[An immunocytochemical study of alpha 1-antichymotrypsin in the senescent cerebral amyloid].

An immunocytochemical study of alpha 1-antichymotrypsin (alpha 1ACT) was performed in order to demonstrate its localization and the relationship between alpha 1ACT and senescent cerebral amyloid. We examined 5 brains with dementia of the Alzheimer type (SDAT), a peripheral nerves of familial amyloidotic polyneuropathy (variant transthyretin type, FAP) and dorsal root ganglions of a primary amyloidosis with peripheral neuropathy (AL type, PA). Avidin-biotin-peroxidase complex method and double immunoenzymatic staining method (peroxidase-antiperoxidase method combined with avidin-biotin-alkaline phosphatase complex method) were used. Anti-beta protein serum was used as the marker of cerebral amyloid. About 98% of senile plaques had alpha 1ACT like-immunoreactivity (alpha 1ACTI). All types of plaques showed the immunoreactivity: Core and peripheral of typical plaques, primitive plaques, core plaques and amorphous cerebral amyloid deposits. Although, a part of a senile plaque showed beta protein like-immunoreactivity alone and the other part had alpha 1ACT, many remainder part of a senile plaque had both immunoreactivity. Of the other pathological changes of SDAT, eosinophilic tangles and cerebrovascular amyloid were positive, in contrast, intracellular tangles, granulovacuolar degeneration and Hirano body were negative. The amyloid from FAP had weak alpha 1ACTI and diffusely stained. alpha 1ACTI was seen in the peripheral margin of the amyloid from PA. These results indicate that alpha 1ACT is closely associated with senile plaques formation.