The Diagnostic Role of Membrane-Bound CD27 in Non-Segmental Vitiligo: A Case–Control Study

Background: This study included 120 participants (60 patients with non-segmental vitiligo and 60 healthy controls). Previous positive evidence in vitiligo concerns serum soluble CD27 (sCD27), whereas flow cytometry directly quantifies membrane-bound CD27 on circulating lymphocytes.Objectives: The study aimed to determine whether the percentage of CD27-positive events within gated peripheral-blood lymphocytes can discriminate patients from controls, and to compare expression by treatment status and available demographic characteristics.Materials and Methods: A hospital-based case–control study was conducted from September 2025 to February 2026 at two dermatology clinics in Najaf, Iraq. Eligible clinic attendees and healthy volunteers were enrolled by non-probability convenience sampling until the prespecified groups were filled. The patient group comprised 30 on-treatment and 30 treatment-naïve participants. Peripheral-blood mononuclear cells were stained with anti-human CD27-PE and anti-CD45 PerCP-Cy5.5, and at least 30,000 events were acquired within the lymphocyte gate on a BD FACSCanto II flow cytometer.Results: Membrane-bound CD27-positive lymphocyte percentages did not differ among controls (55.84 ± 14.62%), on-treatment patients (56.90 ± 14.85%), and treatment-naïve patients (57.98 ± 14.78%; F(2,117) = 0.218; exact P = 0.803). The on-treatment and treatment-naïve subgroups also did not differ (Welch t(58.00) =-0.282; exact P = 0.779). Receiver-operating-characteristic analysis yielded an area under the curve (AUC) of 0.531 (95% CI 0.428–0.635); this value is close to chance discrimination, and the optimal cut-off of 51.47% provided 73.3% sensitivity but only 40.0% specificity.Conclusion: Membrane-bound CD27 was not shown to be a suitable standalone diagnostic biomarker in the present study. These findings suggest that membrane-bound CD27 should not be used alone as a diagnostic biomarker for vitiligo in routine clinical practice.