April 16, 2004 | David F. Coppedge

Is It Possible to Be Too Clean?

Mr. Clean may have a bad immune system.  A story in EurekAlert says kids without enough exposure to infectious agents are at greater risk of autoimmune diseases.  “The cleaner everyone is, the less stimulation their immune system gets,” says [Nora] Sarvetnick [of Scripps Research Institute]. “Their immune system tends to be incomplete.”  Stimulation increases the number of T cells in the body, which “act as a buffer against the emergence of self-reactive T cells by shutting down homeostatic expansion,” a reaction to low T-cell count.  Sarvetnick’s hypothesis contrasts with prevailing opinion that views autoimmune diseases as functions of too much stimulation.  Apparently, segments of our immune systems, like soldiers, need things to practice on.  If there is no target, they practice on you.  “This hypothesis could explain a discrepancy in the number of cases of autoimmune disease in developed and developing countries,” the report says.  “Disease rates have been on the rise in developed countries in the last 50 years compared to their developing neighbors, presumably because people in less developed countries are exposed to more pathogens.”

This could lead to a new paradigm about infectious agents.  Since many are not pathogenic, maybe there are interactions between our cells and the environment that are not all bad.  Maybe instead of looking at every germ as an enemy, we should envision some of the microbes as engaging in “free trade” across our borders.  The problem then becomes regulating the commerce and preventing intrusion by terrorists.
    Microbes in the environment may be signalling our own bodies with information needed to adapt to changing conditions.  They might be providing a service, therefore, unless overwhelming us in swarms; the job of T-cells may be to regulate their numbers.  Pathogens may be formerly harmless agents gone bad or out of control.
    At this point, such thoughts are mostly hypothetical.  Certainly, harmful pathogens are to be avoided like the plague.  But we were created to be able to live outdoors in contact with our environment much of the time.  Cleanliness is still next to godliness, but disinfecting everything and using antibacterial soaps may be going too far.  Unless your kid has known allergies or genetic risk factors, let him or her enjoy pets and explore the wilderness – under your watchful eye.  Protect, but do not overprotect.

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Categories: Health, Human Body

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