Page 1069 - Veterinary Immunology, 10th Edition

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FIG. 32.8 A classification of different forms of
membranoproliferative glomerulonephritis.

Type I Membranoproliferative Glomerulonephritis

Type I MPGN is caused by immune complex deposition in
glomerular vessels. These complexes usually penetrate the vascular
endothelium, but not the basement membrane, and are therefore

trapped on the inside, where they stimulate endothelial cell
swelling and proliferation (Fig. 32.9). If an animal is given repeated
injections of small doses of an antigen over a long period, continued
damage to the glomerular cells by immune complexes leads to

production of transforming growth factor-β (TGF-β). This cytokine
stimulates nearby cells to produce fibronectin, collagen, and
proteoglycans. This results in a thickening of the basement
membrane to form the so-called “wire loop” lesion (also called a

membranous glomerulonephritis). Alternatively, the immune
complexes may be deposited in the mesangial region of glomeruli.
Mesangial cells are modified smooth muscle cells. As such they can
release cytokines and prostaglandins and ingest immune
complexes. They respond to these immune complexes by

proliferation and production of IL-6 and TGF-β. The IL-6 stimulates

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