CD39 Expression in Peripheral CD4+ T Lymphocytes is Associated with Disease Activity in Patients with Systemic Lupus Erythematosus

Objective: CD39 is crucial for the function of lymphocyte subsets, including CD4-positive T cells and Tregs. This study aimed to investigate the relationship between the quantities of Tregs, CD4-positive T cells, and CD39 expression on these cells with SLE disease activity. Methods: Peripheral blood from 108 SLE patients was analyzed. Patients were divided into SLE active and remission groups based on disease activity. The percentages and absolute counts of CD4-positive T cells and Tregs, along with CD39 expression, were measured by flow cytometry. Correlations between these markers and disease activity were evaluated, and the potential of CD39 as a biomarker was assessed. Results: The SLE active group had higher percentages and numbers of CD4-positive T cells compared to the remission group, while Treg levels were lower. CD39 expression was significantly higher in both Tregs and CD4-positive T cells in the active group. CD39 expression on Tregs correlated positively with their percentage and number, while CD39 expression on CD4-positive T cells showed a negative correlation with their percentage and number. ROC analysis indicated that CD39 could be a useful biomarker for SLE disease activity. Conclusion: CD39 on CD4-positive T cells exhibits immune suppressive functions similar to Tregs. CD4+CD39+ T cells represent a subset with immunosuppressive capabilities, potentially serving as a more effective marker for distinguishing SLE disease activity.