Analysis of CD14+ cells and CD56+ cells in urine using flow cytometry: a useful tool for monitoring disease activity of IgA nephropathy.

The interrelationship between glomerular inflammatory activity and urinary leukocytes was investigated in IgA nephropathy (IgAN). The numbers of T cells, macrophages, and natural killer (NK) cells in urine were evaluated using flow cytometry. The glomerular changes were studied by routine histopathological methods and by immunohistochemical methods using monoclonal antibodies. Biopsies were classified into three categories: non-crescentic IgAN (n = 44), inactive-crescentic IgAN (n = 17), and active-crescentic IgAN (n = 18). Macrophages (Leu M3/CD14) and NK cells (Leu 19/CD56) were predominantly present within active crescents, whereas T cells (Leu 4/CD3) were less frequently observed. A significant increase of mononuclear cells in urine was observed in patients with active-crescentic IgAN as compared with other groups. Moreover, the extent of active crescents in biopsies was significantly correlated with the number of CD14+ cells and CD56+ cells in urine (CD14: r = 0.6858, p < 0.01; CD56: r = 0.6373, p < 0.01). These findings suggest that analysis of CD14+ cells and CD56+ cells in urine using flow cytometry can be a useful tool for monitoring disease activity of IgAN.