CD4+CD25-Foxp3+T cells can be detected in urine samples of patients with active nephritis and correlate with the extent of proteinuria. (a) CD4+CD25-Foxp3+ T cells were analyzed by fluorescence-activated cell sorting (FACS) in blood and urine sediment samples from SLE patients with active nephritis. One representative dot plot is shown. (b) The percentage of CD4+CD25-Foxp3+ T cells was correlated with the extent of proteinuria (r = 0.4; P = 0.002). (c) One representative longitudinal analysis of the percentage of CD4+CD25-Foxp3+ T cells together with the extent of proteinuria is shown in a patient with newly diagnosed active glomerulonephritis treated with a monthly boli of cyclophosphamide. CYC, cyclophosphamide; MMF, mycofenolate mofetil.