Localization of Alzheimer amyloid beta protein precursor and its relation to senile plaque amyloid

The authors examined the ultrastructural localization of amyloid beta protein precursor (APP) in normal human brains immunohistochemically using 3 kinds of APP antisera. The patterns of immunoreaction differed between the antisera used. Antiserum 770, against APP1-770, predominantly labeled the cytoplasm of neurons, whereas antiserum Z31, against the pre-beta region of the APP, labeled astroglial processes intensely and neurons to a lesser extent. Antiserum 1736, against the N terminal of beta protein, labeled both neurons and astrocytes. Vascular smooth muscle cells and some of the endothelial cells in the cerebral arterioles and capillaries were labeled with Z31 and 1736. The APP exists in every cells, while various patterns of immunoreactivity may reflect the difference in the metabolic pathway of APP between cell types.