ABSTRACT
BACKGROUND/OBJECTIVE: A search for the ideal biomarker for lupus nephritis (LN) is still underway, one that can be used for early detection and correlate with the class and activity of LN. Urine is normally devoid of leukocytes; however, it has been observed that macrophages and T lymphocytes are routinely present in the urine of LN patients and those with other proliferative renal diseases. This provides the idea for their potential use as biomarkers for proliferative LN. Here, we measured the urinary CD4+, CD8+ T lymphocytes, and CD14+ monocytes in patients with systemic lupus erythematosus (SLE) as potential biomarkers for LN. METHODS: A longitudinal case-control study included 30 SLE patients with LN, 30 SLE patients without past or current LN, and 20 healthy subjects as a control group. The flow cytometric analysis was done using BD FACS Calibur multiparameter flow cytometer equipped with BD CellQuest Pro software for data analysis. RESULTS: CD14+ cells were the most abundant cells in the urine of LN patients. The mean numbers of urinary CD8+, CD4+, and CD14+ cells/mL were significantly higher in patients with LN than in those without. The cell counts correlated significantly with proteinuria. Urinary CD14+ cells seem to occur in much higher counts in class IV than class III LN. CONCLUSIONS: Urinary CD8+, CD4+, and CD14+ cells are highly sensitive and specific markers for detecting proliferative LN. A low CD4:CD8 ratio provides a further clue. Urinary CD14 cell counts may be a potential biomarker to differentiate between the different classes of proliferative LN.