Dendritic cell function in vitro : skin colonization, spontaneous emigration and antigen-stimulated migration. (A) Mouse ear epidermal sheets from wild-type animals (WT) and ADAP- deficient animals (ADAP) were stained with an anti-MHC class II antibody and the number of MHC-II-positive dendritic cells (DC) was counted microscopically (mean + SEM, n = 8 for WT, and n = 13 for ADAP). (B) Skin flaps prepared from the ears of mice were floated on tissue culture medium for 48 h. The numbers of CD11c-positive cells that spontaneously migrated into the culture medium were enumerated by FACS; (mean + SEM, n = 10). (C) Draining lymph nodes were collected 24 h after FITC painting. Cells were stained for CD11c, and the percentages of FITC-positive and CD11c-positive cells were analyzed by FACS (n = 10).