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 glomeru
lonephritis [1-4]. However, most of these markers are more closely ass
ociated with renal tubulointerstitial injury than glomerular injury. I
t has been demonstrated that mononuclear cells (macrophages and lympho
cytes) are involved in the pathogenesis of various types of human glom
erulonephritis, as well as in animal models [5-7]. If mononuclear cell
s are involved in glomerular injury, it can be assumed that such cells
could be detected in urine; however, to our knowledge, the characteri
zation of mononuclear cells in urine has not been investigated. We hav
e recently demonstrated that increased numbers of mononuclear cells ar
e observed in the urine of patients with active IgA nephropathy and th
at 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 us
efulness of analyzing mononuclear cells in urine as a non-invasive dia
gnostic tool for glomerular injury.