CD4+CD25high FoxP3 expression in the peripheral blood of patients with systemic lupus erythematosus and rheumatoid arthritis

Background A total of 1–2% of the regulatory T cells (Tregs) CD4+CD25+ express high levels of CD25 and are called CD4+ CD25high cells. The forkhead family transcription factor (FoxP3) has been described as a highly specific intracellular marker molecule for Tregs. A decrease in the number of CD4+CD25high FoxP3 Tregs could play a key role in the loss of tolerance to self-antigens. Objective To study the role of Tregs CD4+CD25high FoxP3 in the peripheral blood of patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) and correlate them with the activity of both diseases. Patients and methods The study was carried out on 15 SLE patients, 15 RA patients, and 15 healthy controls. SLE and RA patients were divided into two groups: group A had moderate activity and group B had mild activity according to the systemic lupus activity measure and the disease activity score of RA, respectively. All individuals were subjected to complete blood picture, erythrocyte sedimentation rate, serum creatinine, rheumatoid factor, complement 3, antinuclear antibodies, anti-dsDNA, and flow cytometric assay of CD4+CD25+, CD4+CD25high, and CD4+CD25high FoxP3 expression in patients and controls. Results A significant decrease was observed in the mean percentage of CD4+CD25high cells in the peripheral blood of patients with moderate activity SLE when compared with patients with mild activity and healthy controls and between patients with mild activity and controls (Po0.01 for each). The mean percentage of CD4+CD25high FoxP3 cells was significantly decreased in SLE patients with moderate activity when compared with those with mild activity and controls and between patients with mild activity and controls (Po0.001 for each). With regard to RA patients, the mean percentages of CD4+CD25high and CD4+CD25high FoxP3 cells in the peripheral blood did not differ in both groups of RA compared with normal controls. Conclusion Decreased expression of CD4+CD25high and CD4+CD25high FoxP3 may be related to the immunodysregulation of SLE. Thus, FoxP3 can be a potential therapeutic target for SLE. A further large-scale study on untreated active RA patients may be needed to clarify the role of Tregs in RA.