Immune System Diseases and PCBs
The elderly and very young people could be more susceptible to life-threatening sickness, as well as those who already suffer from weakened immune systems. Unfortunately, no one is studying this issue locally, so extra illnesses may simply blend in with the background of "normal" health problems in Northeast Wisconsin and Upper Michigan.
Infections and cancer aren’t the only concerns. PCBs may also increase the rate of autoimmune diseases, where a person’s immune system turns inward and attacks tissues in their own bodies. (see autoimmune section below) In addition, the immune system influences the development of many other systems. The human body is an interlocking network of interdependent systems.
The immune system includes: the bone marrow (in the hollow center of bones), the thymus gland (located behind the breastbone above the heart), adenoids, tonsils, spleen (located at the upper left of the abdomen), lymph nodes (along the lymphatic vessels with concentrations in the neck, armpits, abdomen, and groin), Peyer's patches (within the intestines), and the appendix.
All blood cells are manufactured by stem cells, which live mainly in the bone marrow, via a process called hematopoiesis. The stem cells produce hemocytoblasts that differentiate into the precursors for all the different types of blood cells --- erythrocytes (red blood cells), thrombocytes (platelets) and leukocytes (white blood cells) Leukocytes are the workhorses of the immune system. The leukocytes are further subdivided into granulocytes (containing large granules in the cytoplasm) and agranulocytes (without granules). The granulocytes consist of neutrophils (55–70%), eosinophils (1–3%), and basophils (0.5–1.0%). The agranulocytes are lymphocytes (consisting of B cells and T cells) and monocytes. Lymphocytes circulate in the blood and lymph systems, and make their home in the lymphoid organs.
During a baby’s development in the womb, the thymus gland processes many of the baby's lymphocytes, which migrate throughout the body via the bloodstream, seeding lymph nodes and other lymphatic tissue. The main cells to be processed are the T cells. T-lymphocytes govern cellular immunity which means they help cells recognize and destroy invading bacteria, viruses, abnormal cell growths such as cancer, and foreign tissue. If the thymus fails to develop or is removed early in fetal life, the immune system cannot develop completely. Normally, by the time the infant is a few months old, the immune system has sufficiently formed so as to function throughout life. However, further growth and development of lymphoid tissue still depends on intervention by the thymic cells. After the initial seeding process, the thymus releases a hormone that stimulates further growth of lymphoidal tissue.
(Please visit the Link webpages to learn more about the amazing complexity of the human immune system.)
PCBs have been shown to influence thymus function. A person with an underactive thymus gland will be prone to getting sick often. Infection will be more common and will often be chronic and prolonged. Allergies will also be more likely. Other symptoms include swollen glands, depression, extreme sweating, puffiness of the throat. Contributing factors to immune disorders which may also be influenced by PCBs:
The studies included here suggest that PCBs may be a factor in some autoimmune diseases in PCB exposed people, through sensitization or other negative immune enhancements.
Approximately 50 million Americans, 20 percent of the population or one in five people, suffer from autoimmune diseases. Women are more likely than men to be affected. Some estimates say that 75 percent of those affected -- some 37.5 million people -- are women. PCB exposures are widespread across the U.S. and even background levels of PCBs have been found to influence the immune system. Could PCBs be a significant contributor to this autoimmunity and widespread suffering?
In organ-specific disorders, the autoimmune process is directed mostly against one organ. Examples include asthma (respiratory system) Hashimoto's thyroiditis (thyroid gland), pernicious anemia (stomach), Addison's disease (adrenal glands), and diabetes (pancreas).
In non-organ-specific disorders, autoimmune activity is widely spread throughout the body. Examples include allergies, rheumatoid arthritis, systemic lupus erythematosus (SLE or lupus), dermatomyositis, fibromyalgia, and chronic fatigue syndrome.
The immune system normally can distinguish "self" from "non-self." Even so, some lymphocytes are capable of reacting against self, resulting in an autoimmune reaction. However, these lymphocytes are usually suppressed. Autoimmune diseases occur when there is some interruption of the usual control process, allowing lymphocytes to avoid suppression, or when there is an alteration in some body tissue so that it is no longer recognized as "self" and is thus attacked.
The exact mechanisms causing these changes are not completely understood; but bacteria, viruses, toxins (such as PCBs?) and some drugs may play a role in triggering an autoimmune process in someone who already has a genetic (inherited) predisposition to develop such a disorder. It is theorized that the inflammation initiated by these agents, toxic or infectious, somehow provokes in the body a "sensitization" (autoimmune reaction) in the involved tissues.
A relationship between hormones and autoimmunity has been inferred since the expression of many autoimmune diseases, and the severity of symptoms, seem to be related to changes in hormone levels. For example, estradiol (an estrogen) is produced by the ovaries and influences nerve cells, bone, muscle, and other endocrine glands, and metabolism in general. Hormones often provide communication between different systems. For example, estrogen can modify immune cell function, and influence the production of regulatory factors produced by immune cells and tissues. PCBs are hormone-mimics. Could PCBs be interfering in these processes?
Text References --- All information posted above (except the portion about PCBs) was gleaned from webpages listed in the Links section.