Around Tappan Square

Go Ahead, Sweat the Small Stuff

Contrary to popular belief, some of life's heart-pounding meetings, gut-wrenching arguments, and nerve-wracking car rides could actually be good for you. A pilot study led by visiting assistant professor of neuroscience Joel Dopp and five student researchers examined the ways in which stress-inducing situations affect our body's immune system. Stress, they discovered, appears to release certain bacteria-fighting cells into the immune system--a "fight-or-flight" response that may have evolved in animals to combat infection acquired during predator/prey chases.

Senior neuroscience major Daniel Rubin, senior economics and psychology major Goldie Greenstein, senior biology major Fernando Grigera, junior psychology major Kimberly Menig, and senior biology major Stephanie L. White studied subjects' physiological responses to stress-inducing situations, keeping in mind all outside psychological variables. The results could lead to a better understanding of how acute stress can affect the immune system and impact health.

"This is a new avenue of research," Dopp says. "One that is focused on neutrophils, or white blood cells that help the body fight infection." Neutrophils, he explains, make up 65 percent of the white cells found in human blood. When a wound to the body becomes infected, the puss that forms is composed of millions of white blood cells, most of them neutrophils working to eliminate the bacteria.

In a related study as a post-doctoral fellow at UCLA, Dopp studied the physical response of married couples engaging in an argument. Subjects' heart rates and blood pressures were measured before, during, and after a 15-minute conflict. Blood samples were taken at various times to measure the fight-or-flight reactions.

Conflict, the researchers concluded, increased not only heart rate and blood pressure, but also the numbers of circulating natural killer cells, the immune system's unspecialized fighters that flood infected cells with toxins and destructive enzymes.

At Oberlin, Dopp used two laboratory stressors--mental arithmetic and vigorous exercise--to elicit the needed fight-or-flight response. He concentrated his focus on neutrophils, which are typically underrepresented in stress studies. Fifteen students completed the tasks one to two weeks apart. During one session, the students peddled on a stationary bike for 10 minutes; during another, they subtracted by sevens from 1,000 while keeping pace with a metronome that ticked every second. Blood was drawn before and after the tasks, and heart rate and skin conductance were measured throughout.

The team's findings revealed that the psychological stressor (arithmetic) caused an increase in heart rate and skin conductance that was roughly one-third the rate exhibited during the exercise stressor. Stress associated with arithmetic also increased the numbers and activity of the innate immune system cells. Specifically, subjects showed higher numbers of circulating natural killer cells and neutrophils and a higher migration of neutrophils toward bacteria. According to Dopp, these results add to a growing literature that indicates that transient stress of a mild to moderate magnitude activates the innate immune system.

Aside from its scientific importance, Dopp's study offered invaluable laboratory and analysis skills to his student team, which was encouraged to question data and suggest improvements after each trial.

"When you're in lab for a class, it's easy to let things slide," says Daniel Rubin, who processed blood samples. "But here, if we made an error, we saw it in the data that came back. This is the real world, and there are consequences. It makes you appreciate the amount of discipline and time it takes to conduct good research."

Although he laughingly referred to his job--filling half-diameter filters with purified neutrophils from blood--as "trying to do a crossword puzzle with a squirt gun," he says the experience was eye-opening and informative.

"This stress study encompassed several disciplines--immunology, neuroscience, and psychology," says Kimberly Menig, who helped analyze blood and compile data, which will be submitted for publication this spring. "All of us participated because we were interested in the subject matter. We dabbled in each other's areas while finding a balance. I also liked the fact that I really did have something to contribute. The faculty members were intent on giving us a good background."

With the pilot study complete, Dopp will investigate other questions: why people respond differently to the same stressor, if stress-reduction interventions can change one's response to stress, and at what point repeated stressors transition into immune-inhibiting chronic stress.

by Yvonne Gay

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