Spontaneous amyloidosis in LLC mice.

Practically all low leukocyte count (LLC) mice over 1 year of age develop renal amyloidosis. Renal amyloid is deposited in the glomeruli and in the interstitium between the convoluted as well as collecting tubules, with consequent development of cysts and necrosis. LLC mice die of chronic renal failure. Electron microscopic studies reveal amyloid fibrils in the mesangium, a thickening of the basement membranes, and fusion of the foot processes in the glomeruli. Massive amounts of amyloid fibrils are also present in the interstitium, where intracellular fibrils in the fibroblasts as well as in the tubular epithelium cells are found. Vesicles, which are probably formed from membrane disruption, and amorphous materials are seen along the basement membranes. LLC mouse amyloidosis is discussed with regard to its potential as a model for studies on amyloidosis as well as the etiology and origin of amyloid fibrils.