Serum level of IL‐4 predicts response to topical immunotherapy with diphenylcyclopropenone in alopecia areata

Background This study investigated predictors of response to topical diphenylyclopropenone (DPCP) immunotherapy in patients with alopecia areata (AA). Objective To identify predictors of response, or resistance, to treatment for AA through clinical observations and serum tests. Methods Eighty four AA patients were treated with DPCP. Serum cytokine levels were measured in 33 AA patients pre‐ and post‐treatment, and in 18 healthy controls, using ELISA assays. Results Of patients, 56.1% responded to DPCP with satisfactory hair regrowth; the response rate was negatively correlated with hair loss extent. Before DPCP treatment, higher serum IFN‐γ and IL‐12 cytokine levels were observed in AA patients compared to healthy controls. Non‐responders to DPCP had significantly elevated serum IL‐4 pre‐treatment (3.07 fold higher) and lower IL‐12 levels compared with responders. After DPCP treatment, non‐responders had persistently high IL‐4, increased IL‐12, negligible decrease in IFN‐γ and decreased IL‐10. Post‐treatment DPCP responders exhibited significantly decreased IFN‐γ and IL‐12, and increased IL‐4 and IL‐10. Development of adverse side‐effects was significantly associated with higher pre‐treatment serum IgE levels. Limitations A small number of subjects were evaluated. Conclusions Potentially, elevated pre‐treatment serum levels of IL‐4 and IL‐12 can be used as unfavorable and favorable predictors of DPCP therapeutic effect, respectively. In addition, pre‐treatment elevated serum total IgE may predict increased risk for severe adverse side‐effects to DPCP application. Whether serum cytokine expression levels can be used as predictors of response to other forms of treatment is unknown, but it may warrant investigation in the development of personalized treatments for AA.