THE ROLE OF HOUSE DUST AND HOUSE DUST MITE IN ATOPIC DERMATITIS

Abstract

AD is a common, chronic inflammatory disease of increasing frequency. No single cause can be incriminated in AD, but the HDM is known to be the most common exogenous etiologic factor in the pathogenesis of AD. Therefore, the aim of this work was studying the role of the HD and the HDM in producing type I, type IV or both types of hypersensitivity skin reactions in AD patients. Thirty AD patients and ten apparently healthy control subjects were recruited from Ain Shams University hospital. They were subjected to a detailed history taking, as well as a general and dermatological examination. A blood sample was obtained to estimate the total and the specific IgE level to the HD and the HDMs, Dermatophagoides pteronyssinus (Dp) and Dennatophagoides farinae (Df). Patients and controls were also subjected to a SPT and an APT to Dp, Df, and HD. A skin biopsy was taken from positive APT sites and histopathologic examination was done to determine whether the skin response was due to type I (LPR) or type IV hypersensitivity reactions. ., The different tests were studied in relation to each other, and also in relation to the age and sex of the patients, the severity of the disease, the presence of personal history of exacerbation of AD after the exposure to HD, the presence of personal history of ARD and the family history of atopy. The concentrations of allergenic extracts of the HD and HDMs used in the APT were studied in relation to the intensity of the skin reactions they produced. Histopathologic examination of the skin biopsies taken from positive APT reactions was performed.