THE IMMUNE SYSTEM OUR SECOND BRAIN

FRITJOF CAPRA

In this column, the author will explore theimplementations of the new understandingof life presented in his book, The Web of Life.
For an outline of this new conceptual framework,see Capra's 1995 lecture at Schumacher College,published in Resurgence 178.

ONE OF THE MOST revolutionary aspects of the emerging systems theory of life is the new conception of mind, or cognition, it implies. This new conception was proposed by Gregory Bateson and elaborated more extensively by Humberto Maturana and Francisco Varela in a theory known as the Santiago theory of cognition.'
The central insight of the Santiago theory is the identification of cognition, the process of knowing, with the process of life. Cognition, according to Maturana and Varela, is the activity involved in the self-generation and self-perpetuation of living systems. In other words, cognition is the very process of life.
It is obvious that we are dealing here with a radical expansion of the concept of cognition and, implicitly, the concept of mind. In this new view, cognition involves the entire process of life - including perception, emotion, and behaviour - and does not necessarily require a brain and a nervous system. At the human level, however, cognition includes language, conceptual thought, and all the other attributes of human consciousness.
The Santiago theory of cognition, in my view, is the first scientific theory that really overcomes the Cartesian division of mind and matter, and will thus have the most far-reaching implications. Mind and matter no longer appear to belong to two separate categories but are seen as representing two complementary aspects of the phenomenon of life - the process aspect and the structure aspect. At all levels of life, beginning with the simplest cell, mind and matter, process and structure are inseparably connected. Thus, for the first time, we have a scientific theory that unifies mind, matter and life.
Let me illustrate the conceptual advance represented by this unified view with a question that has confused scientists and philosophers for over a hundred years: What is the relationship between the mind and the brain? Neuroscientists have known since the nineteenth century that brain structures and mental functions are intimately connected, but the exact relationship between mind and brain always remained a mystery.
In the Santiago theory the relationship between mind and brain is simple and clear. Descartes' characterization of mind as the "thinking thing" (res cogitans) is finally abandoned. Mind is not a thing but a process - the process of cognition, which is identified with the process of life. The brain is a specific structure through which this process operates. The relationship between mind and brain, therefore, is one between process and structure.
The brain, moreover, is by no means the only structure involved in the process of cognition. In the human organism, as in the organisms of all vertebrates, the immune system is increasingly being recognized as a network that is as complex and interconnected as the nervous system and serves equally important co-ordinating functions.
Classical immunology sees the immune system as the body's defence system, outwardly directed and often described in terms of military metaphors - armies of white blood cells, generals, soldiers, etc. Recent discoveries by Francisco Varela and his colleagues at the University of Paris are seriously challenging this conception. In fact, some researchers now believe that the classical view with its military metaphors has been one of the main stumbling- blocks in our understanding of auto-immune diseases such as AIDS.
Instead of being concentrated and interconnected through anatomical structures like the nervous system, the immune system is dispersed in the lymph fluid, permeating every single tissue. Its components - a class of cells called lymphocytes, popularly known as white blood cells - move around very rapidly and bind chemically to each other. The lymphocytes are an extremely diverse group of cells. Each type is distinguished by specific molecular markers, called "antibodies", sticking out from their surfaces. The human body contains billions of different types of white blood cell, with an enormous ability to bind chemically to any molecular profile in their environment. According to traditional immunology, the lymphocytes identify an intruding agent, the antibodies attach themselves to it and, by doing so, neutralize it.
Recent research has shown that under normal conditions the antibodies circulating in the body bind to many (if not all) types of cell, including themselves. The entire system looks much more like a net- work, more like people talking to each other, than soldiers looking out for an enemy. Gradually, immunologists have been forced to shift their perception from an immune system to an immune network.
This shift in perception presents a big problem for the classical view. If the immune system is a network whose components bind to each other, and if antibodies are meant to eliminate whatever they bind to, we should all be destroying ourselves. Obviously, we are not.
The immune system seems to be able to distinguish between its own body's cells and foreign agents, between self and non-self. But since, in the classical view, for an antibody to recognize a foreign agent means binding to it chemically and thereby neutralizing it, it remains mysterious how the immune system can recognize its own cells.
Varela and his colleagues argue that the immune system needs to be understood as an autonomous, cognitive network which is responsible for the body's "molecular identity". By interacting with one another and with the other body cells, the lymphocytes continually regulate the number of cells and their molecular profiles. Rather than merely reacting against foreign agents, the immune system serves the important function of regulating the organism's cellular and molecular repertoire.
From the perspective of the Santiago theory, this regulatory function is part of the immune system s process of cognition. When foreign molecules enter the body, the resulting response is not their automatic destruction but regulation of their levels within the system's other cognitive activities. The response will vary and will depend upon the entire context of the network.
When immunologists inject large amounts of a foreign agent into the body, as they do in standard animal experiments, the immune system reacts with the massive defensive response described in the classical theory. However, this is a highly contrived laboratory situation. In its natural surroundings, an animal does not receive large amounts of harmful substances. The small amounts that do enter its body are incorporated naturally into the ongoing regulatory activities of its immune network.
With this understanding of the immune system as a cognitive, self-organizing and self-regulating network, the puzzle of the self/non-self distinction is easily resolved. The immune system simply does not and needs not distinguish between body cells and foreign agents, because both are subject to the same regulatory processes. However, when the invading foreign agents are so massive that they cannot be incorporated into the regulatory network, as for example in the case of infections, they will trigger specific mechanisms in the immune system that mount a defensive response.
The field of "cognitive immunology" is still in its infancy, and the self-organizing properties of immune networks are by no means well understood. However, some of the scientists active in this growing field of research have already begun to speculate about exciting clinical applications to the treatment of auto-immune diseases. Future therapeutic strategies are likely to be based on the understanding that auto- immune diseases reflect a failure in the cognitive operation of the immune network and may involve various novel techniques designed to reinforce the network by boosting its connectivity.
Such techniques, however will require a much deeper understanding of the rich dynamics of immune networks before they can be applied effectively. In the long run, the discoveries of cognitive immunology promise to be tremendously important for the whole field of health and healing. In Varela's opinion, a sophisticated psychosomatic ("mind-body") view of health will not develop until we understand the nervous system and the immune system as two interacting cognitive systems, two "brains" in continuous conversation.