Quantification of regulatory T cells in peripheral blood of patients with systemic lupus erythematosus

Regulatory T cells (Tregs) are supposed to stop immune responses in the course of immune activation. However, chronic activation of immune system in systemic lupus erythematosus (SLE) and many other autoreactive disorders are evidence of malfunction of this system. Therefore, it is plausible to quantify presence of these cells in different diseases. Forty-one patients with diagnosis of SLE were enrolled in this study. Patients were divided into two groups of patients with active and inactive disease based on the disease activity score. Flow cytometry analysis was used to determine the frequency of regulatory T cells in peripheral blood according to high expression of CD25 and intracellular Forkhead/winged-helix (Foxp3). Further 30 healthy individuals considered as control group. Significantly less CD4+CD25hi regulatory T cells were detected in active patients (P < 0.001) compared to healthy individuals. The percentage of CD4+CD25hi cells were inversely correlated with the SLEDAI disease score in patients with active disease (r = −0.837, P < 0.0001). Patients with active disease had lower frequencies of CD4+Foxp3+ cells. However, increased frequencies of CD4+Foxp3+ T cells were observed in peripheral blood of patients with inactive disease compared with active patients or healthy individuals (P < 0.010). Moreover, a significant difference between the proportion of CD4+CD25-Foxp3+ population in healthy controls and patients with active disease was shown (P < 0.0005). Presence of lower frequencies of Tregs in patients with SLE could be evaluated as an immune turbulence and could be employed as a target for immunotherapeutic manipulation. However, controversies need to be resolved.