الفهرس 
ِAcknowledgementOnly 14 pages are availabe for public view
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Abstract
House dust mites are very important indoor allergens worldwide. Continuing research on prevalence of house dust mites will help in identification of the magnitude of the problem in a certain locality. It can also improve implementing appropriate investigations and diagnostic tools that in turn gives a better quality of life of allergy sufferers worldwide.Our study aimed to identify and characterize the common species of house dust mites collected from different areas in Assiut city, studying their seasonal variation, and effects of some housing criteria on their prevalence. Also the study aimed to detect the sensitivity of preschool children aging from one to five years to common House dust mites species Dermatophagoides pteronyssinus and Dermatophagoides farina and to investigate both allergen composition and screening of antibody specificities in children with bronchial asthma by Immunoblot test done between House Dust Mites-allergen and specific antibody. The prevalence of house dust mites in studied samples was 31.3 %. Seasonal variations significantly affected the frequency of house dust mites, the highest frequency was noticed during winter (66.7%) and the least frequency was noticed during summer (13.3%). The most frequently isolated species were Dermatophagoides farinae (80.9%) and Dermatophagoides pteronyssinus (58.5%) followed by stored products mites, Tyrophagus putrescentiae (50%) and predatory mites, Cheyletus malaccensis (31.9%). Some housing criteria: age of the house, damp or mouldy stains on floor or on other indoor surfaces, presence of carpets/rugs and aeration style have significantly affected the prevalence of house dust mites. We concluded that although Assiut is the driest city in Egypt with low relative humidity (according to the climatic classification system), there is un-neglected prevalence of house dust mite (31.3%). Possible explanation could be that indoor humidity suitable for mites’ presence are achieved by household populations who tend to stay at home for long periods, and over crowdedness especially in bedding areas. Skin prick test was done on the preschool children using D. pteronyssinus and D. farinae antigen extracts and it detected 65 (65%) cases who reacted positive to D. farinae extracts while 63 (63%) cases positive to D.pteronyssinus extract. The electrophoresis of Dermatophagoides farinae revealed three polypeptide bands, whose MW ranged from 45 to 62 kDa. These bands were corresponding to MW of 45, 55, 62 kDa. Western blotting of Dermatophagoides antigens showed that pooled human sera presumptively containing IgE antibodies against the HDM D. farinae recognized one band of MW ≈ 62 KDa. So the study suggested that 62 KDa polypeptide band of HDM D.farinae is the major allergen found in Egyptian preschool children with recurrent wheezy chest attending Assiut University Pediatric Hospital.