Hey Fever! The Surprise Benefit Of Allergies

There have already been indications that people with strong allergic responses might be more resistant to parasites, and that the paucity of parasites in modern life causes an increase in allergies. This is because the part of the immune system that would otherwise be occupied fighting parasites doesn't have enough real threats to keep it occupied, and so "fights" normally harmless allergens.

http://www.sciencedaily.com/releases/2008/07/080729133643.htm

ScienceDaily (July 30, 2008) — Long-suffering victims of allergies such as asthma and hay fever might enjoy a surprise benefit, according to research led by the University of New South Wales (UNSW).

In a paper presented at an international symposium in Sydney, the researchers show that people with one of these atopic diseases are up to 25 percent less likely to get the most common type of Non-Hodgkin Lymphoma (NHL).
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The more atopic diseases the individual has, the less likely they are to succumb to NHL. If an individual has three of these conditions, they are 40 percent less likely to get NHL.

Having had asthma and hay fever for a long time, also appears to be of greater benefit.

The result is significant given that the incidence of NHL in developed countries has escalated dramatically in the past 50 years. It is three times more prevalent now than it was in 1950, making it the sixth most common cause of cancer death in Australia, yet the cause of most cases remains unknown.

"This was a surprise result," said the lead author, Dr Claire Vajdic. "The only known strong risk factors for NHL are immune deficiency and certain infections. This occurs in people with uncontrolled HIV infection, and those who have had a solid organ transplant.

"So we thought other forms of immune dysregulation such as atopic diseases – including hayfever, asthma and food allergies – might relate to the development of lymphoma. It was therefore intuitive to think that these conditions would increase the risk, but in fact, they do the reverse," she said.

The research found that risk was reduced in B-cell NHL only. This is the most common type of NHL.

"While the relevant biological mechanisms are not yet known, the pooled data indicate that chronic and multiple atopic conditions impart the greatest reduction in risk," said Dr Vajdic. "Investigation of the genetic and environmental factors underlying atopy and the apparent inverse effect of atopy on NHL risk will inform our understanding of the complex biological pathways that may be involved."