Immunohistochemical study of Alzheimer's disease using antibodies to synthetic amyloid and fibronectin.

Etiology and source of amyloid deposition in senile plaques of Alzheimer's disease (AD) are still unknown. In order to know whether or not fibronectin (Fn), an adhesive glycoprotein, is related to the amyloid deposition in the senile plaque, we conducted immunohistochemical studies using polyclonal anti-Fn and affinity-purified anti-amyloid component (Affi 28). Affi 28 was made by immunizing a rabbit against the synthetic peptide corresponding to residues 1-28 of the amyloid core protein reported by Masters et al. (1985). According to this study, four points became clear. First, Affi 28 is able to stain the subpial regions of AD as well as cerebrovascular amyloid and amyloid plaque cores. Second, it is suggested either that the etiology and source of neurofibrillary tangles and Pick body is distinct from that of the senile plaque or that any Affi 28 determinants of neurofibrillary tangles and Pick body are obscured sterically. Third, Affi 28 is useful to distinguish the senile plaque from the amyloid plaque of Creutzfeldt-Jakob disease. Last, there is no association between the amyloid in the senile plaque and Fn, at least immunohistochemically. The absence of Fn in the senile plaque suggests that Fn may not be requested for the deposition of amyloid fibrils.