Alzheimer dementia and Pick's disease: neurofibrillary tangles and Pick bodies are associated with identical phosphorylated neurofilament epitopes.

Sections of formaldehyde-fixed paraffin-embedded cortical and hippocampal brain tissue from five cases with senile dementia of Alzheimer type (SDAT) and five cases with Pick's disease (PD) were immunostained with the monoclonal antibodies (mabs) 147, RT 97, BF 10 and 8D8 with and without pretreatment with alkaline phosphatase (AP) or trypsin (Tr). The mabs 147, RT 97 and BF 10 had previously been demonstrated to bind exclusively to phosphorylated epitopes of neurofilament proteins, while mab 8D8 is shown in this report to bind mainly, but not exclusively, to phosphorylated neurofilament epitopes. The mabs RT 97, BF 10 and 8D8, but not 147 stain most, if not all, Pick bodies (PB) and Alzheimer neurofibrillary tangles (NFT). When sections are pretreated with AP or Tr the immunostaining with mab BF 10 is very resistent in both PB and NFT. This resistance of PB and NFT is in contrast to the reduced staining of axons and of swollen cells in PD by the same enzymatic pretreatment. Immunostaining with mab RT 97 of PB and NFT is reduced moderately by AP and considerably by Tr. Only when stained with mab 8D8 is there a discrepancy between PB and NFT in their reaction to the pretreatment with AP: NFT staining with mab 8D8 is not affected, while that of PB is abolished. Thus, in spite of their different ultrastructure, PB and NFT are very similar immunocytochemically and in the accessibility of their phosphorylated epitopes to enzymatic treatment.