THERE might be a positive side to children who scream blue murder during immunisation 鈥� their fear of needles could make the vaccination more effective. A mouse study suggests that short-term stress increases both the strength and the duration of the immune response.
Firdaus Dhabhar and Kavitha Viswanathan at Ohio State University injected a protein called keyhole limpet hemocyanin into the skin of 20 mice. While half stayed in their regular cages, the other half were put in much smaller wire cages for two and a half hours before the injection, which is known to cause mild stress. Nine months later, when all the animals were injected with KLH again, the immune response of the second group of mice was far stronger, with more inflammation at the injection site (American Journal of Physiology, DOI: 10.1152/ajpregu.00145.2005).
Another recent study found that stressing mice by placing them in a cage with an aggressive mouse for 2 hours boosted their response to the flu virus. Dhabhar and Viswanathan think that short-term stress somehow boosts the number of immune cells called memory T-cells. They speculate that animals have a mechanism for boosting healing and the immune system after short-term stresses such as evading predators.
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In people, long-term stress suppresses the immune system, and we do not yet know whether short-term stress has the opposite effect. If it does, perhaps the prelude to vaccinations in the future will be a roller-coaster ride or a horror movie.
