“The immune system cannot be considered in isolation. In fact, it can be thought of as part of a larger system which could be called the healing system. This larger system also includes the mind and attitudes, the brain, the nervous system, and the endocrine system.” – William Collinge

OVERVIEW OF THE IMMUNE SYSTEM

There are many ways to tell the story of immunity, and they all must grapple with its complexity. To attempt to describe the immune system requires us to artificially separate it from the rest of the body and the myriad other systems with which it relates. Of course, none of your body's systems exists in isolation. In fact, they literally flow into one another like a seamless garment, and you can not really find where one system ends and another begins.

Nonetheless, I will describe what are considered to be the main elements of the immune system.

The Sea of Microbes

Our environment is an ocean of life. This ocean is teaming with millions of viruses, bacteria, fungi, and other micro-organisms, and this abundance of living organisms does not stop at our skin. It is normal for us to have many different kinds of organisms living inside our bodies. Some are good for us, such as certain kinds of bacteria that live in our intestinal tract and help maintain healthy digestion. Others have the potential to cause symptoms of dis-ease or imbalance in how our bodies function. These latter organisms are called pathogens.

Usually we think of the surface of our skin as a boundary between us and our environment. In a sense, the skin serves as an interface between us and what is outside us - self and nonself. When we touch a tree, our skin is a boundary, the point where we, or the self, and the tree, or non-self, meet. But because our bodies are permeable, many microscopic organisms are able to penetrate our boundaries.

Hence we need another level of protection inside the body to distinguish self from non-self. This is the function of the immune system - to provide internal protection from non-self organisms or materials that penetrate our boundaries. The immune system is our internal interface between self and non-self. As we shall see, the immune system is able to distinguish between friend and foe, and to protect us from materials which do not belong.

The Balance of Nature

The notion of the balance of nature means that we are living in balance or harmony with life around us. However, it does not apply only to the grand scale of ecological crises and endangered species in the outer world. It also applies to the environment inside our bodies. In fact, many definitions of health often refer to living in balance. This implies that all of our internal life processes are somehow in harmony or rhythm with each other.

Within our bodies, as in outer nature, one of the principles for maintaining balance is that of predators and prey. Certain organisms perform the function of limiting the growth of other organisms which could upset the balance, and could ultimately lead to the demise of the entire system. In the human body this principle takes the form of the immune system hunting down and destroying pathogens. The immune system is predatory, with its white cells literally hunting down and preying upon pathogens such as viruses, bacteria, and fungi.

Because we are constantly immersed in this sea of life, it is normal for us to have these organisms within us, and it is normal for the immune system to routinely detect and destroy them, usually without our ever being even aware of it. It is normal for us to have cancer cells arise, and again, for our immune system to quietly destroy them before any noticeable pathology could ever develop. We are in a state of dis-ease when the balancing principle has somehow been interfered with or the immune system has been unable to respond as needed to maintain the balance.

With these principles in mind, let us now consider the major parts of the immune system.

The Bone Marrow [birthplace of white (immune) blood cells]

The marrow has been often used as a powerful symbol in poetry and literature, referring to the deepest recesses of one's being. There is perhaps a universal understanding that to penetrate to the marrow is to penetrate to the core. This symbolism is certainly an accurate one when considering the human body, for without the marrow we could not live.

The marrow is a spongy tissue that fills the hollow spaces in our bones. You can think of the marrow as a vast vineyard, with billions upon billions of vines bearing fruit. The vines represent what are called stem cells. These are the cells which continuously bear fruit in the form of red cells and white cells. They give birth to the red cells and platelets of your blood. They also give birth to all your white cells, which do the work of your immune system. As these offspring of your stem cells mature and ripen, they detach and are carried out into the body by your circulatory system.

The Thymus Gland [where some white cells become “T” cells]

After your white cells leave the bone marrow, about half of them migrate directly to the thymus gland. The thymus is a small, walnut-sized gland located behind the breast bone. Only in recent years has it been understood as an integral part of the immune system. It serves as an incubator for certain white cells. Those cells which migrate to the thymus become "T" cells - "T" for "thymus-derived."

There are basically four types of T-cells (discussed below). These include T-helper cells, T-suppressor cells, T-killer cells, and T-memory cells. Each of these performs a vital function in your immune system.

The Spleen [reservoir for white cells]

The spleen is another region of spongy tissue, located deep in the abdomen between your stomach and left kidney. It too is not completely understood, but it serves as a reservoir for immune cells to be stored and to interact with each other. As we shall see later, communication among white cells is an important function of the immune system, and the spleen assists with this. Damage to the spleen can result in increased vulnerability to infection.

