A quantitative study of mesangial deposits and glomerular monocytes/macrophages in IgA-nephropathy and proliferative mesangial (non-IgA) glomerulonephritis.

Twelve renal biopsy specimens from patients with idiopathic diffuse IgA nephropathy (IgAN) and 13 from patients with primary proliferative mesangial non IgA glomerulonephritis (PMGN) for whom both light and electron microscopy as well as immunofluorescence microscopy and full clinical data were available were examined and quantitatively compared. Morphometric investigations performed by means of a computer image analysis system were undertaken to compare the deposit area per mesangial area in IgAN and PMGN, as well as to study whether this parameter could correlate with the intensity of the glomerular infiltrates of monocytes/macrophages and with hematuria. The results showed that the mean values of the deposit area per mesangial area were significantly increased in IgAN patients in comparison with PMGN group. There were strong positive correlations between the area of the mesangial deposits and the mean number of the glomerular CD 68 positive cells in both IgAN and PMGN groups. Correlations between the area of the mesangial deposits and hematuria were also positive, but only in IgAN patients this relationship reached statistical significance. In conclusion, the present study pointed out that the deposit area per mesangial area was significantly increased in IgAN if compared with PMGN. Moreover, the results suggest that lack of fast catabolism of the mesangial deposits in IgAN may depend on the small number of monocytes/macrophages in the glomeruli. Positive correlations between deposit area per mesangial area and hematuria are not clear and need further investigations.