Allergy injections?

13 November 2008


Do you have hay fever? I do, and it's a right pain in the nose every year. Now there may be help for hay fever sufferers in the form of an injection right into the lymph nodes.

PollenHay fever and similar allergies are caused by the body mounting an excessive immune response to harmless particles in the air, including pollen, dust and so on, and they affect around a third of people in Western countries. Many people get relief from antihistamine tablets that damp down the response.

But for people with severe hay fever that's not enough. Instead, they can be offered allergen immunotherapy - injections of large doses of the allergens they respond to.  It's pretty nasty stuff though, and can cause dangerous reactions. It also takes up to 70 visits to the doctor over 5 years.

Now, Gabriela Senti and her colleagues from University Hospital Zurich have found a new way to deliver this immunotherapy - by injecting the allergens directly into the lymph nodes. These are the parts of the immune system where immune cells hang out, and where foreign particles are trapped, as well as allergens that have travelled in the bloodstream after an injection as part of regular allergen immunotherapy.

To test the technique, the team ran a clinical trial of about 110 hay fever sufferers, who were split into two groups. The first group got the standard treatment of more than 50 injections under the skin over 3 years. But the second group got just three injections into their lymph nodes in their groin, over 8 weeks.

 After just four months, the group who'd been injected in their lymph nodes were about 10 times less sensitive to pollen than they had been before. But the group on conventional treatment took a whole year to show improvement, and had to resort to taking antihistamines much more often. The new treatment also lasted just as long as the standard skin injections, and the people given lymph node injections had fewer side effects, and no serious reactions.

The new technique means many fewer injections, and a much smaller total dose of allergen. Not only is this much nicer for the patient, and presumably cheaper, it's also safer.  Now we just have to wait and snuffle until it's commercially available.


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