Renegade Germ Fighters May Raise Stroke Risk

But there's nothing you can do to head them off, says study

WEDNESDAY, Aug. 15, 2001 (HealthDayNews) -- Scientists have discovered that an older man's risk of heart attack or stroke will double if his immune system creates a kind of renegade germ fighter. But don't ask your doctor for the necessary blood test just yet. It's far from clear how this knowledge will help patients.

"The problem is that we haven't found any sort of dietary or medication intervention that would lower the person's risk," says Dr. Robin L. Brey, professor of medicine at the University of Texas Science Center.

Brey and other researchers studied 1,993 Japanese-American men who took part in a Hawaiian medical study for than 20 years. Of the men, 259 suffered an ischemic stroke (caused by a blockage in a blood vessel) and 374 suffered heart attacks. Their findings are in the latest issue of the journal Stroke.

Blood tests taken before the men were stricken showed they were more likely to have levels of a kind of germ fighter known as beta-2 dependent anticardiolipin antibodies. About 17 percent of those who had a stroke and 16 percent who had a heart attack had the antibodies. Only 12 percent of men with no cardiovascular disease had the antibodies.

"Antibodies are proteins made by the immune system that normally are a good thing," Brey says. "They normally fight off infections and cancer cells, any kind of foreign organism or cell that's in the body."

The antibodies work by "tagging" invading cells that spell trouble, letting the immune system know that they're there, she says.

But sometimes the antibodies, either through poor programming or confusion, start targeting the body's healthy cells. Then the body may develop a debilitating auto-immune disease like lupus in which the body basically destroys itself.

Data on the men with antibodies when they reached ages 60 to 70 showed their annual risk of heart attack or stroke rose from an expected 1 to 2 percent to 2 to 4 percent, depending on what other risk factors were present, Brey says.

Researchers don't know why the antibodies and cardiovascular disease were linked, but they have theories. "We think that [the antibodies] are involved in setting off kind a chain of events that leads to blood clot formation," and clots --- roadblocks in the circulatory system --- can lead to heart attacks or strokes, Brey says.

The antibodies may raise the risk of clots by raising havoc in the lining of blood vessels and making them more "sticky," Brey says.

But while simple blood tests can detect the presence of the troublesome antibodies, the germ fighters aren't a "smoking gun" that directly causes a stroke or heart attack in all cases, says Dr. Steven Kittner, professor of neurology at the University of Maryland School of Medicine and an author of the study.

Instead, the antibodies appear to be yet another risk factor, just like clogged arteries or high blood pressure, that raises the possibility of a problem, he says.

Kittner says he isn't sure what someone with the antibodies should do. "It's not known whether people with these antibodies should be treated differently. That's still being studied," he says.

In fact, doctors usually don't test for the presence of antibodies in people who haven't already had strokes because the information ordinarily would not be helpful, says Dr. Ralph L. Sacco, an associate professor of neurology at Columbia University.

What To Do

Unless you've had a stroke or heart attack, doctors say there's no reason to get a blood test to see if you have the suspect antibodies because no treatment plan is available. The best ways to avoid a stroke or heart attack are to watch your diet, exercise and let your doctor monitor your vital signs.

Also, this study only looked at Japanese-American men; these results may not apply to women or men of other descent.

What is an antibody? The University of Kansas will tell you in this light-hearted Web page.

Learn more about heart attack and stroke from American Heart Association fact sheets.

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