Microtubule-associated proteins tau and amyloid P component in Alzheimer's disease.

The localization of the intracerebral microtubule-associated proteins tau (MAP-tau) has been compared to that of amyloid P component (AP), an extracerebral protein, by single- and double-antigen immunohistochemistry in neurofibrillary tangles of Alzheimer's brains. The results show that, individually, MAP-tau and AP may be observed in all stages of neurofibrillary tangle (NFT) formation. However, NFT labeled by MAP-tau and those labeled by AP largely do not overlap in their distribution. Furthermore, within the few NFT double-labeled by MAP-tau and AP, there was an inverse relationship between the immunoreactivity to MAP-tau and to AP. It is suggested that MAP-tau and AP are incorporated at different times into NFT and that this difference in the timing of NFT expression of these 2 proteins may be useful in the study of progressive NFT formation.