FcγRs on human BDCA-3⁺ contribute to antigen cross-presentation. FcγRI, II and III expression on BDCA-1⁺ and BDCA-3⁺ DCs extracted from human blood (A) and tonsils (B; BDCA-1⁺, dashed line) and (BDCA-3⁺, solid line; n = 3). (C) FcγRIIa (black bars) and FcγRIIb (white bars) mRNA expression in BDCA-1⁺ and BDCA-3⁺ DCs extracted from human blood (mean + SEM, n = 5). (D) relative FcγRIIa (black bars) and FcγRIIb (white bars) mRNA expression in BDCA-1⁺ and BDCA-3⁺ DCs (mean + SEM, n = 5). (E) BDCA-1⁺ (white bar) and BDCA-3⁺ (black bar) were FACS-sorted (at least 98% purity) and cultured in the presence of 3 μg pp65 (left bars) or pp65-IC (right bars; O/N, 37°C). Next, A2/NLVPMVATVCD8⁺ T cells were added to DC cultures and cross-presentation was analyzed as in Figures 1 and 2 (mean + SEM, n = 3). (F-G) Representative plots and summary of IFN-γ production (mean + SEM) after IC-mediated cross-presentation in the absence (black bar) or presence of FcR blocking reagents (IgG-Fc fragments (light gray), recombinant S aureus–FLIPr-like (dark gray; n = 3 in panel F; n = 2 in panel G).