IMMUNOHISTOCHEMICAL EVIDENCE FOR THE LACK OF AMYLOID-P COMPONENT IN SOME INTRA-CEREBRAL AMYLOIDS

Abstract

Sections of brain tissue from patients with Alzheimer''s disease with amyloid deposits in vessels, plaques and nerve cells were studied by an immunoperoxidase method using a specific antiamyloid P component (AP) antiserum. Amyloid deposits in vessels were strongly positive for protein AP, whereas the Alzheimer''s plaques and the neurofibrillary tangles were negative or only weakly positive. The absence of protein AP in some intracerebral amyloid deposits might be due to an inability of the protein to penetrate the blood-brain barrier. Protein AP is absorbed to already formed amyloid fibrils, but it may participate in the formation of vascular amyloid. Protein AP is not necessary for the formation of amyloid fibrils, at least in some forms of cerebral amyloidosis.