Changes in Histamine/Tryptase Levels in Skin Chambers: Application for Clinical Evaluation of Atopic Dermatitis

We measured changes in histamine and tryptase levels in fluid of children with atopic dermatitis using skin chamber methods and evaluated the correlation with clinical symptoms. Skin chambers were applied to forearm skin which had been scratched with a needle, and an extract of Dermatophagoides farinae (mite antigen) at 50 μg/ml in saline was added through 0.3-μm filters as a challenge. We measured the concentrations of tryptase and histamine 2, 6, 12, and 24 h after challenge. The skin chamber test was done before and after hospitalization therapy or beach camp therapy. We also tested patients with atopic dermatitis of varying severity, asthmatic patients without dermatitis, and normal volunteers. The histamine levels dramatically increased 24 h after challenge with mite antigen in patients with severe atopic dermatitis, whereas this was not observed in patients with mild atopic dermatitis or asthma and in normal volunteers. The levels of histamine in the chambers 24 h after challenge decreased along with improvement of skin condition after various kinds of treatment and beach camp therapy. These results indicate that the skin chamber test will be a useful objective tool to evaluate the skin conditions of patients with atopic dermatitis. The increase of histamine level was not accompanied by an increase in tryptase level, suggesting the importance of basophil activation in this disease.