Heavy metal exposure and the human immune system

The role of interleukin-12 in the heavy metal-elicited immunomodulation: relevance of various evaluation methods
Original source: Journal of Occupational Medicine and Toxicology 2008, 3:25
Authors: Nasr YA Hemdan
Publication date: 6 November 2008
DOI (digital document ID): 10.1186/1745-6673-3-25
Requires subscription? No
Publicly-available abstract: Yes

Synopsis:
Heavy metals are known to affect the actions of T-helper (Th) cells and thereby affect the development of illnesses and disease. Interleukin (IL)-12, a crucial one of these cells, is one of the Th cells affected by outside agents. IL-12 promotes systemic inflammation and affects the body's response to disease. The author is testing to see if IL-12 levels are affected by heavy metal exposure.

Tests were run using both cultured human immune tissues and live mice. The human cells were cultured without exposure to either cadmium (Cd) or mercury (Hg). The mice were continuously exposed to sublethal doses of Cd or Hg salts for 3 or 5 weeks. Several different methods were used to evaluate the IL-12 levels.

IL-12 levels were dependent on levels of exposure to Cd or Hg, and on interferon-gamma (IFN-gamma) levels. The various measurement approaches were considered equally valid. In the absence of heavy metals, the interaction between IL-12 and IFN-gamma was shown to depend on the disease microorganism to which the cells were exposed.

Reliability:
The author is associated with several accredited institutions and appears to specialize in immunology. The tests were run redundantly using several different methods and came out the same each way, suggesting accuracy in the results received. The study was published in a peer-reviewed journal. The number of subjects (both human and rodents) was not explicitly stated, so it is difficult to tell if the results may be skewed by small sample size.

Practical Applications:
We are increasingly exposed to heavy metals and other environmental toxins; these are now shown to depress our immune systems. One of the difficulties in living long-term with diabetes is that the immune system is compromised. (Type 1 diabetes is an autoimmune disease.) This suggests that people with diabetes may need to be more careful than non-diabetics in minimizing our exposure to heavy-metal toxins. (Certain fish are known dietary sources of these toxins.)

I was curious to find out if the author had made any correlation between heavy-metal exposure and the development or progression of autoimmune disease. (He did not.)

This synopsis was based on the entire article.