Exam nerves affects students' immune defence

22-Aug-2006

While diseases like asthma and allergies are becoming increasingly common in the West, many people believe that we are living ever stressful lives. A new study from Karolinska Institutet backs up what many people have suspected: that there are important links between mental stress and the complex physical inflammation reactions characteristic of allergies.

In order to understand the link between stress and allergy, the scientists have examined how a major medical exam at Karolinska Institutet affects feelings of stress, stress hormone levels, the immune system and lung function amongst students with and without allergies. The extensive tests were made on two occasions, first with the students during a calm period of study with no exam in sight, and then shortly before a major exam. Twenty two students with hayfever and/or asthma and 19 healthy students took part.

For the first time on record, scientists were able to show that a group of cells that are central to the human immune system known as regulatory T cells appear to increase sharply in number in response to mental stress. A regulatory T cell is a kind of white blood cell that controls the activity of a number of other types of immune cell. This increase was observed in both groups of students.

The study also showed that blood concentrations of a group of inflammation products called cytokines had changed and shifted against a pattern associated with allergic inflammation in the allergic students, but remained normal in the healthy students. According to Mats Lekander, who is leading the research group, the two discoveries might very well be linked.

"There is much to suggest that the regulatory T cells are dysfunctional in people with allergies," he says. "When people become stressed, they increase in number and normally have an anti-inflammatory effect. If this system does not work in people with allergies, it could explain the changed cytokine balance that we have observed in them."

Original publication: C. O. Höglund, J. Axén, C. Kemi, S. Jernelöv, J. Grunewald, C. Müller-Suur, Y. Smith, R. Grönneberg, A. Eklund, P. Stierna, M. Lekander: ""Changes in immune regulation in response to examination stress in atopic and healthy individuals"; Clinical & Experimental Allergy 2006, 36 (8), 982-992.

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