IgE Mediated Skin Test Reactivity to Indoor Allergens Correlates with Asthma Severity at Jeddah, Saudi Arabia

摘要

Background: There is an increase attention on the role of indoor allergens in asthmatics. Objective: To examine the spectrum of skin test reactivity (sensitization) to indoor allergens and its correlation with asthma severity. Methodology: Asthmatics referred to allergy clinic at King Abdulaziz University Hospital and living in Jeddah were studied. Clinical severity was determined using international and national asthma guidelines. Degree of sensitization was assessed by the wheal size (positive ≥ 3 mm) of standard skin prick test to common indoor inhalant allergens: House dust mites (HDMs): Dermatophagoides pteronyssinus (Dp) and D. farinae (Df), Cat, and Cockroach. Results: Out of 151 asthmatics, 113 asthmatics were skin test positive to one or more allergen (74.8%). Their ages ranged between 9 to 63 years (mean= 30 ±13) and females constituted 65.5%. The predominant asthma severity level was moderate persistent 55.8%, followed by mild persistent 33.6%. Prevalence of sensitization to indoor allergens was as follow: DP 87% (3 – 25 (mean = 7) mm), DF 84% (3 – 20 (mean = 7) mm), Cat 44% (3 – 15 (mean = 6) mm), and Cockroach 33% (3 – 12 (mean = 4) mm). Higher asthma severity levels were significantly correlated with the number of allergens with positive sensitization (R=0.3, P< 0.001), and the degree of sensitization to HDM Dp (df= 16, p<0.001) and Df (df=17, p<0.01), but not to Cat (df=10, p<0.24) or Cockroach (df=8, p<0.36). Conclusions: The IgE skin test reactivity to indoor allergens, particularly to HDMs, was common in asthmatics at Jeddah city. Its elevated degrees were clearly associated with higher asthma severity, which is compatible with the literature. This advocates the importance of identification of sensitization of clinically relevant allergens in asthmatics, and promotes tailored educational strategies of avoidance measures for enhanced asthma control. Introduction Asthmatic airways are characterized by an immunological chronic inflammation that has been documented to occur after exposure to allergen 1,2 . Several studies have suggested a correlation between allergen exposure and the prevalence of asthma 3,4,5 . Exposure to airborne allergens in sensitized individuals is a risk factor for asthma exacerbations, the persistence of asthma symptoms, and significant changes in the pulmonary functions 6,7,8 .Worldwide, the documented increase in the prevalence of asthma has been almost entirely in perennial asthma, and a large proportion of them are allergic to allergens found all year round in houses (indoor) 9,10 . This has lead to an increase attention on the immunological role of allergenic substances that accumulate indoors. Indoor allergens today have increased in developed countries where homes have been insulated for energy efficiency, carpeted, heated, cooled, and humidified–changes that have also made homes ideal habitat for indoor allergens 11,12 .Globally, the most abundant indoor allergens include those derived from house dust mites (HDMs), cat, and cockroach 12,13 . The principal HDM species are the pyroglyphid mites Dermatophagoides pteronyssinus (Dp), D. farinae (Dp), and others, which usually account for 90 percent of the mite species in house dust from temperate regions 9,14 . According to some local studies, similar allergens have been isolated from the indoors of asthmatics living in different regions at Saudi Arabia 15 .Recent progresses in allergy and immunology have promoted extensive studies on identification of sensitization to indoor allergens. In vivo and in-vitro allergy tests to allergen has been considered a valuable tool for exploring the presence of an IgE mediated immune response in atopic disorders, like bronchial asthma, and it is a reflection of sensitization to that allergen 16,17,18 . A direct relationship between the positive allergy skin tests or sensitization to inhalant indoor allergens and the increase in severity of asthma has been demonstrated by pervious investigators 19,20