Evaluation of interleukin-18 and soluble interleukin-2 receptor serum levels in patients with alopecia areata: an Egyptian study

Abstract

Background Alopecia areata (AA) is a chronic inflammatory disorder of hair follicle cycling characterized by nonscarring hair loss. Interleukin-18 (IL-18) is a proinflammatory cytokine that was implicated in various inflammatory and autoimmune skin diseases, including AA. IL-2 initiates and develops the immune response through binding to interleukin-2 receptor (IL-2R) on T cells. Levels of soluble IL-2R (sIL-2R) may be estimated as a sign of T-cell activation in serum of patients having many disorders involving aberrant immune activation, including AA. Objective To estimate of the serum levels of IL-18 and sIL-2R as immunological factors in patients with AA and to test the correlation between these serum levels and disease severity. Patients and methods A total of 46 patients with AA and 40 age-matched and sex-matched healthy individuals as controls were included. All participants were subjected to thorough history taking, full general examination, and detailed dermatological examination for diagnosis of cases and determination of extent of the lesions. The severity of AA was graded as mild (three or less patches of alopecia with a widest diameter of 3 cm or less or the disease limited to the eyelashes and eyebrows) or severe (existence of more than three patches of alopecia or a patch >3 cm at the widest diameter or alopecia totalis or alopecia universalis). Estimation of serum levels of IL-18 and sIL-2R was done by enzyme-linked immunosorbent assay. Results Serum IL-18 was significantly higher in patients with AA compared with the controls. Serum sIL-2R was nonsignificantly increased among patients with AA than the controls. Patients with severe disease had significantly higher serum IL-18 and nonsignificantly higher serum sIL-2R compared with patients with mild disease. Conclusion AA is associated with elevation of serum IL-18 and sIL-2R, and their levels increase with the increase in the severity of the disease. The exact role of serum IL-18 and sIL-2R in AA should be investigated in future studies.