Pollen Used to Make a Vaccine Against Hay Fever

A six week treatment with a new vaccine can reduce hay fever symptoms by 60% for at least two years, avoiding meanwhile the secondary effects of the steroids currently used to cure allergies.

This is much faster than pollen injections, which provoke the desired reaction in the immune system over a course of several years. "It is the first time the approach has been applied to this disease," says Toshiaki Kawakami at La Jolla Institute for Allergy and Immunology in California, US.

"It could offer a much needed alternative for patients who fail to respond to conventional therapies, such as antihistamines to control their allergic response," Kawakami says.

Around 40 million people in the US suffer from seasonal allergies (hay fever) caused especially by pollen granules floating in the air during the springtime and which, at the contact with the human organism, provoke a powerful immune reaction. The body starts producing excessive amounts of the immune chemical histamine that lead to the characteristic hay fever symptoms, such as itchy eyes and sneezing.

The vaccine, called AIC, uses a short sequence of DNA, known as an "immunostimulatory sequence", which stimulates the immune system response. The DNA sequence is attached to the protein in ragweed pollen (photo), which is one of the main causes of the seasonal allergies in the US. This DNA sequence has a special affinity for the receptors on outer cells in the mucosa respiratory mucosa (dendritic cells).

The vaccine formed by DNA and pollen bind to the dendritic cells result a chain of physiological reactions with the final result being less immune proteins and, of course, a lower amount of histamines to cause the allergy symptoms associated with hay fever.

As already mentioned, the patients who received the vaccine reported 60% fewer days with severe allergies, compared to counterparts who received placebo injections. The effect to allergies was equally strong in the second year for those who had been given the vaccine a year before, even though they received no further vaccine in the second year.

The scientists did not monitor further the condition of the patients after 2002, but there was evidence that the response lasts longer.

Unlike allergens containing vaccines, this vaccine seems to produce no allergic reactions.