AUBREY/ANYONE PLEASE.

[Guest guest]

Aubrey,

This article was in the U.S. News and World report.

It sounds like this new “theory” could be very important.

Pease

read and tell me what you think. Barb in Texas

Myths, mothers, and

modern medicine

Do 'chimeras'

trigger some women's illnesses?

By K. Sobel

With fiery breath and woolly torso, the beastly Chimera

of ancient Greek mythology bears little resemblance to modern-day woman.

Yet scientists are drawing a striking connection between the two. The

legendary creature, with a lion's head, goat's body, and serpent's tail, is

an amalgamation of beings. And so, too–and this is not myth–is woman.

Circulating within a woman's body are not only her own

cells but also those of her children. These cells, normally numbering less

than one in a million, linger in a mother's bloodstream for years or even

decades after she gives birth. Such a biological melding of individuals,

called " fetal cell microchimerism, " has garnered attention

recently in scientific circles. Indeed, it may help solve a longtime

mystery: Why do autoimmune diseases, in which a body's cells inexplicably

attack its own tissues, strike women roughly three times as often as men?

A new theory, proposed by rheumatologist J. Lee

of the Fred Hutchinson Cancer Research Center, suggests that the

" chimeric " cells initially left behind by a fetus during

pregnancy may actually be the agent that turns a woman's body against her

own tissues years later. In multiple sclerosis, for example, these

" foreign " cells might prompt a woman's own defenses to

misperceive the insulation surrounding her nerve fibers as " nonself " –and

thus attack.

This radical rethinking of autoimmunity is gaining

support at a propitious moment. Last week, the Institute of Medicine issued

a report– " Exploring the Biological Contributions to Human Health: Does

Sex Matter? " –urging scientists to evaluate sex differences at the

cellular and molecular level to understand their impact on human disease.

And has begun a crusade to do just that. " Her work with

autoimmunity is a great example, " says Harvard Medical School's

Faustman, who is familiar with the report.

So far, 's initial findings have captivated peers.

" She came up with an original and rather unlikely idea but had the

courage to stick with it, and now others are paying attention, " says

Noel Rose, professor of pathology and immunology at s Hopkins. 's

team recently examined women with scleroderma, an autoimmune disease that

causes hardening of the skin and internal organs. These women, it turns

out, harbor on average more than 25 times as many fetal cells in their

blood as women without the disabling ailment.

Other scientists have begun to sleuth around, too.

" It looks like a real phenomenon, " says endocrinologist Terry

Davies of Mount Sinai School of Medicine, who recently began studying the

connection between fetal cells and autoimmune thyroiditis. Not only did his

team find that fetal cells turned up in women with the disorder more often

than in women without it, but they also found that the fetal cells for some

reason accumulated at the site of disease, the thyroid gland.

Mothers' cells.

Questions remain. What about men who get autoimmune diseases? Or women who

have never been pregnant? Or children? argues that her theory can

accommodate these less common occurrences. During pregnancy, while a mother

inherits fetal cells through the placenta, a fetus also acquires maternal

cells. It's these foreign cells circulating in grown men, women, and

children that could later activate autoimmunity.

The presence of such foreign cells is clearly not

synonymous with disease, since everyone can harbor at least some. But

has an idea about why certain people get sick and others don't. If

fetal cells are especially similar to maternal cells (or vice versa), they

can more easily sneak past initial defenses and then creep into the intricate

network of the immune system to disrupt it. " We don't think they are

mounting an all-out attack, " says . " The key is

trickery. " has already found some support for this idea: The

risk of scleroderma increases when HLA proteins–markers that the immune

system uses to distinguish its own cells from others–match up between fetus

and mother.

Still, some scientists have reservations. " The

concept of microchimerism is not going to be a generic answer to

autoimmunity, " says the University of California- 's M.

Gershwin, noting that genetics and infections probably play some role, too.

His team investigated primary biliary cirrhosis, an ailment where cells

attack one's own bile duct. Diseased and healthy women had similar levels

of fetal cells in their livers.

The next step is to actually demonstrate that excessive

nonself cells actually cause autoimmunity. If that can be shown, scientists

foresee using targeted therapies, such as monoclonal antibodies and

vaccines, to shut down the invading cells before they set off

self-destruction. That remedy, it seems, is the glimmer of hope at the

bottom of this modern-day Pandora's box.