The role of the mesangial cell in proliferative glomerulonephritis.

In 40 patients with a histological diagnosis of proliferative glomerulonephritis the deposition of immunoglobulins, complement (C(3)), and fibrin/fibrinogen has been assessed by immunofluorescence and electron microscopy. The results of such examinations have been correlated with the outcome of the illness. In minor or resolving disease there is usually minor functional impairment, a good response to therapy or spontaneous resolution, the deposition of small amounts of material in glomerular capillary walls, and active mesangial removal. In moderate to marked disease there is initially a moderately severe functional disorder, a good response to therapy, considerable deposition of material in glomerular capillary walls but with less active mesangial regions than in the previous group. In progressive glomerulonephritis there was initial severe functional disorder, poor response to therapy, large amounts of material deposited within capillary walls, and active mesangial regions which were greatly enlarged, containing numerous deposits. In the rapidly progressive group there was severe functional disorder with poor response to therapy, the deposition of only small amounts of material within capillary walls, the lack of any significant mesangial cell reaction, and the formation of epithelial crescents. The results of the study indicate that in proliferative glomerulonephritis following the deposition of material in glomerular capillary loops, the progression of the disease is, to some extent at least, dependent upon the ability of the mesangial cell to remove such material.