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General interest items edited by Janice Flahiff

[Reblog] Your Immune System Is Made, Not Born

From the 29 January 2015 post at Scientific American

New research dispels the belief that the strength of the body’s defense system is genetically programmed
Cytomegalovirus

Cytomegalovirus infection.
Credit: Yale Rosen via Wikimedia Commons

Some people seem better than others at fighting the flu, and you might suspect they were born that way. A new study of twins, however, suggests otherwise.

In one of the most comprehensive analyses of immune function performed to date, researchers analyzed blood samples from 105 sets of healthy twins. They measured immune cell populations and their chemical messengers—204 parameters in all—before and after participants received a flu shot. Differences in three fourths of these parameters depended less on genetics than on environmental factors, such as diet and prior infections. Genetics had almost no effect on how well individuals responded to the flu vaccine, judged by antibodies produced against the injected material. And among identical twin siblings, who have the same genome, immune system features differed more strikingly within older twin pairs than in younger sets. The findings, published January 15 in Cell, argue that life habits and experiences shape our body’s defenses more than the DNA passed down from our parents.

Although prior twin studies had hinted that nonheritable factors contribute to some autoimmune disorders, such as multiple sclerosis, the recent analysis was one of the first to quantify genetic and environmental effects on the general immune system. “We were surprised by the degree of environmental influence on so many components,” says Mark Davis of Stanford University School of Medicine, senior author on the new study.

One finding was particularly striking. A single environmental factor—a past infection with common cytomegalovirus—affected 58 percent of the tested parameters. Whereas the results don’t show whether these changes produce an overall stronger or weaker immune response, they do indicate “cytomegalovirus has a really profound effect,” Davis says. The Epstein–Barr virus, another microbe that frequently infects people, had no such effect.

Read the entire article at http://www.scientificamerican.com/article/your-immune-system-is-made-not-born/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Science360NewsServiceComplete+%28Science360+News+Service%3A+Complete%29&utm_content=Netvibes

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January 30, 2015 - Posted by | Medical and Health Research News | , , , ,

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