The Immune Cells [white cells]

Finally we have the immune cells themselves, also called white cells. There are many different types of white cells, which can be lumped into a few broad categories. If you can bear with this explanation, you will see that the immune system is an incredibly intelligent, well-organized system.

T-Helper Cells [trigger the immune response]
One of the most important functions of the immune system is performed by the T-helper cell. That function is to turn on or arouse the immune response. The T-helpers receive information from other white cells that tells them of the presence of a threat.

The T-helpers then release messenger molecules, called cytokines, into the bloodstream. These messages are received by the other white cells, which in turn respond with heightened activity, mounting a response to the offending material, whether it is a virus, bacteria, cancer cell, toxic substance, or other threat.

The T-helper cell is considered the trigger of the immune response. Unfortunately, it is one of the primary targets of the human immunodeficiency virus in AIDS. If the T-helper cell is injured or killed, then the person's immune response will be compromised, and they will be more vulnerable to infections. This of course is how AIDS becomes a life threatening illness. People who suffer from AIDS do so as a result of infections that would not be such a threat in a normally aroused immune system.

T-Suppressor Cells [turn off the immune response]
These are the cells which turn off the immune response after a threat has passed. The T-suppressors also release chemical messengers into the bloodstream to the other white cells. These chemicals have the effect of announcing that the battle is over and it is safe now to relax the defense forces and move back into a state of routine surveillance.

Immunologists have found that the ratio of T-helper cells to T-suppressor cells is an indication of the health of the immune system. The normal T-cell ratio is approximately 1.8 T-helper cells for each T-suppressor cell. This is the ratio in which the immune system is in balance and runs most harmoniously.

There are many diseases in which the ratio is out of balance, one way or the other. For instance, some lymphomas may have a ratio of 4:1 or higher, and multiple sclerosis may range from 2.5:1 to 2.8:1. AIDS, on the other hand, may be 1:1 or less, because of the toll the AIDS virus takes on T-helper cells. In the Tahoe study [involving a still-evolving self-help program for ME/CFS patients that Dr. Collinge developed in collaboration with Dr. Daniel Peterson, MD, in Incline Village, Nevada]. CFS patients were found to have a ratio of 3.16:1, a clearly abnormal ratio.

T-Killer Cells [search and destroy]
There are several types of white cells which do the work of actually killing or removing unwanted material. The T-killer cell is one of these. It has receptors on its surface which receive the chemical message from the T-helper cell. The receptor is like a satellite dish, which accepts the message and processes it. After this communication has taken place, the T-killer knows what kind of target to look for and springs into action.

It is not entirely clear how T-killer cells find their targets, but it is probably through some kind of electrochemical attraction. Once they encounter the unwanted tissue, they use chemical warfare to destroy it. This means they literally come up against the surface of the offending organism and inject poison into it. The poison dissolves a hole in the wall of the offending cell, its insides spill out, and it dies. Once the battle is over, the T-killer cell receives the message from the T-suppressor to retreat, and it returns to a mode of surveillance.

T-Memory Cells [store info about past encounters]
As I stated earlier, the immune system is intelligent. This means it communicates, has senses, and also has memory. The T-memory cells perform the function of storing information about past encounters with disease-causing agents. This enables the immune system to respond to an invader more quickly, because it does not have to go through the work of drawing up a profile and identification of the offender.

In a sense, the information is already filed in the memory bank, enabling more rapid recognition and analysis of the offender to take place, and an overwhelming immune response may be mounted more quickly. This is the principle on which immunizations and inoculations are based.

Macrophages [cleanup & surveillance]
As stated earlier, only about half the white cells leaving the marrow become T-cells. The other half become macrophages, natural killer cells, and B-cells.

Macrophages are the largest cells of the immune system. Their name literally means "the great eaters." Their function is to roam throughout the body picking up debris, digesting it, and removing it. They keep the body clean, in a sense, constantly on the look out for diseased, dying, or dead tissue.

Occasionally a macrophage will encounter a pathogen such as a virus, bacterium, or other invader. When this happens, the macrophage will take a piece of material from this invader and bring this evidence to the attention of the T-memory cell for identification. In this way, macrophages play an essential role in surveillance of the body. They are also involved in eating and removing diseased or dead tissue, including the remains left by the work of killer cells.

As do all the other white cells, macrophages do have certain vulnerabilities. One is that sometimes they can be penetrated by a dangerous virus, such as HIV. In this instance, rather than killing its host cell, HIV may simply live within the macrophage and go along for the ride. Unfortunately this is one of the routes by which viruses may penetrate through the blood-brain barrier and gain entry into brain tissue. Once in the brain, they can cause symptoms. Many of the symptoms of CFS are thought to be caused by the effects of viral activity on brain tissue.

