Migration of WASp-null LCs out of the epidermis is diminished. (A) Epidermal sheets were prepared following topical application of 0.1% oxazolone in AOO (acetone and olive oil) or AOO alone (vector). Staining with I-A^b+–FITC identified LCs and revealed fewer numbers of these cells in normal animals that had been sensitized compared with those treated with vector alone. In contrast, LC numbers in WASp-null sensitized animals were comparable in number to untreated animals. Top row, WT cells; bottom row, WASp-null. (B) Chart LC frequency in epidermal sheets prepared following topical application of 0.1% oxazolone in AOO (▪) or of AOO alone (vector, □). Oxazolone resulted in a marked fall in LC density compared with vector-treated WT mice (***P < .001; Student t test). This drop in LC density was also greater in normal compared with WASp-null sensitized animals (**P < .005). Additionally LC numbers from oxazolone-treated WASp-null mice did not vary significantly from vector-treated animals. The data shown are representative of 2 experiments in which n = 3 mice. Error bars indicate standard deviation.