Transfused RBCs are consumed predominantly by macrophages and not DCs in the spleens of noninflamed mice. Syngeneic RBCs were labeled with DiO and transfused into recipient mice. Twenty-four hours later, splenocytes were harvested and either macrophages or DCs were visualized by staining with anti-F4/80 or anti-CD11c, respectively (A,B). Numbers represent percentage of cells in gate. Specificity was confirmed by staining with isotype matched controls (C,D). Numbers represent percentage of cells in gate. After gating on macrophages or DCs, DiO fluorescence was measured in each population (E,F) (–). Untransfused mice were used as a negative control to determine background fluorescence on the DiO channel (E,F) (------). Staining from representative mice is shown, and y-axes of histograms represent percentage of maximum peak value. This experiment was performed 3 times with similar results.