Perfil de reatividade de anticorpos IgE, IgG1 e IgG4 ao alérgeno recombinante Blo t 5 de Blomia tropicalis e sua forma modificada em pacientes atópicos e não atópicos

Abstract

Exposure to house dust mite (HDM) allergens is the main risk factor for the development of respiratory allergy. Blo t 5 is the most important allergen from the mite Blomia tropicalis (Bt) and at least 70% of rhinitis patients show IgE reactivity to this allergen. The aim of this study was to evaluate the IgE, IgG1 and IgG4 reactivity profile to recombinant Blo t 5 allergen and its modified form in atopic and non-atopic patients. Three patient groups were evaluated (atopic Bt+, atopic Bt- and non-atopic) with basis on the skin prick test and serological assays. We designed two constructs encoding the Blo t 5 full sequence, one with the original sequence (rBlo t 5) and another with a modified sequence (mBlo t 5) and produced the respective recombinant allergens. The specific reactivity of rBlo t 5 and mBlo t 5 was probed with the monoclonal antibody to Blo t 5 and positive IgE serum from atopic Bt+ patients in slot-blot assays. IgE levels and positivity to both rBlo t 5 and mBlo t 5 were comparable in atopic Bt+ patients. A similar profile of IgG1 reactivity to recombinant allergens was found in both atopic and non-atopic patients. It was notable an increased IgG4 reactivity to mBlo t 5 in relation to rBlo t 5 in atopic Bt+ patients. There was a positive correlation between IgE and IgG4 to both recombinant allergens and rBlo t 5 was preferentially recognized by IgG1 and IgG4 than IgE antibodies, being this phenomenon more evident for IgG4 to mBlo t 5. The IgE reactivity reduction occurred in 48% of samples and 26% of them had a significant reduction (>20%). In relation to IgG4 reactivity, 57% of samples presents an increase, and 37% of them presents an increase >20%. In conclusion, the modified Blo t 5 allergen showed a shift of antigenicity for the IgG4 isotype, thus making suitable its use as potential candidate in specific allergen immunotherapy practice studies.