Under-tongue therapy may ease bee-sting allergy

NEW YORK (Reuters Health) - For people who are strongly allergic to bee venom, desensitization using sublingual (i.e., under-the-tongue) immunotherapy may be a safer than injection immunotherapy, according to a proof-of-concept clinical trial conducted in Italy.

“Our research opens a new possible application of sublingual immunotherapy, which was never proposed for hymenoptera allergy,” Dr. Giovanni Passalacqua told Reuters Health.

The standard way to desensitize patients with bee sting allergy is to administer small, increasing doses of venom by subcutaneous injections. However, there is a “particular risk of systemic/severe reactions” with this approach, the research team notes in the Journal of Allergy and Clinical Immunology.

On the other hand, they say, “systemic side effects are rare, severe adverse events are exceptional, and the common local side effects are mild and self-limiting” with sublingual immunotherapy, or SLIT.

To evaluate SLIT’s suitability for hymenoptera allergy, Passalacqua, at the University of Genoa, and his associates conducted a trial involving patients who had experienced large local reactions -- swellings of 10 centimeters or more lasting more than 24 hours -- to bee stings.

Venom extract was administered under the tongue daily, starting with a tiny amount and building to bigger doses over 6 months. The trial was completed by 14 patients randomly assigned to SLIT and 12 assigned to placebo.

The maximum diameter of the local reaction when participants were deliberately exposed to a “challenge” sting was significantly reduced only in the active treatment group, the investigators report.

SLIT with honeybee venom was well tolerated, the report indicates, with no adverse events or discomfort reported by the subjects.

“Other studies are currently ongoing to better define the mechanisms of action of SLIT, and to assess its safety when multiple allergens are used in the same patient,” Passalacqua noted.

SOURCE: Journal of Allergy and Clinical Immunology, July 2008.