Anti–c-kit treatment dramatically reduces the tissue MC infiltration and serum level of MMCP-1. After hematopoietic engraftment, on day +21 after transplantation, mice were treated with an anti–c-kit neutralizing antibody (ACK2) or an isotype-matched control antibody (J1.2). The effect of ACK2 treatment on the levels of intestinal (A) and skin (B) mast cells in F/P-positive CEL and mock vector–transduced recipient mice was assessed by morphometric analysis of chloroacetate esterase (CAE)–stained cells. Results are shown as means (± SEM) from 4 to 6 mice per group of 1 representative experiment of 2 independent experiments. *P < .05; #P < .001, compared with isotype control–treated mice. (C) The effect of ACK2 treatment on levels of MMCP-1 in the same groups of mice was assessed by ELISA. Each dot represents results from each individual mouse, and horizontal bars show mean values (n = 7-11 pooled from 2 independent experiments; **P < .001).