A comparative immunohistochemical study of kuru and senile plaques with a special reference to glial reactions at various stages of amyloid plaque formation

The authors examined 10 patients with Gerstmann-Straussler syndrome or Creutzfeldt-Jakob disease and 10 with Alzheimer's disease (AD). Immunohistochemistry using anti-prion protein (PrP) and anti-β/A4 protein (β/A4) coupled with formic acid pretreatment could detect Congophilic and non-Congophilic deposits. Prion protein deposits were classified into five types and compared with types of β/A4 deposits. Kuru plaques with multicentric cores and fine granular deposits were a characteristic feature of PrP deposits. Some types of PrP or β/A4 deposits depend on the anatomic sites. To clarify the relationship of microglia and astrocytes to PrP or β/A4 deposits, double-immunostaining method was performed. In both kuru and senile plaques, microglia were closely linked to the Congophilic plaques. Astrocytes, however, extended their processes toward the plaques even in the non-Congophilic plaques. These observations strongly suggest that similar glial association with plaque formation may be involved in both kuru and senile plaques, although the amyloid core proteins differ.