Exploring the missing links: the correlations between interleukins 15 and 38 with vitiligo activity and severity

Background Vitiligo is an immune-mediated depigmenting disorder characterized by melanocyte destruction driven by dysregulated cellular immunity. Interleukin-15 (IL-15) promotes survival of cytotoxic memory T cells implicated in vitiligo persistence, whereas IL-38 is a regulatory cytokine with potential anti-inflammatory effects. However, their roles in vitiligo severity and activity remain incompletely defined. Objectives To compare serum IL-15 and IL-38 levels in vitiligo cases and healthy controls and to evaluate their associations with disease severity and activity. Patients and methods A total 40 nonsegmental vitiligo sufferers and forty healthy controls were enrolled. Severity and activity of vitiligo were assessed using Vitiligo area severity index (VASI) and vitiligo disease activity scores. The level of IL-15 and IL-38 in blood was measured using ELISA. Results Vitiligo patients exhibited significantly higher serum IL-15 levels compared with controls (median: 49.47 vs. 11.05 pg/ml, P <0.001), while serum IL-38 levels were significantly lower (median: 11.05 vs. 44.45 pg/ml, P <0.001). Serum IL-15 levels showed a significant positive correlation with VASI scores (rs=0.506, P =0.001), whereas IL-38 levels demonstrated a strong negative correlation with VASI scores (rs=−0.998, P <0.001). A significant inverse correlation was also observed between IL-15 and IL-38 levels (rs=−0.503, P =0.001). Neither cytokine correlated significantly with age, disease duration, or vitiligo disease activity score. Conclusion The imbalance between IL-15 and IL-38 reflects a dysregulated immune milieu in vitiligo, suggesting that these cytokines may contribute to disease pathogenesis and severity.