CD3+CD4+T cell leucopenia in systemic lupus erythematosus (SLE) patients. (a) Percentage of CD4+ T cells in the peripheral blood mononuclear cells (PBMCs) of patients and healthy controls (HCs). CD4+ T cell percentages was also compared between untreated patients (none, N = 28) and patients treated with either steroids alone (ST, N = 15) or immunosuppressive drugs alone (IS, N = 53) or both (IS + ST, N = 32). Each patient group was compared to HCs using Dunns' multiple comparison tests. (b) Percentage of CD4+ T cells in the PBMCs of SLE patients according to their disease activity (non-active, active non-renal and active renal). (c) Representative PBMC fluorescence activated cell sorter (FACS) plots showing the CD45RO - CD45RA and CD45RO - CD62L stainings gated on CD3+ CD4+ lymphocytes. (d) Representative FACS plots showing FOXP3 and CD25 staining gated on CD4+ lymphocytes of two PBMC samples three days after stimulation with anti-CD3 and anti-CD28. (e) Freshly obtained blood was stained with a combination of antibodies to CD3, CD4, CD25, and CD127. Following red blood cell lysis, the cells were permeabilized and stained for FOXP3 expression. The FACS plot shows a representative profile gated on CD3+ CD4+ lymphocytes, with the regulatory T cells (Tregs) being identified as FOXP3+ CD127-. (f) Percentage of circulating Tregs identified as shown in (e) in HCs and SLE patients partitioned by disease activity.