"Although everyday hassles such as a traffic jam or meeting a challenge at work may make you feel anxious and annoyed, these are not bad events from an immunological standpoint," says lead study author Jos Bosch, a postdoctoral fellow in oral biology at Ohio State University, in Columbus, Ohio. "A hassle a day keeps the doctor away."
Bosch and his colleagues devised tests to determine the effect of two types of short-term stress -- active and passive -- on the immune system. Active stress includes activities such as finishing a project on a tight deadline, making a big presentation at work or even scary activities such as bungee jumping, Bosch says. Passive stress happens when you have no control over the outcome, such as watching the attacks of Sept. 11 on television again and again.
Thirty-four male undergraduates were exposed to both active and passive stress. During the active stress, the students were asked to memorize a list of items and then took a timed test on the material. Those who did well were told they would win money.
In the passive stress test, the students watched a gruesome, 12-minute video on surgical procedures.
The researchers then studied the saliva concentrations of immunoglobulins, immune system proteins found in bodily fluids that make up the protective outer film of organs such as the lungs.
The proteins are deployed as part of what's called the secretory immune system, the first line of defense against pathogens trying to invade tissues.
The study found that the memory test led to an increase in the concentration of secretory immunoglobulin A, while the video had the opposite effect.
"The general public believes stress is always bad for your body, but it isn't," Bosch says. "Acute stress is mostly very good for your body."
The study appeared in the September-October issue of the journal
Researchers then measured the concentration of a molecule called secretory component, which is responsible for transporting immunoglobulins. Immunoglobulins attach themselves to the secretory components, which then carry them to the protective fluids of the secretory immune system, such as saliva.
The concentration of secretory component increased during both the memory test and while watching the video.
"In both situations, the body was producing the secretory component, trying to respond to the danger on the outside," Bosch says. "But during the passive stress, the body could not meet the demand, which is why there was less secretory immunoglobulin A in the saliva. During the active stress, there was more."
However, Sheldon Cohen, professor of psychology at Carnegie Mellon University, says studies such as this only look at a small component of the immune system and tell little about what is happening with the system as a whole.
While the levels of immunoglobulins in the saliva may indeed rise during the timed test, "it may or may not tell us anything about infectious agents in the real world," he says.
Previous laboratory experiments have shown that stress can have some positive impact on specific elements of the immune system, but in the real world, no research has shown stress makes you less likely to get sick, he says.
"The immune system is an extra-complex and dynamic system," Cohen says. "Ultimately, you have to look at disease outcomes."
What To Do
This short-term, or acute, stress looked at in this study should not be mistaken for chronic stress, which doctors believe harms the immune system's ability to fight off viruses and bacteria.
For tips on coping with stress, check this University of North Carolina Web site, the Job Stress Network or the National Institute for Occupational Safety and Health.