Analysis of mononuclear cells in urine using flow cytometry in glomerular diseases

Analysis of urinary substances, such as low molecular weight proteins and enzymes localized in the proximal tubulus and cytokines, has been proposed as being useful in monitoring the disease activity of glomerulonephritis [1-4]. However, most of these markers are more closely associated with renal tubulointerstitial injury than glomerular injury. It has been demonstrated that mononuclear cells (macrophages and lymphocytes) are involved in the pathogenesis of various types of human glomerulonephritis, as well as in animal models [5-7]. If mononuclear cells are involved in glomerular injury, it can be assumed that such cells could be detected in urine; however, to our knowledge, the characterization of mononuclear cells in urine has not been investigated. We have recently demonstrated that increased numbers of mononuclear cells are observed in the urine of patients with active IgA nephropathy and that the extent of active crescents in biopsy specimens is significantly correlated with the number of urinary macrophages and natural killer cells [8]. The aim of the present study is to evaluate the clinical usefulness of analyzing mononuclear cells in urine as a non-invasive diagnostic tool for glomerular injury.