Tissue factor antigen in senile plaques of Alzheimer's disease.

Tissue factor (tissue thromboplastin) is the primary initiator of the extrinsic coagulation pathway, triggering a proteolytic cascade when exposed to circulating coagulation factors. In this study, the distribution of tissue factor was examined immunohistochemically in Alzheimer's disease (AD) and control brains. Tissue factor was expressed diffusely in the neocortex, but in AD there was enhanced immunoreactivity in senile plaques. Although tissue factor might potentially contribute to the formation of senile plaques, it could also accumulate in the plaques as a secondary response to other biochemical perturbations.