Haematoxylin/
Eosin staining was performed to screen for Hirano bodies from the temporal lobe including the hippocampus in 10
Pick's disease cases containing Pick bodies. Although the inclusions were confirmed in 9 out of 10 cases, only 4 out of 10 were particularly enriched with the eosinophilic bodies. These were subjected to immunostaining with
anticomplement antibodies and astrocyte marker antiglial fibrillary acidic
protein antibody and the HLA class II CR3/43 antibody to visualize microglia. An intraneuronal Hirano body was observed in one case that otherwise contained mainly the extracellular inclusions. In all cases, the extracellular Hirano bodies were seen lying adjacent to
soma of neurons within CA1 region of the hippocampus. The extracellular Hirano bodies stained intensely with C1q, the first component of the classical pathway of activation but remained unreactive against
antibodies to C4 and the C3 activation products (C3b and
iC3b) and the alternative complement pathway component
factor B. Hirano bodies also remained negative with the antiglial fibrillary acidic
protein for astrocytes and HLA class II antibody CR3/43 for microglia. The results demonstrate that Hirano bodies have strong immunoreactivity to C1q; however, whether other
complement components are associated with these inclusions remains to be further investigated.