Immunohistological study on the distribution of alpha 1-antichymotrypsin in Alzheimer's brain, compared to beta-amyloid precursor protein and beta-amyloid protein.

Distribution of alpha 1-antichymotrypsin was immunohistologically examined in Alzheimer's brains and compared with those of beta-amyloid precursor protein and beta-amyloid protein. Immunoblotting study revealed that alpha 1-antichymotrypsin existed in senile plaques extracted from Alzheimer's brain. Immunohistologically, rabbit polyclonal antiserum to alpha 1-antichymotrypsin reacted not only with well-defined amyloid deposits such as typical, primitive, core plaques and cerebrovascular amyloid, but also with so-called preamyloid deposits including large amorphous materials (diffuse plaques), subpial amorphous materials and granular deposits. The staining pattern of alpha 1-antichymotrypsin was almost the same as those of beta-amyloid precursor protein and beta-amyloid protein. The present study indicated that alpha 1-antichymotrypsin could play an important role in the formation of various kinds of amyloid deposits including preamyloid ones in Alzheimer's brain.