A study of the role of house dust mite in atopic dermatitis

Subjects with positive skin-prick tests to house dust mite (HDM) solution, including those with and without atopic dermatitis, participated in a double-blind, controlled study of the role of HDM exposure in the pathogenesis of atopic dermatitis. HDM solution and diluent control were applied daily to mildly eczematous or clinically uninvolved skin of the antecubital or popliteal fossae, without prior abrasion, for 5 days. Responses were assessed by a clinical grading system and by measurement of area of dermatitis; pruritus was recorded on visual analogue scales. The clinical grading system showed that marked or moderate delayed local reactions developed in one third of patients with atopic dermatitis in response to HDM application to both mildly eczematous and clinically uninvolved skin. Relative to control sites, significant increases in area of dermatitis and degree of pruritus were also recorded in response to HDM application to mildly eczematous sites. Application of HDM solution to normal, unabraded skin of prick test positive subjects without a history of dermatitis, produced pruritus and immediate urticarial responses which were not seen at control sites, findings which demonstrate that HDM antigen may be rapidly absorbed in normal skin. Application of vehicle or antigen solution to which subjects were negative on prick testing, produced no significant local reactions. This study provides objective evidence for a role for cutaneous HDM exposure in the pathogenesis of atopic dermatitis.