Allergy and irritation: an adverse association in patients with atopic eczema

The pathomechanism of atopic eczema is complex. Two of the most important exogenous factors for atopic eczema are allergenic and irritant substances. In this study we investigate the combined effect of topical aeroallergens and irritation on the skin of atopic individuals. We performed patch testing with several aeroallergens (atopy patch test) and with an irritant, sodium lauryl sulphate, on clinically unaffected skin of 30 sensitized patients with atopic eczema. Application was conducted alone and as a consecutive application. Healthy volunteers served as controls. Evaluation was made by measurement of transepidermal water loss 2 h after removal of the patches. In atopic patients, we found increased levels of transepidermal water loss induced by the aeroallergens as well as by sodium lauryl sulphate. The most impressive barrier disruption was seen after application of house dust mite, followed by cat dander and grass pollen. However, the consecutive application of aeroallergens and sodium lauryl sulphate led to a highly pronounced increase in transepidermal water loss. Hence, in sensitized atopic subjects the combined effect of aeroallergens and detergents may cause severe skin problems, and this may be relevant in daily practice.