IN VITRO AND IN VIVO MOUSE MODELS FOR AL AMYLOIDOSIS

摘要

AL amyloidosis is caused by an amyloidogenic immunoglobulin (Ig) light chain secreted by a clonal plasma cell. Mechanisms by which fibrils or their precursors damage tissues are poorly understood, and investigation of this would be facilitated by a reproducible, stable, genetically defined animal model. To develop such a model, we are testing in vitro and in vivo expression systems for light chains using a variety of vectors and cell lines. Vectors include viral and mammalian promoters for both ubiquitous and lymphoid specific expression and cell lines include COS cells, fibroblasts, and plasmacytoma cells. A full-length human lambda6 light chain cloned from a patient with aggressive multi-organ AL amyloidosis has been expressed transiently and stably. The CMV viral promoter confers high level expression in stably transfected SP2/0 Ig~(-/-), mouse plasmacytoma cell lines. The lambda light chain can be detected by Western blot analysis in the cells and secreted into tissue culture supernatants in vitro. These cell lines have been implanted into syngeneic and RAG", mice to form tumors intraperitoneally and subcutaneously; RAG", mice will not generate mouse anti-human light chain antibody responses. The tumors secrete the human lambda6 light chain in vivo and it is detected in the circulation by Western blot. Although the duration of these experiments is limited by tumor size, the effect of light chain production is under ongoing investigation. Strategies for longer term expression are being developed, and the optimal constructs will be used to generate transgenic mice.