RPMFs robustly take up OVA (a “weak” immunogen) but not FVIII. (A) Experimental timeline. S129/C57BL/6 HA mice were injected IV with FVIII-AF488 or OVA-AF488 (n = 3-5 per group). After 30 to 180 minutes, the spleens were collected for flow cytometry. (B) Quantification of FVIII-AF488⁺ or OVA-AF488⁺ cells in cDC1s (CD8α⁺CD11b^–CD11c⁺), cDC2s (CD8α^–CD11b⁺CD11c⁺), pDCs (PDCA-1⁺CD11c⁺), and RPMFs (F4/80⁺CD11b^–) 1 hour after administration of 5 μg FVIII-AF488 or OVA-AF488. (C) Quantification of FVIII-AF488⁺ or OVA-AF488⁺ cells in cDC1s (CD8α⁺CD11b^–CD11c⁺), cDC2s (CD8α^–CD11b⁺CD11c⁺), pDCs (PDCA-1⁺CD11c⁺), RPMFs (F4/80⁺CD11b^–), MZMs (F4/80^loCD11b⁺TIM-4^hi), MMMs (F4/80^loCD11b⁺TIM-4^lo), MZ B cells (B220⁺CD21^hiCD23^lo/–), transitional B cells (B220⁺CD21⁻CD23^lo/−), and follicular B cells (B220⁺CD21^medCD23^lo/–), 30 to 180 minutes after injection of 10 μg FVIII-AF488 or OVA-AF488. Shown are means ± SD, and P values from analysis of variance. MMMS, marginal metallophilic macrophages.