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The distribution of apolipoprotein E (ApoE) was studied in the brain tissue of cases of the amyotrophic lateral sclerosis-parkinsonism-dementia complex of Guam, locally known as lytico bodig disease (LB), and compared with cases of Alzheimer's disease (AD) and normal brain tissue. In both LB and AD, strong ApoE immunostaining was observed in association with pathological lesions. In LB, these were mainly extracellular neurofibrillary tangles (eNFTs) which were intensely immuno-positive for ApoE. Occasional diffuse beta-amyloid protein (beta AP) deposits appear in this disorder and they were moderately immunopositive. In AD, senile plaques and diffuse beta AP deposits were intensely immunopositive, while eNFTs were only moderately immunopositive. The reason for the strong association of ApoE with the pathological entities in LB and AD is unknown, but may be related to a scavenger function which does not involve lipid metabolism. In both LB and AD, subpial and layer I diffuse deposits were ApoE negative but beta AP positive. Intracellular NFTs were mostly ApoE negative. A few showed weak positive staining. These data suggest that ApoE appears in LB and AD pathological lesions only after they are well established. In all controls, as well as all LB and AD cases, strong ApoE immunoreactivity was observed in unidentifiable structures in capillaries. Weak staining in a few neurons and very weak staining of an occasional astrocyte was observed. The source of ApoE which is deposited on extracellular pathological structures in LB and AD is unknown.

Histological and immunohistochemical findings in 20 cases of frontotemporal dementias-8 cases of dementia of frontal lobe type (DFT), 7 cases of Pick's disease (PD), and 5 cases of motor neuron disease with dementia (MND/D)-are presented. Common features of all three syndromes were: frontotemporal atrophy, involvement of subcortical nuclei, and swollen chromatolytic cells. Ubiquitin (Ub)-positive and tau-negative inclusions in cortical, hippocampal, and motor neurons were found in MND/D and DFT cases, suggesting a common pathogenesis of MND/D and DFT. MND/D showed the same cytoskeletal alterations in motor nuclei as MND without dementia: Bunina bodies and skein-like, Ub-positive inclusions. DFT differed from PD in the preponderance of histopathological changes in upper cortical layers, the sparseness of chromatolytic cells, and the absence of tau-positive Pick bodies (PBs). There were, however, two transitional cases showing Pick-type histology but no PBs, thus linking DFT and PD. PBs expressed chromogranin B and secretoneurin strongly, but chromogranin A only weakly. They were negative for the 70-kDa heat-shock protein, metallothionein, and glutathione-S-transferase.

Alzheimer's disease (AD) is characterised neuropathologically by the presence of abundant extracellular beta-amyloid deposits and intracellular neurofibrillary lesions consisting of neurofibrillary tangles, neuropil threads and senile plaque neurites which contain paired helical filaments (PHFs) made of hyperphosphorylated microtubule-associated protein tau. A new familial form of presenile dementia with neurofibrillary pathology and no beta-amyloid deposits has been described recently [Sumi et al. (1992) Neurology 42: 120-127]. We have compared the tau pathology in this familial form of presenile dementia with that of AD. To this end we have used electron microscopy, immunoblotting and immunohistochemistry with phosphorylation-dependent (PHF1, AT8, AT100, AT180, AT270, 12E8) and phosphorylation-independent (BR133, BR134) anti-tau antibodies. We show that in the two diseases dispersed PHFs are structurally, biochemically and immunologically identical; they are stained by all anti-tau antibodies used and on immunoblots PHF-tau appears as three major bands of 60, 64 and 68 kDa. However, while the anti-tau antibodies stain neurofibrillary tangles, neuropil threads and neuritic plaques in AD brain, no neuritic plaques are found in familial presenile dementia. These results indicate that in the two diseases tau undergoes the same modifications; they confirm that neurofibrillary tangles and neuropil threads like those in AD can exist independently of beta-amyloid deposits and that their presence is associated with dementia.

