Fig. 6: Intravenously injected anti-FcγRIIIB-antigen conjugate in FcγR humanized mice generates nAPCs that accumulate in secondary lymphoid organs and promote T cell proliferation and target cell killing.

a Representative flow cytometry plots for blood 24 h after i.v. injection of indicated mice with 3G8-conjugate (3G8-fOva) (left panel). Percent of 3G8-fOva uptake (FITC⁺) (upper panel), acquisition of CD11c and MHCII on Ly6G⁺ cells (middle panel) and CD80 and CCR7 on the CD11c⁺MHCII⁺Ly6G⁺ population (lower panel) at indicated time points. b Percent CD11c⁺MHCII⁺ CD80⁺CD86⁺CCR7⁺ of Ly6G⁺cells in indicated organs 3 days after i.v. injection of 3G8-fOva or 3G8 without or with GMCSF. c Timeline of indicated treatments to assess CD4⁺ (OT-II) T cell proliferation in mice lacking MHCII; percent dividing Cell Trace Violet-labeled adoptively transferred CD4⁺ (OT-II) T cells, as assessed by CellTrace Violet dilution, in indicated organs. d Proliferation of adoptively transferred CellTrace Violet-labeled CD8⁺ (OT-I) T cells in spleen of indicated mice immunized 10 days prior with 3G8-fOva (left panel). Representative histograms of dividing (bar) and starting (Con, light gray) population of CD8⁺ T cells are shown. e Epitope-specific, target cell killing by endogenous CD8⁺ T cells following injection of Ova-peptide, SIINFEKL, pulsed or unpulsed target cells in indicated mice immunized 7 days prior with 3G8-fOva. FACS plots displaying CellTrace Violet-high (right peak) represent epitope-specific target cells, while low CellTrace Violet (left peak) represent unpulsed target cells. A relative reduction in the right versus the left peak indicates epitope-specific target cell killing. f Epitope-specific killing assay as in (e) in indicated mice treated with the neutrophil-immunodepleting antibody 1A8 or an isotype control. Data are mean ± s.e.m. One-way analysis of variance and Dunnett’s multiple comparison test was used for comparison of multiple groups. *p < 0.05, **p < 0.005.