Human MoDCs express FcγRs that facilitate antigen cross-presentation. (A) FcγRI, II and III expression on human monocyte-derived DCs (MoDCs), cultured under serum-free conditions (n = 6). (B-C) Cross-presentation of pp65_495-503 to CD8⁺ T cells (n = 6). (B) Representative plots of CD8⁺ T-cell activation. MoDCs were loaded with HCMV derived pp65 and cocultured with A2/NLVPMVATV specific T cells. Freshly thawed T cells were gated based on CD3 en CD8 expression and analyzed for activation-induced production of IFN-γ (left), TNF (middle), and LAMP-1 surface expression (right). (C) Summary (mean + SEM) of HCMV pp65_495-503 cross-presentation. Bars represent production of IFN-γ (white), TNF (gray), and LAMP-1 (black) surface expression after coculture with MoDCs loaded with 0.3, 3, and 30 μg pp65 (n = 5-8). (D-G) Increased cross-presentation by FcγR targeting of pp65. (D) MoDCs were loaded with pp65 (top plots) or pp65-IC (bottom plots) and analyzed as in panel B. (E) HCMV pp65 was added across a range of Ab:Ag ratios and production of IFN-γ was analyzed (closed circles). Contribution of FcγR in IC-mediated cross-presentation by inclusion of FcγR-blocking reagents: purified IgG-Fc fragments (open squares) or recombinant S aureus–LIPr-like (open circles). (F) IFN-γ (closed circles), TNF (closed squares), and surface display of LAMP-1 (open diamonds) on CD8⁺ T cells. (G) Summary (mean + SEM) of IFN-γ production after IC-mediated cross-presentation in absence (black bar, n = 4) or presence of FcR blocking reagents (IgG-Fc-fragments, light gray; FLIPr-like, dark gray; n = 3).