Induction of ear swelling (A and B) and mast cell activation (C) by intradermal injection of rrSCF (30 μg/kg/site) or vehicle alone in the ear skin of WBB6F₁-Kit^W/Kit^W-v mice or Kit^W/Kit^W-v mice that had been selectively and locally reconstituted, in the left ear, with BMCMCs derived from the congenic normal +/+ mice (+/+ MC → Kit^W/Kit^W-v mice). (A) Ear swelling measured 2 hours after injection of rrSCF or vehicle. *P < .001 versus values for vehicle-injected +/+ mice or SCF-injected Kit^W/Kit^W-v mice. (B) Ear swelling determined 2 hours after injection of rrSCF into the left (mast cell-reconstituted) or right (mast cell-deficient) ears of +/+ MC → Kit^W/Kit^W-v mice. *P < .005 versus values for contralateral mast cell-deficient ears. (C) Extent of mast cell activation in the ear skin of +/+ mice after injection of SCF or vehicle or in the left (mast cell-reconstituted) SCF-injected ears of +/+ MC → Kit^W/Kit^W-v mice. *P < .0001 versus values for the SCF-injected +/+ mice or SCF-injected +/+ MC → Kit^W/Kit^W-v mice. The differences between values for SCF-injected +/+ or +/+ MC → Kit^W/Kit^W-v mice are not statistically significant (P < .1).