Background
Allergen immunotherapy (AIT) has been around for over 100 years, and plenty of advances have occurred since the first report of successful grass pollen immunotherapy in 1911.[1] Several studies and meta-analyses support the efficacy of both subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) for allergic rhinitis and asthma.[2]
One of the great advantages of AIT is that this immunomodulatory treatment may have an enduring benefit long after AIT is discontinued. One of the disadvantages of AIT, however, is that it is not always effective. We have no tools at our disposal to routinely predict response.
Given the commitment of resources, time, and money for doctors, insurers, and patients, a marker for predicting AIT responsiveness is desirable. With the recent focus on personalized medicine, it seems to be the right time to find a strategy for predicting response to AIT.
Improvement in respiratory allergy symptoms correlates with the shift from T-helper 2 to T-helper 1 cytokine profiles and from immunoglobulin E (IgE) blocking by immunoglobulin G4 antibodies.[1] Even though symptoms may improve early on during the course of AIT, immunologic changes and maximal improvement do not often occur until the second year of AIT.
Predicting Response to AIT
A few trials have looked at factors differentiating AIT responders.
