ALPK1 and infection: In epithelial cells, others showed that ADP-heptose can effectively enter a host cell to trigger inflammation via its cognate receptor ALPK1, activating the classical or alternative NF-κB signaling pathway.15,17,19,20 Since we observed increased DC activation upon infection with ADP-heptose-deficient bacteria, we next asked whether ADP-heptose alone has any effect on human primary DCs.