SLC29A3 and Splenomegaly: Although human TLR8 expression under the control of its regulatory regions drives wasting diseases with leukocytopenia (Guiducci et al., 2013), Lyz2-dependent TLR8 expression, specifically in monocytes, caused neither leukocytopenia nor splenomegaly in WT mice (Fig. 6 E and Fig. S5 G) but drove monocytosis and splenomegaly in Slc29a3‒/‒Tlr7−/− mice (Fig. 6, E and F), suggesting that human TLR8 substituted for mouse TLR7 in Slc29a3−/− monocytes.