ABSTRACT
From around 1990, it has been suggested that our internal defense system is composed of two distinct elements ; local innate immunity principally arranged on surface areas to establish barriers against various pathogens, and systemic acquired immunity mainly seen in systemic compartments to survey and control internal damage and disorders. The former innate surface barrier is chiefly regulated via species-restricted CD 1 antigen-presenting molecules, through lipid/glycolipid antigens presented mainly by dendritic cells (DCs) and lacking antigen-specific memory through gene-rearrangements, while the latter acquired barrier is controlled by individually restricted MHC molecules and gains antigen-specific memory through gene-rearrangements. Surprisingly, it had been revealed more than 2,000 years before in the ancient Chinese medicine textbook, <i>Ko-tei-nai-kei</i>, that our defense system is also classified into two categories, named “defense-qi” and “nutritional-qi”, and shown that the former “defense-qi” is arranged at the surface of skin to control our sweat and interact with “muddy” substances, while the latter “nutritional-qi” is situated on and within blood vessels and produces purified nutrients from food, drink and other exogenous substances. In this review, based on our recent understanding of immunological progress and the modern concepts of immunity, the possible relationship between “defense-qi” and innate immunity as well as “nutritional-qi” and acquired immunity are discussed.