Serum interleukin 15 level may serve as a new marker for alopecia areata

Abstract

Background Alopecia areata (AA) is an autoimmune form of nonscarring hair loss that may affect any hair-bearing area. It is one of the most common forms of hair loss seen by dermatologists. The serum level of interleukin 15 (IL-15) is elevated in AA; subsequently, IL-15 limits the suppressive effect of regulatory T cells and activates CD8 + NKG2D + T cells to attack the cells of the hair bulb and initiate AA. Inhibiting IL-15 activity might be a breaking new therapeutic strategy in the treatment of AA. Patients and methods Serum IL-15 levels were measured by an enzyme-linked immunosorbent assay for 30 patients with active AA (group A), 30 patients with stable AA (group B), and 60 healthy participants of age-matched and sex-matched controls (group C). Results Serum levels of IL-15 were significantly increased in patients with AA and showed a significant positive correlation with severity (Severity of Alopecia Tool score) and activity of the disease. Receiver operating characteristics curve detected the validity of serum IL-15 in differentiating patients with AA from controls. The best cutoff point for IL-15 was determined to be more than or equal to 7.66 pg/ml, which was able to predict AA with 98.3 sensitivity and 100% specificity. Receiver operating characteristics curve of IL-15 was also conducted to evaluate the sensitivity and specificity of serum IL-15 as a diagnostic index for discrimination between active and stable AA cases, and the best cutoff point for IL-15 was determined to be more than or equal to 21.2 pg/ml, which was able to predict active AA, with 93.3 sensitivity and 100% specificity. Higher IL-15 levels were associated with prediction of severity and activity of AA. Conclusion Serum IL-15 may represent a new marker for AA diagnosis as well as a predictor of the disease severity and activity.