A comparative study of histological and immunohistochemical methods for neurofibrillary tangles and senile plaques in Alzheimer's disease.

Several studies have demonstrated that the accurate visualization and quantification of pathological lesions in neurodegenerative disorders depend on the reliability of staining methods. In an attempt to gain a better assessment of the density and distribution of the neuropathological markers of Alzheimer's disease, we compared the staining efficiency of a modified thioflavine S protocol for neurofibrillary tangles (NFT) and senile plaques (SP) to different argentic impregnation techniques (Bielchowsky, Gallyas, Globus, Campbell-Switzer-Martin) and to immunohistochemical stainings obtained with two different antibodies against the amyloid beta protein A4 and the microtubule-associated tau protein. The modified thioflavine S technique (MTST) detects up to 60% more SP and up to 50% more NFT than the Bielschowsky and Globus methods, respectively. The results obtained with the specific antibodies are comparable to those obtained with the MTST, but these immunotechniques are more expensive and time consuming for routine neuropathological evaluation, and the appropriate antibodies are not always commercially available. Furthermore, the morphological appearance of NFT and SP with MTST is greatly improved when compared to the classical thioflavine S and the increased signal-to-noise ratio between specifically stained structures and background permits an accurate semi-automatic quantification.