Tetsunori Koizumi, Director

The idea that we humans are endowed with immune systems that protect us from external substances that threaten our health goes as far back as Huangdi, the legendary Yellow Emperor. Huangdi Neijing (The Inner Canon of the Yellow Emperor), which has been the canon for over 2,000 years for practitioners of Eastern medicine, explains how immunity works in terms of two types of qi-energy: wei qi (protective qi-energy) and ying qi (nutritional qi-energy).

The “protective qi-energy” and the “nutritional qi-energy” together protect us from the “evil qi-energy”, which refers to external substances in the environment that invade our body and cause illness. The “protective qi-energy” protects us from the “evil qi-energy” by establishing barriers on the skin surface by controlling perspiration and the body temperature. The “nutritional qi-energy”, on the other hand, protects us from external substances that have managed to enter the body through breathing, eating, and drinking by producing pure nutrients from the food and drink we consume. Transformed into blood, the pure nutrients are carried into various parts of the body. In contrast to the “protective qi-energy” that works on the skin surface, the “nutritional qi-energy” works within the body as the energy in the form of pure nutrients.

Modern Western medicine also explains how immunity works for us in terms of two types of the immune system, called the “innate immune system” and the “acquired immune system”. The “innate immune system” is the one that we have inherited from our parents, and is active from the moment we are born. The “innate immune system” goes into action immediately when it recognizes an invader. The invader is surrounded by the immune system cells, called phagocytes, and is killed inside these immune system cells.

The “acquired immune system”, on the other hand, produces cells called antibodies to protect us from an invader. Unlike the “innate immune system”, the “acquired immune system” does not go into action immediately because it needs to develop antibodies such as B-lymphocytes after the body has been exposed to the invader. Once these antibodies are developed, the immune system will protect us from the invader by recognizing and responding to it. Another important difference between these two immune systems is that, while immunity protection provided by the “innate immune system” is non-specific in that it works for all invading pathogens equally, immunity protection provided by the “acquired immune system” is specific in that it works only for specific types of invaders.

From the above descriptions of the “innate immune system” and the “acquired immune system” in modern Western medicine, it appears that the former corresponds to the “defensive qi-energy”, and the latter to the “nutritional qi-energy”, in traditional Eastern medicine. Huangdi Neijing (The Inner Canon of the Yellow Emperor) describes how the “defensive qi-energy” goes into action when the “evil qi-energy” from outside causes the blockage of qi-circulation in and around the body. The “defensive qi-energy” goes into action through changes in perspiration and the body temperature. Thus, the “defensive qi-energy” can be seen as playing the role of the first line of defense against disease-causing external substances, just as the “innate immune system” does.

The “nutritional qi-energy”, on the other hand, responds to the “evil qi-energy” from outside by transforming the nutrients from food and drink into blood, and thus circulates throughout the body, including the internal organs. It is not clear whether the “nutritional qi-energy” acquires a memory of the invader like the “acquired immune system” in Western medicine, but it provides us the internal protective power that we acquire in the form of nutrients circulating within the body.

While there are certain degrees of correspondence between the conception of the immune system in traditional Eastern medicine and that of the immune system in modern Western medicine, there is one important difference between the two, and that has to do with the ubiquitous nature of qi-energy. As the energy that pervades everything in the universe, qi-energy provides a vital link between the individual human being and the universe. In other words, the immune system serves as an interface, or a link, that connects us to all the living and non-living systems in the universe. This is indeed the reason why the question of health is not just a matter of how well our individual body is functioning, but is intimately tied up with the overall condition of the universe that provides us the air we breathe, the food we eat, and the climate for our living.

Immunology in Western medicine has undergone some important changes in recent decades to incorporate such a cosmic perspective as seen in traditional Eastern medicine. While classical immunology used to see the immune system as the body’s defense system, protecting us from external factors, new immunology sees it as an adaptive system that relates itself to these external factors and undergoes a process similar to biological evolution itself. To put it succinctly, the immune system is an adaptive system in the worldwide web of life and matter and keeps evolving along with all the other systems in the universe.

*An abridged version of the paper presented at the Science of Life Conference, May 8, 2021.