The SJL/J mouse: a new model for spontaneous age-associated amyloidosis. I. Morphologic and immunochemical aspects.

A high incidence of spontaneous amyloidosis is described in SJL/J mice. Amyloid was detected as early as 30 weeks of age and the incidence rose to 90 per cent by 60 weeks of age. Amyloid deposits were most prominent in the perifollicular zones of the spleen and the lobular areas of the liver. Ultrastructural analysis revealed rigid, nonbranching fibrils indistinguishable from those observed in casein-induced murine amyloidosis. On the other hand, immunochemical studies indicated that amyloid deposits in SJL/J mice differ from those found in casein-treated CBA mice with respect to size, amino acid content, and antigenic properties. Since the SJL/J mouse also develops spontaneous reticulum cell tumors and serum M components, it appears to be a useful model for study of the pathogenesis of amyloidosis and its relationship to aging, neoplasia, and certain B-cell dyscrasias.