The challenge of primary and secondary prevention of atopy and asthma has stimulated a variety of prospective interventional trials that are currently ongoing all over the world. Unfortunately, pharmacotherapeutic trials that aimed at long-term disease modification with an inhaled corticosteroid, or prevention of asthma in children with atopic dermatitis by giving an H1-antihistamine such as cetirizine or levocetirizine, have failed to provide more than symptomatic relief during treatment.
A long-term prevention study with a calcineurin inhibitor is currently underway. On the basis of encouraging animal studies, avoidance studies including elimination of alimentary proteins as well as indoor allergens or tobacco smoke, and intervention with oral application of endotoxin, or exposure to mycobacteria or parasites are being conducted. Finally, trials aimed at nonspecific or specific induction of tolerance have recently been initiated.
Allergy immunotherapy has been based on antigen-specific stimulation of the adaptive immune system (by subcutaneous or sublingual specific immunotherapy) for a century. However, the most recent evolution modified our immune system in such a way that allergy is no longer the rare exception but is becoming increasinglym prevalent. Factors once abundant in our environment that normally stimulated our innate immune system to protect us from allergy development are now missing more and more often. Several categories of new intervention strategies for allergy prevention are based on this concept: induction of immune functions that are able to down-regulate unwanted immune responses against allergens and suppressm allergen-induced inflammation. These new preventive and therapeutic strategies are not limited to respiratory allergies, but involve food allergies as well.