In situ maturation of LCs induced by local injection of COL. (A) COL (1.2 μg per animal) or vehicle alone was subcutaneously injected into the right or left ears of BALB/c mice, respectively. Epidermal sheets prepared from the ear skin samples 48 hours after injection were stained for MHC II (green) and CD86 (red). Scale bar, 50 μm (original magnification 200×;20×/0.5 NA objective). (B) The same epidermal sheet preparations were examined for the number of MHC II–positive LCs, surface expression levels (MFI) of MHC II on LCs, and the frequency of CD86⁺ cells within MHC II⁺ LC populations using MetaMorph software. Data represent the mean ± SD (n = 3) measured by counting more than 10 independent fields in each specimen. (C) Cervical LNs were harvested 48 hours after subcutaneous injection of COL or vehicle alone to examine surface expression of MHC II and CD86 on CD11c⁺ DC populations by flow cytometry. Data represent the mean ± SD (n = 3) of MFI values. *P < .05, **P < .01 (compared with the controls treated with vehicle alone).