Morphometric comparison of the quantity of the mesangial deposits in rebiopsied patients with idiopathic mesangial proliferative glomerulonephritis

We examined 17 patients with idiopathic mesangial proliferative glomerulonephritis (MPG) who had undergone repeated renal biopsies and for whom both light and electron microscopy as well as immunofluorescence microscopy and full clinical data were available. Ultrastructural investigations were carried out by a computer image analysis system to compare quantitatively the area of the mesangial deposits in serially biopsied patients with MPG, and to find out whether this parameter would correlate with the degree of proteinuria. Another purpose of this study was to verify whether the intensity of the glomerular infiltrates of monocytes/macrophages depends on the accumulation of mesangial deposits. Comparisons between the first biopsy and rebiopsy showed that the mean values of the deposit area per mesangial area were significantly decreased at rebiopsy. Similarly, the glomerular infiltrates of monocytes/macrophages were significantly greater at the first biopsy than they were at rebiopsy. At the first biopsy and at rebiopsy, a significant, positive correlation existed between the density of the mesangial deposits and glomerular monocytes/macrophages as well as proteinuria. Glomerular infiltrates of monocytes/macrophages correlated positively with proteinuria in both the first biopsy and rebiopsy groups. In conclusion, this study points out that the density of the mesangial deposits and glomerular infiltrates of monocytes/macrophages were significantly decreased at rebiopsy, as compared with the first biopsy. Cited data and results of the correlative study correspond with the observation that in most of our serially biopsied patients, proteinuria at rebiopsy was significantly lower than that at the initial biopsy, a finding that might explain the clinical improvement in these cases.