Protease nexin I immunostaining in Alzheimer's disease.

Immunohistochemical experiments showed that a small subset of neuritic plaques in brains affected by Alzheimer's disease stain positively with an antibody to the protease inhibitor protease nexin I. Nearly all plaques and tangles throughout the brain also showed a heightened avidity for a protease nexin I antibody-antigen aggregate, suggesting that plaques and tangles may have a particularly high density of protease nexin I-binding sites. These observations provide further evidence for a potential disruption of protein processing in the brains of patients with Alzheimer's disease.