Impaired responses of peripheral blood mononuclear cells to T-cell stimulants in alopecia areata patients with a poor response to topical immunotherapy

Background Topical immunotherapy with a contact allergen is effective in alopecia areata (AA). However, the mechanism of the effect is still unknown, and pretreatment prediction of the outcome of therapy in each patient remains difficult. Objectives To predict the clinical effect of this therapy in AA patients, we investigated the relationship between clinical responses to topical immunotherapy and in vitro proliferative responses of peripheral blood mononuclear cells (PBMC) to T-cell stimulants. Methods PBMC were taken from 67 AA patients before or during diphenylcyclopropenone immunotherapy and from 14 healthy controls, and proliferative responses to phytohaemagglutinin and staphylococcal enterotoxin B were evaluated by measuring [H-3]-thymidine incorporation. Results PBMC from the AA patients with a good clinical response to immunotherapy showed a normal level of proliferation, whereas PBMC from the poor responders showed a markedly suppressed proliferative response and interleukin (IL)-2 production, but increased IL-4 production compared with the controls. Conclusions The proliferative response of PBMC to T-cell stimulants may be one of the indicators of the clinical effect of topical immunotherapy for AA.