Sensibilização e exposição a alérgenos de ácaros domiciliares entre pacientes asmáticos de Uberlândia, MG

Abstract

Mites of the family Pyroglyphidae (Dennatophagoides spp.) are the major source of allergens in house dust. The association between exposure and sensitization to mite allergens in the development of allergic diseases, particularly asthma, has been recognized in several parts of the world. Previous studies performed in Brazil have shown that D. pteronyssinus (Dpt) and B. tropicalis are the most prevalent mite species while D. farinae is rarely found. The aims of this study were to evaluate the sensitization and the exposure to the Der p 1, Der p 2, and Der f 1 allergens among asthmatic patients and non atopic subjects living in Uberlândia as well as to investigate the correlation between exposure indexes to these allergens and sensitization. A total of 89 asthmatic patients was submitted to skin prick test (SPT) for Dpt and divided in the groups SPT + (n = 48) and SPT - (n = 41) in addition, 26 non—atopic subjects were included. Sensitization was evaluated by measuring the levels of serum specific lgE (≥ 3.9 EU/mL) to the Der p 1, Der p 2, and Der f 1 allergens by reverse ELISA. Allergen exposure was evaluated by measuring the levels of these allergens in the house dust by two—site monoclonal antibody ELISA. Sensitization among asthmatic patients (SPT + and SPT -) to Der p 1, Der p 2, and Der f 1 allergens was about 38%, 37%, and 34%, respectively. Among SPT+ asthmatic patients, sensitization to Der p 1 Der p 2, and Der f 1 allergens was 68.8%, 68.8% and 60.4%, respectively, presenting specific IgE mean levels of 24.7, 28.4 and 19,7 EU/mL, respectively. ln contrast, no sensitization to these allergens was found in the vast majority (96% to 100%) of the SPT asthmatic patients and non—atopic subjects. The highest levels of allergens were found in bedding samples, with mean levels of 3.0, 3.6, and 17.1 µg/g of dust for Der p 1, Der p 2, and Der f 1, respectively in the asthmatic patients' homes. Considering levels ≥ 2µg/g of dust (risk factor for sensitization), exposure indexes among SPT+ asthmatic patients were 75% (Der p 1), 70.8% (Der p 2), and 87.5% (Der f 1), while 23.1% (Der p 1 and Der p 2 and 84.6% (Der f 1) were found in the non asthmatic group. Considering levels ≥ 10 µg/g of dust (risk factor for exacerbation of asthma symptoms), the highest exposure indexes among SPT+ asthmatic patients were 50%, 45.8% and 75% for Der p 1, Der p 2, and 1Der f 1, respectively, unlike the non-asthmatic subjects that presented lower exposure indexes (0% for Der p 1 and Der p 2, and 23.1% for Der f 1). No significant correlation was observed between the levels of serum specific IgE and the allergen exposure index. The high levels of the Der p 1, Der p 2, and particularly Der f 1 allergens in the analyzed house dust samples showed that the mites D. pteronyssinus and D. farinae are important in the sensitization and allergen exposure among asthmatic patients living in Uberlândia. These results allow to conclude that the knowledge of the regional mite fauna will certainly contribute to better investigate the association between allergen exposure and sensitization. This fact will allow that is established the necessity of including new mite extracts in inhalant skin test sets used for evaluating patients with suspicious respiratory allergy, to elaborate indoor allergen avoidance in order to reduce exposure to and mites as important part of the global therapeutic strategies for the management of the allergic patient.