LOSS OF CONTACT SENSITIZATION EVALUATED BY LASER-DOPPLER BLOOD FLOWMETRY AND TRANSEPIDERMAL WATER-LOSS MEASUREMENT

Allergic contact dermatitis, which is mediated by activated T cells th rough a Type IV reaction, is usually believed to persist throughout li fe. There have been several reports of spontaneous loss of sensitizati on, e.g., loss of previous patch test reaction or loss of allergic con tact dermatitis withal continuous exposure to the allergens. However, these have not been well quantified. The aim of this study was to conf irm the development of desensitization or hyposensitization with the a id of objective measurements. A total of 18 patients with alopecia are ata, who had received 4 months diphenylcyclopropenone (DPCP) contact i mmunotherapy, were patch tested and the responses were measured by las er Doppler blood flowmetry (LDF) and transepidermal water loss (TEWL). Patch tests were performed 2x, before and after 4 months of immunothe rapy. To determine whether local desensitization developed, we compare d change of DPCP concentrations producing mild contact dermatitis on t he scalp. Our results showed that systemic and local hyposensitization occurred in human subjects by weekly applications of low concentratio ns of DPCP for 4 months. LDF seems to be more correlated with visual s cores than TEWL measurement.