Whenever a co-worker has a bad cold, Karen Edelblum wears a mask.

She has sworn off raspberries and popcorn.

And, although just in her mid-30s, she already has been through a case of shingles, a disease that more typically strikes those over 50.

Such is life for someone with Crohn's disease, a misery-inducing immune disorder with flare-ups that she likens to having food poisoning for months on end.

But unlike most of the 1.6 million others in the United States who suffer from inflammatory bowel disease, which includes Crohn's and colitis, Edelblum is fighting the problem not only as a patient, but also as a scientist.

An assistant professor at Rutgers New Jersey Medical School, she has uncovered new clues about specialized cells in the immune system, ingeniously recording microscopic movies of their activity inside a live mouse.

Edelblum also is active in the patient community, having worked nine summers at a camp for children with the condition, and raising money for research. All the while she maintains a sense of humor about a disease marked by severe diarrhea. (The name of her team in a recent fund-raising walk? Two-Ply Minimum.)

She gets high marks from former boss Jerrold R. Turner, a senior pathologist at Brigham and Women's Hospital in Boston.

"She's really the full package," said Turner, a faculty member at Harvard Medical School. "She's not somebody who's going to go into her lab and close the door."

It was a course that Edelblum started plotting when she was 13 years old.

An initial misdiagnosis

That's when the first flare-up happened.

Like others with her condition, Edelblum has a "leaky" gut - a flaw in the lining that separates the intestinal tract from the bloodstream.

But that alone is not enough to cause colitis, which strikes the colon, or Crohn's, which can occur anywhere in the digestive tract.

Sufferers also have an immune system prone to going into overdrive, so that when bacteria invade, the immune response sets off a vicious cycle of inflammation, leading to further impairment of the intestinal lining.

It is unclear what triggers a flare-up, though stress can contribute. Physicians sometimes fail to read the signs.

Edelblum had a chronic fever and gastrointestinal distress, and one internist suggested she might have leukemia. Her mother was skeptical and sought another opinion, eventually getting a diagnosis of Crohn's.

The 13-year-old patient then asked her doctor three questions: Am I going to die? (Not from this.) Is there a cure? (No.) If I have kids, would they get it? (Possibly.)

"That's when I decided this is what I'm going to do with my life," she recalled last month, sitting in her lab in Newark, N.J. "If I have the capability to change this outcome for myself or others, then why not do that?"

Growing up in the Houston area, she always had been interested in science. When peers recoiled from dissecting worms and other creatures in science class, she would offer to come in early and do it for them.

She studied biology as an undergraduate at Emory University, followed by a doctorate in cell biology at Vanderbilt University and a post-doctoral position with Turner, then at the University of Chicago.

Edelblum was far from the first patient who aspired to study her own disease, Turner said.

"What's unusual is that she followed through, and she didn't change her mind later," he said. "What most people in the world don't realize is how hard research is."

Mouse movies

Working with Turner, she used sophisticated microscopes to peer inside the gut of a sedated mouse, carefully performing surgery to ease the animal's intestines onto a glass plate without disrupting their function.

Sitting in front of a computer screen at Rutgers, she called up a series of images recorded through that procedure, revealing the activity of a poorly understood immune soldier called a gamma delta T-cell.

Highlighted in fluorescent green, the cells can be seen approaching the lining of the animal's intestine. They remain in position for a few minutes, then retreat and move to another location, a pattern that made Edelblum think of a sentinel on patrol.

Last year in the journal Gastroenterology, she, Turner, and colleagues reported that these sentinels appear to serve an antibacterial function.

The team administered Salmonella bacteria to two kinds of mice: one in which the movement of these sentinels was genetically blocked, and another in which it was enhanced.

"If you block the migration of these cells, more bacteria get in," Edelblum said. "And if you enhance the migration, fewer of them get in."

Other researchers have shown that the cells secrete an antimicrobial peptide, though it is not clear that is what keeps the bacteria from getting across.

These sentinels are not compromised in people with Crohn's or colitis, Edelblum said. Rather, she hopes there might be a way to enhance their activity to strengthen a patient's defenses against the disease.

They appear to be among the immune system's first lines of defense, springing into action long before inflammation sets in.

She is intent on finding what causes the sentinels to migrate. Some signal from the bacteria, perhaps.

For now, Edelblum keeps her own disease at bay with immunosupressive drugs, receiving intravenous infusions every 10 weeks. With careful management of her disease, she has not had a flare-up in 14 years.

But the suppressed immune system led to the case of shingles a few years ago, and it makes her wary of sneezing coworkers. And past flare-ups have left her with lesions in her colon, hence the need to avoid popcorn and raspberries - too irritating.

She continues to advise others with inflammatory bowel disease, and in one case went a step further, inviting a patient from the summer camp to come work with her for a few months.

The microscopic sentinels on her computer screen may not end up holding the answer. But Edelblum is determined to serve as a human sentinel so long as the disease poses a threat.