Mast cells are critical for LN hypertrophy and immigration of LCs. (A) Imiquimod was applied daily to the ears of mice and total cell numbers in draining auricular LN were assessed on day 3. (B,C) LN cell suspensions from the experiments shown in panel A were stained for the expression of MHCII, Langerin, and PD-L1 using FACS analyses. Given are the percentages of Langerin-positive LCs out of MHCII-positive cells (B) and PD-L1–positive cells within the LC population (C). Shown are the means (± SD) from 6 to 8 mice per condition. *P < .05 versus Kit^W-sh/W-sh treated with imiquimod.