Reduction in mastocytosis using a suboptimal dose of ACK2 in vivo. Treatment with 125 μg ACK2 resulted in fewer c-kit⁺ cells in the bone marrow (A) and blood (B) day 5 after infection compared with the IgG-treated group (grayish bars). (C) Mast cells in the small intestine were also reduced (day 10 after infection), n = 4.