Serum Interleukin-2 Level Associated with Treg/Th17 Ratio in Active Systemic Lupus Erythematosus

Introduction: Systemic lupus erythematosus (SLE) is resulted from loss of immunological tolerance. Interleukin-2 (IL-2) plays an important role in loss of tolerance in SLE through its influence on Treg and Th17 balance. This study was conducted to determine the correlation between serum IL-2 level with Treg/Th17 ratio in active SLE. Methods: This cross-sectional analytic study included thirty newly diagnosed SLE patients. IL-2 level was measured using ELISA, whereas Treg and Th17 expressions were measured using the flow cytometry method, then the ratio was calculated. The Systemic Lupus Activity Measure (SLAM) scores were used to assessed SLE disease activity. Results: All patients were female with mean age of 31±10 years. Hematological conditions and arthritis were the most prominent clinical manifestations. All patients were in active SLE conditions with a high mean SLAM score of 29±4. Serum IL-2 level was lower in SLE patients compared to healthy subjects (median 7.12 pg/mL vs 49.31 pg/mL, respectively). Treg/Th17 ratio was also lower in SLE patients compared to healthy subjects (median 0.405 vs 0.830, respectively). There was a significant correlation between serum IL-2 level with Treg/Th17 ratio (r = 0.463; P = 0.01). Conclusion: Serum IL-2 level is associated with Treg/Th17 ratio in active SLE.