, 28, 29, 30 However, using Hdc‐EGFP transgenic mice, previous studies revealed that CD11b+Gr‐1+ myeloid cells were the major HDC‐expressing cells in inflammation‐associated tumorigenesis19 and myocardial infarction.20, 31 This suggests that mast cells in tissues may play a role in the temporary storage of histamine derived from these HDC‐expressing cells, such as basophils and CD11b+Gr‐1+ myeloid cells. This evidence concerns the gene HDC and myocardial infarction.