Coexpression of a novel glomerular basement membrane matrix material in mesangial cell culture and glomerulosclerosis.

After in vivo administration of purified antibody against cultured mesangial cell (anti-MC IgG), glomerular basement membrane (GBM) was selectively bound. The glomerular bound anti-MC IgG exhibited a monospecificity for a 109-kDa antigen extracted from cultured mesangial cells and normal GBM. The antigen was not digestible by collagenase, heparitinase, or chondroitinase and was revealed by immunoelectron microscopy of a normal glomerular component to be predominantly distributed along the lamina rara externa of GBM and to be absent in mesangium. The ample expression of the antigen in puromycin aminonucleoside nephrosis implies that it represents a significant sclerotic material in glomerulonephritis. Abnormal production of GBM components by mesangial cells may play an important role in glomerulosclerosis.