Developments in Brief : Salmon Offers Clue on Stress, Immune System
Oregon State University scientists who have been studying the Pacific salmon have found a biochemical explanation for how stress may weaken a key part of the immune system in both fish and humans.
The research was done with laboratory and field studies in the Pacific Northwest. The studies could lead to improved survival rates for fish in a stressful hatchery environment--as well as to new insights into human immunology.
The work, soon to be published in a professional journal, outlines for the first time the exact cellular mechanisms that are involved in one type of suppressed immune response.
An immune response, in both fish and humans, is often a combined reaction of two types of white blood cells, called “T” cells and “B” cells, according to Stephen Kaattari, an assistant professor of microbiology at Oregon State. The recent research explains the exact way in which stress can prevent the “B” cells from becoming activated to do their job.
The action of the “B” cells is triggered by a “message” from a third type of cell called a macrophage, Kaattari said. This message is delivered by a small protein called an interleukin, he said.
When the animal is undergoing intense emotional or physical stress, a steroid called cortisol is produced at high levels. The rising levels of cortisol interfere directly with the production of the “messenger” interleukin. And if the message to produce antibodies is not passed along, one important part of the immune response is dramatically reduced.
“An effective immune response varies a lot, depending on which agent is attacking the system,” Kaattari said. “Sometimes it calls for a response by ‘B’ cells, sometimes by ‘T’ cells and sometimes by both. But with the rising levels of cortisol, there is a drop in ‘B’ cell immune response.”
“It’s long been known that physical and emotional stress can weaken the immune system in humans, fish or other vertebrate animals,” Kaattari said. “But we didn’t really understand the cellular and molecular reasons for this. Our knowledge of that process is now more comprehensive.”
