Lymph node injections offer fast allergy therapy

NEW YORK (Reuters Health) - Direct administration of an allergen - the substance that triggers an allergic reaction -- into the lymph nodes, rather than the skin, reduces both the number and dose of injections required to induce tolerance to the offending substance, researchers report. This appears to offer a rapid, save and effective way to treat IgE-mediated allergies.

We demonstrated that this approach enhanced safety, efficacy, and compliance. The procedure allowed "reduction of the number of injections from 54 to 3, and reduction in the cumulative allergen dose by more than 1000-fold," Dr. Thomas M. Kundig from University Hospital Zurich, Switzerland, and colleagues write in the Proceedings of the National Academy of Science.

This type of allergen-specific immunotherapy is effective for allergies mediated by IgE, yet fewer than 5 percent of allergy patients receive immunotherapy because of its lengthy treatment and risk of allergic side effects, the researchers note.

In their study, 165 patients with grass pollen-induced rhinoconjunctivitis (hayfever and pink eye) were randomly assigned to three intralymphatic injections over 2 months of a pollen extract or to the conventional immunotherapy consisting of 54 subcutaneous injections over 3 years. The cumulative allergen dose was 3,000 standardized quality units (SQ-U) in the lymph node group versus 4,031,540 SQ-U in the conventional immunotherapy group.

According to the investigators, directly injecting the allergen into the lymph nodes was well tolerated and less painful than venous puncture according to the study subjects. It also caused fewer adverse events than did subcutaneous injections.

Moreover, within 4 months, intralymphatic immunotherapy increased tolerance to exposure to pollen, and patients in the intralymphatic group used significantly less rescue medication during the first pollen season than patients in the conventional immunotherapy group.

The intralymphatic immunotherapy relieved hay fever symptoms, reduced skin prick test reactivity and decreased blood levels of IgE.

Despite the short 2-month treatment period, tolerance was long-lasting and equivalent to that achieved after 3 years of conventional immunotherapy, Kundig and colleagues report.

The short treatment period also enhanced patient compliance; only 32 of 54 patients finished the 3-year conventional immunotherapy protocol, whereas all of the 58 intralymphatic patients received all 3 injections.

SOURCE: Proceedings of the National Academy of Science, November 18, 2008.