In the biological defense mechanisms against infectious diseases, cell surface molecules derived from microbes, particularly glycans and complex carbohydrates, play an important role in activating the host’s immune system. That is, various complex carbohydrate structures derived from microbes are recognized by innate immune receptor families such as TLR [1], CLR [2], NLR [3], RLR and recently identified ALPK1 [4, 5]. This recognition leads to activation of immune mechanisms for microbial elimination and defense against infection, as well as modulation of the balance between cellular and humoral immunity via CD1-dependent activation of acquired immune responses (Fig. 72.1). These processes include enhancement of antibody production and induction of cytotoxic effector cells, which collectively modulate immune responses. Research in Japan in this field has been at the forefront worldwide, including in the discovery and functional characterization of the afore mentioned innate immune receptors and their ligands.