[Basic background for adjuvant immunotherapy]

Pattern recognition receptors (PRRs) are evolved for sensing microbial infections by recognizing microbe--specific patterns to activate the innate immune system. In PRRs, Toll-like receptors(TLRs) are best characterized as a maturation inducer for dendritic cells and shown to participate in host defense and cellular immune responses against infection and cancer. Cancers usually harbor antigens but lack PRR agonists, namely adjuvant, that essentially differs from infections provided with antigen and adjuvant. Here we briefly review the role of TLRs in the aspect of adjuvant receptors which evoke innate and cognate immunity, and discuss the progress of clinical studies in the context of antitumor immunotherapy.