Detection of Serum Levels of Interleukins-17, 21, 6 and Tumor Necrosis Factor-α in Patients with Patchy Alopecia Areata and Their Association with Disease Severity

Background/Objectives: Alopecia areata (AA) is a common autoimmune disorder characterized by non-scarring hair loss. The destruction of hair follicle cells is mediated by cytotoxic T cells, which release cytokines that contribute to tissue damage. Among these, Th17 cells produce key inflammatory mediators, including IL-17, IL-21, IL-6, and TNF-α, which may play a role in disease progression. This study aimed to evaluate the serum levels of IL-17A, IL-21, IL-6, and TNF-α in patients with patchy AA compared with healthy controls and to assess their association with disease severity. Methods: A cross-sectional analytical study was conducted on 50 patients with patchy AA and 50 age- and gender-matched healthy controls. Blood samples were collected, and serum cytokine levels were measured using enzyme-linked immunosorbent assay (ELISA) kits. Results: Of the patients, 70% were female (35 patients) and 30% were male (15 patients). Disease severity distribution showed that 66% had mild AA, 22% had moderate AA, and 12% had severe AA. Compared with controls, AA patients exhibited significantly elevated serum levels of IL-6, TNF-α, IL-17A, and IL-21 (p < 0.001). Additionally, cytokine levels showed a positive correlation with both age and disease duration, suggesting their potential role in disease progression. Conclusions: These findings highlight the involvement of pro-inflammatory cytokines in the pathogenesis of patchy AA and their correlation with disease severity. Understanding these cytokine interactions may provide insights into targeted therapeutic strategies in managing AA.