Natural Killer Cells [T-killer cell backup]
If there is to be a hero in the immune system, the Natural Killer (NK) cell is a good candidate. This is because NK cells are extremely powerful and important. They are thought to play a major role in the destruction of both cancer cells and cells which are infected by viruses.

The NK cell functions like a free spirit. Since it is not part of the T-cell network, it is not dependent on messages from the T-helpers or T-suppressors to regulate its activity. On their own, NK cells are able detect the presence of a cancerous or virus-infected cell, and destroy it. The killing process is the same as that described earlier for the NK's close cousins, the T-killer cells.

Because they are free spirits, NK cells play an important role in diseases where T-helper function is deficient. It is believed that long-term AIDS survivors do well because their NK cells are compensating for a deficient number of T-helper cells. This demonstrates one of the important features of the immune system, called redundancy - the ability of other parts of the system to pick up the slack and compensate when one part is having difficulty. Overall, the NK cell is considered a symbol of the fighting spirit of the immune system.

B-Cells [design and memory of virus-neutralizing antibodies]
So far we have been discussing the activity of white cells which directly encounter and confront unwanted organisms - in a sense, cell-to-cell combat. Those activities described comprise what is called "cellular immunity." This refers to the activity of individual cells in defending the body directly.

There is another kind of immune activity, however, which is called "humoral immunity." Humor refers to blood, and humoral immunity involves the circulation throughout your body of substances which are produced by your white cells.

This type of immune response is directed by B-cells. These cells tend to cluster around your lymph nodes, where they can easily monitor foreign materials, for example viruses, which may be circulating through the body. The B-cell is alerted to the presence of a virus, either by a macrophage or by T-helper cells, and rather than attacking the virus directly it begins producing antibodies for that virus.

Another name for antibody is immunoglobulin (Ig). The antibodies are released into the blood stream where they attach themselves to viruses, neutralizing them until a macrophage comes along and devours the antibody and virus together. In a sense the antibody acts like a ball and chain to the virus, rendering it unable to penetrate a cell and cause disease.

The B-cells manufacture millions of antibodies for viruses which have been detected in the body, and each type of antibody is tailor-made for a specific type of virus. Each type of virus you have been exposed to in your life is remembered by your immune system, and each has a corresponding template stored in the memory of your B-cells.

Should a given virus from your past be detected again, the response of your B-cells will be swift in mounting the antibody response. Should it be an encounter with a new virus, the response will be slower because of the time needed to design the new antibodies.

Finally, the B-cells respond to the level of viruses in the body, and adjust their output accordingly.

In Summary
There are several qualities your immune system has which give reason for hope. These include the fact that it is intelligent, it communicates, it has memory, it has senses, and it is creative. In addition, it has certain qualities of redundancy and compensatory mechanisms - that is, it has several alternative ways of responding to a problem, and if one part of the system is having difficulty, other parts can pick up the slack.

AN OPEN SYSTEM

The immune system cannot be considered in isolation. In fact, it can be thought of as part of a larger system which could be called the healing system. This larger system also includes the mind and attitudes, the brain, the nervous system, and the endocrine system.

The interaction among all these systems is the subject of the science of psychoneuroimmunology (PNI). One of the most important messages of this new field is that the immune system is an open system - that is, it does not act alone, but is very much influenced by communication with these other systems.

The Neuroimmune Network

How does this communication take place? One the most important insights of PNI is that the brain is a gland. As such, it releases chemicals into the bloodstream which communicate with the white cells. As mentioned earlier, white cells have receptors - like satellite dishes - on their surfaces which receive these chemical messages, decode them, and use the instructions to influence the behavior of the cell.

Another means of communication between the brain and white cells is the nerve endings reaching from the brain all the way into the bone marrow, thymus, and the other organs of the immune system. These nerve endings can stimulate the production of white cells in the marrow. They are also able to stimulate the activity of the thymus gland and other organs.

The nervous system also has receptors embedded in the organs of the immune system, along the walls of the blood vessels, and in the brain. These receptors are able to receive chemical messages released by the white cells, and send this information back to the brain. These signals can tell the brain about the status of the immune system and its activity. The brain can in turn respond with further release of chemicals or nerve impulses to stimulate the immune responses in the desired way. Hence there is constantly two-way communication between the immune and nervous systems.

These two modes of communication - chemical messages and nerve impulses - are the means the brain uses for mind/body communication.

Dr. William Collinge is an international leader in the development and use of complementary therapies to address the psychological, physical and spiritual aspects of illness and healing in ME/CFS and FM. This information is excerpted with permission from Chapter 4 of Dr. Collinge's book Recovering from Chronic Fatigue Syndrome: A Guide to Self-Empowerment, which is offered free in its entirety on his website (http://www.collinge.org).