PMCs dramatically change their phenotype on poly(I:C) stimulation. PMCs were characterized as c-Kit⁺, FcϵRI⁺, and S/T2⁺ cells (A). Expression levels of I-A/E (B), CD80 (C), CD28 (D), CD21/35 (E), and FcγRII/III (F), as analyzed on gated c-Kit⁺, S/T2⁺ double-positive cells, were analyzed before and 24 hours after injection of poly(I:C) by flow cytometry. Representative data from one mouse per group (n = 4-10) are shown. Horizontal bars in panels C-F indicate the percentage of MCs expressing the indicated molecules. Shaded and open curves show staining with specific antibodies and isotype-matched control antibodies, respectively.