ISSN:
1432-2307
Keywords:
Key words Amyloid
;
λ Light chain
;
Osseous metaplasia
;
Plasmacytoma
;
Protease
;
Tonsil
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract We report of a 58-year-old Caucasian man who was referred to the University Hospital with a greatly enlarged left tonsil which showed calcifications on computed-tomography scans. Histopathology revealed a plasmacytoma with secondary AL amyloidosis, ossifications, and multinucleated foreign-body-type giant cells. N-terminal sequencing of amyloid-fibril proteins purified from the formalin-fixed tissue showed the presence of two proteins of different size; these were of λ-light-chain origin (subgroup V), measured approximately 15.2 kDa and 10.5 kDa, and had identical N-terminal ends (YVLTQPP). When the amyloid deposits were immunolabeled with a polyclonal antibody directed against λ light chain, they showed two staining patterns: some deposits showed intense immunolabeling while others were not immunoreactive. Immunostaining of amyloid was completely absent after protease pre-treatment. Immunoelectron microscopy with gold-labeled secondary antibodies showed staining that was spatially related to amyloid fibrils and suggested that the antibody probably detected the fibril protein. Therefore, our hypothesis in this case is that the different immunostaining patterns are due to a post-fibrillogenic proteolysis of the fibril protein at the C-terminal end of the light chain, as indicated by the presence of two differently sized λ-light-chain fragments with identical N-terminal ends.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004280050456
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