The internal damage caused by mercury exposure is not limited to the nervous system. The immune system can also suffer severe injury.64 Like the nervous system, the immune system is highly complex and involves many elements, including cellular components, cytokines, special hormones, and antibodies. It is also important to remember that the immune and nervous systems are intimately connected, both directly and indirectly, a connection that is especially important during development.
Low levels of mercury have several significant effects on the immune system. For example, one study involving eighty-one males occupationally exposed to mercury vapor, as compared to thirty-six controls, found that mercury stimulated T-lymphocytes including T-helper and T-suppressor cells in the exposed workers.65 In another study of forty-four workers exposed to mercury vapor, the majority with levels below the accepted toxicity limit of 50 ug/gram of creatinine, demonstrated increased levels of several humoral immune parameters, such as IgG, IgA, and IgM.66 This study found that mercury levels considered to be safe could stimulate humoral immunity, that is, antibodies.
So why is humoral immunity important? Because elevated humoral immunity coupled with T-cell malfunction leads to autoimmunity, a condition where the immune system inadvertently attacks various tissues in the body. There are numerous autoimmune disorders, including thyroiditis, rheumatoid arthritis, primary adrenal insufficiency, and lupus. In fact, we have good evidence that at least part of the damage caused by many neurodegenerative diseases is related to autoimmune reactions to cells in the nervous system.
In one study that used mice bred for autoimmunity, test animals were exposed to mercury vapor several hours a day for ten weeks. All mice receiving concentrations of mercury (480 ug/week/per kilogram body weight) developed auto-antibodies to their own DNA (antinu-clear antibodies).67 The lowest dose of mercury capable of producing antinuclear antibodies was 170 ug/week/per kilogram. Researchers found immune complexes within the kidneys, as well as deposited in the blood vessel walls. What this means is that anyone unlucky enough to have an increased genetic risk for any of the autoimmune diseases is at even greater risk of precipitating the disease after exposure to even low doses of mercury.
Further confirmation of the possible link between autoimmunity and mercury exposure comes from another experiment using autoimmunity-bred mice implanted with dental amalgam.68 The amalgam triggered an autoimmune reaction with elevations in IgG autoantibodies toward nuclear protein, and deposits of immune complexes, indicating a strong connection to the length of exposure and the dose of mercury used. This research confirms numerous other studies: exposure to mercury from amalgam fillings can chronically stimulate the immune system leading to autoimmunity.
There is growing evidence that many autoimmune diseases do not develop until some environmental trigger activates the process. In juvenile diabetes we know that cow's milk, certain viruses, and even MSG can trigger the onset of the disease. Mycoplasmal infections may trigger rheumatoid arthritis. Now we can add another trigger for several autoimmune disorders: exposure to low levels of mercury. The amount of mercury released as a vapor from dental amalgam fillings and dissolved into the saliva may be sufficient to trigger a disorder.
One recent observation may indicate a particularly dangerous complication associated with mercury exposure. In a Swedish study conducted on people before and after dental amalgam removal, researchers demonstrated that the number of resistant microorganisms found in the colon (but not in the mouth) increased significantly, by almost fivefold.69 The colon is a major site for microorganisms responsible for postoperative wound infections, and as we shall see later, may play a critical role in autism. Bacterial resistance has become a major public health problem, and has been recently blamed on the overuse of antibiotics. Now we have evidence that dental amalgams may be to blame, at least in part. Unfortunately, neither the Centers for Disease Control and Prevention (CDC) or the ADA are doing anything to correct this situation.
A particular type of white blood cell, the macrophage, plays a critical role in ridding the body of viruses, especially the herpes simplex type II virus. A recent study demonstrated that mice injected with low doses of mercury chloride before being infected with the virus had viral titers one hundred times higher than the control mercury-free mice.™ It appeared that the effect was caused by mercury inhibiting the release of important immune-related chemicals, called cytokines (interferon-alpha/beta and TNF-alpha), by the macrophage. These cytokines are essential for the macrophage's antiviral activity. In a human study, mercury was shown to inhibit the ability of neutrophils to kill the Candida albicans fungus, again an especially important factor in autism.71
The interaction between the immune system and the brain is especially significant during early development. For example, several special chemicals secreted by macrophages can adversely affect the brain, especially the immature brain. These powerful chemicals are released in rather high concentrations following prolonged immune stimulation (infections, vaccinations, or exposure to inflammatory chemicals). In a fairly recent study, researchers found that mice exposed to mercury responded by secreting large amounts of a special, very damaging, cytokine called interleukin-1 (IL-1).72 The increase in IL-1 production started six hours after the mercury dose was administered and reached a maximum concentration at forty-eight hours. The higher the dose of mercury, the greater the immune response.
This is important because IL-1 has been shown to inhibit a special carrier protein that clears dangerous levels of glutamate away from neurons. Excess glutamate, especially during brain formation, can cause variable disruptions of the brain's development. In the elderly, it can result in damage to special groups of neurons, a condition that may lead to neurodegenerative disease. We also have evidence that mercury can initiate an intense inflammatory response in tissues, followed by persistent inflammation.73 Again, this is critical to our understanding of the relationship to many brain disorders and mercury exposure.
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