The hygiene hypothesis has been proposed as an explanation for why the incidence of allergies is increasing in western countries. This solution explains how allergies arise, summarizes the hygiene hypothesis and details possible mechanisms why it may lead to more allergies.
Allergies are the result of a misdirected immune response against an innocuous substance. The CD4 arm of the T cell response can mount two types of response - termed Th1 or Th2, the latter being associated with allergies. In a Th2 response there is production of the cytokines interleukin-4 and -5, which promote production of immunoglobulin E (IgE). This type of immunoglobulin is adapted to counter large ...
The incidence of allergies, particularly asthma and food allergies, has been rising dramatically over the last ten years. However this has occurred mainly in Western countries but not the developing world. This has lead to the hygiene hypothesis, which connects the overall level of hygiene with the risk of developing allergies. This solution explains the hygiene hypothesis, the development of allergies and possible mechanisms responsible.