mSIGNR1 efficiently captures polysaccharide antigens in vivo.

(A) The MZM-specific antibody ER-TR9 stains 293T cells transfected with mSIGNR1 cDNA. 293T cells were transfected with mSIGNR1 cDNA and subsequently stained either with the mSIGNR1-specific antibodies 698 or ER-TR9 (filled histograms). Isotype controls are represented by open histograms. (B) Recombinant mSIGNR1 is specifically detected by ER-TR9 using a sandwich ELISA. ER-TR9–coated wells are incubated with recombinant mSIGNR1 and binding is detected by the mSIGNR1-specific antibody 698. SD is less than 0.05. (C,D) MZMs efficiently capture dextran-FITC in vivo. Naive mice were injected intravenously with FITC-dextran. Spleens were isolated and immunofluorescence analyses of murine spleen tissue sections were performed. Double stainings with FITC-dextran (green) and B220 (red, C) or mSIGNR1-specific antibody 698 (red, D) are shown. Original magnification × 200. (E,F) Dextran capture by MZMs in vivo is blocked by the mSIGNR1-specific antibody ER-TR9 and mannan. Naive mice were treated with either purified ER-TR9 (E) or the yeast-derived polysaccharide mannan (F) prior to intravenous injection with FITC-dextran. Double stainings were performed with FITC-dextran (green) and the mSIGNR1-specific antibody 698 (red). Original magnification × 200.