Temporal association between Der pI exposure, immediate hypersensitivity and clinical severity of eczema

Uncontrolled studies of avoidance of house dust mite (Dermatophagoides pteronyssinus) by atopic subjects have reported clinical improvement in the severity of eczema. The aim of the present study was to examine the temporal relationship between environmental exposure to the major mite allergen (Der pI) and clinical disease severity in children with chronic atopic eczema. Twelve children were identified as being house dust mite-sensitive on the basis of skin prick test and RAST to Der pI. They were examined on two occasions with a median interval of 63 days. Clinical severity of eczema improved in nine children and deteriorated in two children during this period. Der pI concentration in dust from mattresses changed significantly in only three subjects and there was no correlation between changes in clinical severity and changes in environmental Der pI exposure. Change in RAST against Der pI did correlate positively with change in Der pI exposure (rho = 0.56, P less than 0.05) but these changes were not associated significantly with changes in eczema severity or skin test response to Der pI. It is concluded that the observed changes in clinical severity were unlikely to be due to immediate hypersensitivity responses to natural variations in Der pI concentrations in the personal environments of these subjects.