Lack of neo-sensitization to Pen a 1 in patients treated with mite sublingual immunotherapy

The aim of this study was to evaluate the development of neo-sensitization to Pen a 1 (tropomyosin) as well as the appearance of reactions after ingestion of foods containing tropomyosin as a consequence of sublingual mite immunization.Specific IgE to Tropomyosin (rPen a 1) before and after mite sublingual immunotherapy in 134 subjects were measured. IgE-specific antibodies for mite extract and recombinant allergen Pen a 1 were evaluated using the immunoenzymatic CAP system (Phadia Diagnostics, Milan, Italy).All patients had rPen a 1 IgE negative results before and after mite SLIT and did not show positive shrimp extract skin reactivity and serological rPen a 1 IgE conversion after treatment. More important, no patient showed systemic reactions to crustacean ingestion.Patients did not show neo-sensitization to tropomyosin, a component of the extract (namely mite group 10) administered. An assessment of a patient's possible pre-existing sensitisation to tropomyosin by skin test and/or specific IgE prior to start mite extract immunotherapy is recommended.This trial is registered in EudraCT, with the ID number of 2010-02035531.In developed countries respiratory allergy is an important cause of chronic illness [1] and has a significant socio-economic impact [2]. As stated in consensus documents, allergen specific immunotherapy (SIT) is the only curative approach to treat respiratory allergic diseases [3,4]. As a matter of fact, commercial extracts used for SIT contain all or almost all the sensitizing molecules, including major and minor allergens, whereas patients receiving the treatment may be sensitized to only some of them. This raises the question of whether the administration of allergen extracts during immunotherapy can induce new clinically relevant sensitizations [5], that is the appearance of IgE specific for other allergenic molecules. Some studies have, in fact, reported the development of new sensitizations to allergenic components during subcutaneous immun