Pick's disease (PD) brains were examined immunohistochemically for the expression of antigens known to be associated with Alzheimer's disease (AD) lesions. Most antibodies which label intracellular neurofibrillary tangles (NFTs) in AD were found to stain Pick bodies (PBs). Among them was the monoclonal antibody A2B5, which is known to recognize neuronal surface gangliosides. This result indicates that membrane proteins are probably incorporated into PBs as into NFTs. However, PBs, in contrast to NFTs, showed a paucity of staining for heparan sulfate glycosaminoglycan and basic fibroblast growth factor (bFGF). Staining for midkine, seen in senile plaques in AD, was not seen in PD. The relative lack of staining for these two neurotrophic factors in PD brain may reflect underlying mechanisms which are distinct from those in AD. We also describe two glial abnormalities in PD: glial fibrillary tangles and clusters of granules positive for the complement protein C4d in the hippocampal dentate fascia. These are presumably related to complement-activated oligodendroglia, and both pathological structures are more abundant in advanced cases, suggesting that they may be hallmarks of the disease progression.

Amyloid fibrils in senile plaques of the brain of patients with senile dementia or Alzheimer's disease combined specifically with horseradish peroxidase (HRPO)-labeled rabbit anti-human IgG. Light and electronmicroscopic immunoperoxidase technique was used to prove this. The fact may mean that immunological factors were involved in the pathogenesis of amyloid fibrils in the senile plaques, and probably also in that of senile dementia or Alzheimer's disease.

Ballooned neurons are histological features of several neurodegenerative diseases of the central nervous system. We describe the immunocytochemical staining of ballooned neurons in Pick's disease, unclassified dementia, corticonigral degeneration, pigment-spheroid degeneration and Alzheimer's disease. In all of these conditions the ballooned neurons contain phosphorylated epitopes recognized by monoclonal antibodies to neurofilaments, but not epitopes unique to Alzheimer neurofibrillary tangles and Pick bodies. The morphological features and immunohistochemical properties of ballooned neurons in these disorders bear resemblance to swollen neurons produced by neurotoxins that impair axoplasmic transport of neurofilaments. This finding, by analogy, suggests that impaired axoplasmic transport of neurofilaments may be a common mechanism in various dementing neurodegenerative diseases.

We used rabbit antisera to the 210,000; 155,000; and 70,000 mol. wt. neurofilament - polypeptides and monoclonal antibodies (BF 10; RT97) known to react with human neurofilaments in an immunohistochemical study of neuronal changes in Pick's disease and in senile dementia of the Alzheimer type. Pick bodies as well as neurofibrillary tangles and neurites showed strong reactivity with the monoclonal antibodies but remained unlabeled when treated with the rabbit polyclonal antisera. Our results indicate that the stained material in Pick bodies share antigenic determinants with neurofibrillary tangles and neurofilaments.

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.

Immunoperoxidase techniques were used to obtain information about the possible presence of serum factors in senile plaques. We found only in plaques consisting of an amyloid core surrounded by a corona of degenerating neurites small amounts of IgG and light chains (kappa and lambda). These immunoglobulins were principally localized in the corona and not in the central amyloid core. Further it was found that all plaques contain the complement factors C1q, C3b, C3c, C3d and C4. Senile plaques lacked C5, C3 pro-activator and properdin. The possible significance of these findings in the genesis of the senile plaques and amyloid formation is discussed.

The brains of 43 patients, some with various neurological disorders, other controls, were examined for herpes simplex virus (HSV) antigen using immunoperoxidase technique. The three patients with herpes simplex encephalitis shared a pattern of staining, consistent with that reported previously. However, of the other 40 patients, only two (one a patient with Alzheimer's disease, the other a control patient) showed areas of brain positive for HSV antigen (VA). In the patient with Alzheimer's disease VA was present within nerve and glial cells of the amygdala, within oligodendrocytes of the optic and olfactory tracts and in macrophages within the temporal cortex hippocampus and cerebellum. In the control patient VA was seen only in oligodendrocytes of optic chiasma and olfactory tract. The scarcity of these findings suggests "coincidental disease" processes within these two patients and means that any hypothesis implicating HSV as an aetiological agent in degenerative disease must still remain extremely speculative.

Using a fluorescent antibody technique, sections of the brains of patients with senile dementia or Alzheimer's disease containing senile plaques were treated with rabbit antihuman immunoglobulins labelled with FITC (fluorescein isothiocyanate, BBL). The senile plaques and the cerebral amyloid angiopathy (drusige Entartung, Scholz, 1938) in the brains of patients with senile dementia or Alzheimer's disease showed specific fluorescence. Control sections from the brains of a girl who died from carcinoma of the stomach and of a female schizophrenic who died from lung abscess, showed only slight fluorescence in a few vessel walls. The presence of components or fragments of immunoglobulins in a senile plaques may mean that immunological factors are involved in their pathogenesis and probably also in that of senile dementia and Alzheimer's disease.