Role of lymphocytes and the common γ chain for mast cells in Kit^W/Wv mice. Adoptive transfer of wild-type (R⁺γ⁺Kit^+/+) splenic lymphocytes into R⁻γ⁻Kit^W/Wv mice (D) lead to approximately 50% reconstitution of circulating T cells compared with Kit^+/+ (A) or Kit^W/Wv (B) mice. Nonreconstituted R⁻γ⁻Kit^W/Wv mice are shown as controls (C). Ears in these groups of mice were subjected to PMA treatment over a period of 6 weeks, and mast cell numbers in treated and untreated ears from all mice were determined by histology (E-H). The differences in mast cell counts comparing untreated (closed symbols) and PMA-treated (open symbols) skin samples had significant one-sided P values (P = .05, Mann-Whitney test) in panels E through H. The P value (.2) comparing the PMA-treated skins in panel G versus panel H was not significant (see text). Kit^+/+ were 13-week-old C57BL/6 mice (A,E). Kit^W/Wv (B,F), noninjected R⁻γ⁻Kit^W/Wv (C,G), and lymphocyte-recipient R⁻γ⁻Kit^W/Wv (D,H) mice were 17 to 20 weeks old. Donors (D,H) were 25-week-old C57BL/6 mice. To determine the possible role of γ_c for the defective mast cell reconstitution in R⁻γ⁻Kit^W/Wv mice, wild-type (R⁺γ⁺Kit^+/+) BMMCs were injected repeatedly (see “Material and methods” for cell numbers, frequency of injections, and duration of the experiment) into R⁻γ⁻Kit^W/Wv (J) and Kit^W/Wv (K) mice. Numbers of mast cells in the spleen, a site that is more effectively colonized than skin following intravenous transfer of BMMCs,³³  were determined by flow cytometry in noninjected controls (solid symbols in I-K) and in injected R⁻γ⁻Kit^W/Wv (J) and Kit^W/Wv (K). Age of the mice was 17 weeks (C57BL/6) (I), 9 to 11 weeks (noninjected R⁻γ⁻Kit^W/Wv) (J), 13 to 30 weeks (BMMC-injected R⁻γ⁻Kit^W/Wv) (J), 21 weeks (noninjected Kit^W/Wv) (K), and 39 weeks (BMMC-injected Kit^W/Wv) (K). Mast cells appeared in the spleens of both types of recipients, but their numbers were at least one order of magnitude higher in Kit^W/Wv compared with R⁻γ⁻Kit^W/Wv. The one-sided P value (.004) of the comparison of the BMMC-injected animals in panel J versus panel K by Mann-Whitney test was significant. Horizontal lines indicate the mean cell number for each group of mice (A-K). Hence, γ_c-competent mast cells did not rescue the defective mast cell reconstitution in R⁻γ⁻Kit^W/Wv mice.