Integrins are a family of adhesion molecules which mediate adhesion and interaction between cells and extracellular matrix. The renal glomerulus is composed of cellular components and extracellular matrix. To clarify the role of integrins in the progression of glomerulonephritis, we examined the expression of β1 integrin and fibronectin, which is a ligand of β1 integrin, in the glomeruli in patients with IgA nephropathy and membranous nephropathy by an indirect immunofluorescence study and immunoelectron microscopic study using specific antibodies. β1 integrin was expressed on the surface of mesangial cells, glomerular epithelial cells, endothelial cells and Bowman's capsullar epithelial cells in normal control glomeruli. The expression of β1 integrin and fibronectin was increased in the mesangial area in patients with IgA nephropathy showing mesangial proliferation and mesangial matrix increase. β1 integrin may play an important role in the construction of the glomerulus and also in the deposition of immunecomplex, proliferation of mesangial cells, and increase in extracellular matrix in IgA nephropathy.
