House dust mite antigen exposure of patients with atopic dermatitis of psoriasis.

We studied the amount of house dust antigen in the beds of 55 patients with atopic dermatitis, eleven patients with psoriasis and ten healthy volunteers using a commercial ELISA which can determine the amount of antigen from Dermatophagoides pteronyssinus, D. farinae and D. microseras expressed as nanogram (ng) antigen per gram of house dust. The World Health Organization has indicated that 10,000 ng house dust mite antigen per gram house dust can elicit an asthma attack in IgE-sensitized patients with asthma bronchiale. There are no recommendations for patients with atopic eczema. We observed no statistical significant differences between each group concerning the amount of house dust found in the beds or the amount of house dust mite antigen. However, there were very wide variations. Twenty-seven percent (15/55) of patients with atopic dermatitis and 27% (3/11) of psoriasis patients had levels of house dust mite antigen above 10,000 ng per gram of house dust compared with healthy volunteers (1/10). Half of the patients had a type I allergy to house dust mite antigen using prick tests. This group had a total serum IgE of 2,034 kU/I (median value) compared to 301 kU/I in the group without type I allergy to house dust mite antigen (p < 0.01). The exposure to house dust mite antigen was similar in the two groups. We conclude that only 1/4 of patients with atopic dermatitis are exposed to high levels of house dust mite antigen in their bed environment equal to what is found for patients with another scaling disorder (psoriasis). Patients who have an increased serum IgE have significantly increased type I allergy to house dust mite antigen even though their exposure is not different from patients with low IgE.