Improving pollen immunotherapy: minor allergens and panallergens.

Multiple sensitizations to pollens are common clinical situations in Spain, and alter the efficacy of allergen-specific immunotherapy. We now know that optimization of the diagnosis is required to define the best suited treatment for each patient. All pollen allergens belong to 29 families of proteins - the most abundant being the expansins, prophyllins and polcalcins. The ubiquitous nature of proteins such as the prophyllins and polcalcins defines them as panallergens, and explains the cross-reactivity that is erroneously interpreted by clinicians as constituting multi-sensitization. Other families of allergens, such as the calcium transporting proteins (LTPs) are more restricted, but are associated to severe types of allergic disease - this being particularly useful to decide upon the indication of immunotherapy. Although recombinant allergens can be produced for in vitro diagnostic purposes, current legislation only allows the use of natural proteins for immunotherapy. However, the same technology can be applied to the study of extracts for vaccines, and it seems that allergen quantification by the manufacturers is a no return trip which clinicians are obliged to follow.