How do you examine the reticuloendothelial system? You have certain procedures you perform for examining the other systems of the body. Most textbooks list the 10 major organ systems of the body that maintain homeostasis, but few mention specific examination procedures for the reticuloendothelial system.

That is because this very important system is not composed of visceral organs, but rather macrophages that are found in connective tissue. They carry on the process of phagocytosis or detoxification in critical areas of the body.

You will recall that 60% of body weight is water, and of that, two-thirds of this fluid is found inside the cells. The remaining one-third of total body water is found outside the cells and is referred to as the extracellular fluid (ECF).

It is only the ECF that is involved with maintenance of homeostasis, that critical process controlled by the autonomic nervous system and endocrine system through the direction of the hypothalamus. The ECF is composed of the fluid in the blood stream (20%) and the fluid outside the blood stream (80%) in the connective tissues. It is the macrophages in the fluid of connective tissues that comprises the reticuloendothelial system, or the macrophage system as it is sometimes called.

Obviously, since we are dealing with cells outside the blood stream, we cannot examine the blood to get definitive answers. Nor will urinalysis yield much useful information. X-rays, MRIs and cat scans are useless. Tissue biopsies are good, but outside the scope of practice for D.C.s. So, how do you examine this critical system, and why would you want to?

Macrophages are defined as mononuclear phagocytes found in the tissues. These cells arise from stem cells in the bone marrow. They develop into monocytes and circulate in the blood for about 40 hours.

Monocytes, as you know, are non-granular white blood cells that function as phagocytes in the blood. They are transformed into macrophages after leaving the blood stream and moving into the connective tissues. It is here that they undergo a magical metamorphosis increasing in size, phagocytic activity and lysosomal enzyme content.

The lysosomal sacs of these cells contain hydrolytic (digestive) enzymes that are active in an acid pH. This is an incredibly important point if you are using enzymes to enhance immune function. Pancreatic enzymes are not active in an acid pH environment, only in the alkaline environments found in the blood and small intestine.

Macrophages are most frequently concentrated in the following areas:

*** Loose connective tissues, which are especially numerous in mucous membranes of the digestive and respiratory tracts and in association with the lymphatics in the connective tissue of the pleura and peritoneum;

*** Lining the alveoli (terminal air sacs) of the lungs;

*** Lining the blood sinuses of the liver (Kupfer cells) and bone marrow;

*** Lining the sinuses of lymph nodes and the spleen, and

*** Microglia of the central nervous system. Microglia are small, non-neural, interstitial cells of mesodermal origin that form the supporting structure of the central nervous system.

Once in the connective tissues, the macrophages become powerful scavengers, even more powerful than neutrophils. They have the ability to engulf not only much larger particles but also larger quantities than the neutrophils.

Macrophages are capable of ingesting four times as much material as neutrophils before dying. They can even phagocytize whole red blood cells and malarial parasites, whereas -- neutrophils are not capable of phagocytizing particles much larger than bacteria. Also, macrophages have much greater ability to phagocytize necrotic tissue.

Phagocytosis

When these cells come in contact with extraneous particulate matter, either in the tissues or in the blood stream, the phenomenon of phagocytosis takes place extremely rapidly, the particle passing through the cell membrane to the inside of the phagocyte within a few hundredths of a second.

Obviously, the phagocytes must be selective, otherwise some of the structures of the body itself would be ingested.

Without going into great detail, it should be sufficient to say that phagocytosis is dependent upon certain selective procedures. For example, if the surface of a particle is rough, the likelihood of phagocytosis is increased, whereas a smooth particle is very resistant to phagocytosis.

Also, the body has a means of selectively combining foreign particles with globulin molecules called opsonins. Opsonins allow adhesion of the phagocyte to the surface of the particle, which promotes phagocytosis.

Once a foreign particle has been phagocytized, the cell immediately begins digesting the particle. Macrophages have proteolytic enzymes especially geared for digesting bacteria and other foreign protein matter, as well as large amounts of lipases which digest the thick lipid membranes possessed by certain bacteria.

In my upcoming columns, the focus will be on the individual organs that are supported by the reticuloendothelial system. I will discuss specific nutritional supplementation protocols for the spleen and lymphatic system, liver, and mucous membranes of the digestive and respiratory tracts.