A Quantitative and Qualitative Analysis of Prion Protein Immunohistochemical Staining in Creutzfeldt-Jakob Disease Using Four Anti Prion Protein Antibodies

Creutzfeldt-Jakob disease (CJD) is the most common spongiform encephalopathy affecting humans. Prion protein (PrP) immunohistochemistry may be useful for studying the localization of prion protein and assessing its role in CJD, the accumulation of a specific protease resistant PrP isoform being apparently pathognomic to the spongiform encephalopathies. However, a number of factors influence the results of immunostaining, making interpretation and comparisons between the staining of different PrP antisera difficult. This study has examined qualitatively and quantitatively the staining produced by four antisera raised to a variety of prion protein homologues in two cases of CJD and two age-matched controls. Quantitative analysis was provided through the use of custom designed image analysis software. Kuru, granular and multicentric plaques, cellular, perivacuolar and white matter PrP deposits were observed in CJD cases with all four antisera. No significant immunostaining was seen in the control tissue. Some antibody specific staining patterns were observed qualitatively; however, quantitative analysis showed statistically significant correlations between all the antisera on the diseased brain tissue. Prion protein immunohistochemistry is thus useful in interpreting patterns of protein distribution in diseased brain but care may be required in interpreting the results of a single antibody.     

Deposition of the prion protein (PrP) during the evolution of experimental Creutzfeldt-Jakob disease

We studied the immunocytochemical distribution of the prion or proteinase-resistant protein (PrP) during the evolution of experimental Creutzfeldt-Jakob disease (CJD) in mice. Fifty-one brains were collected up to 22 weeks following intracerebral inoculation with the Fujisaki strain of the CJD agent. Slides were also immunostained for apolipoprotein E (apoE) and glial fibrillary acidic protein. Vacuolar changes with focal astrocytosis first occurred around the needle track at week 2 and later spread along white matter tracks. Until week 12, changes were asymmetrical, affecting more the side of inoculation. Spongiform change and astrogliosis spread subsequently to the gray matter. Time course and intensity of spongiform change and immunocytochemistry for PrP were discrepant: in most brain regions, severe vacuolation preceded immunocytochemically detectable PrP accumulation. PrP deposits in form of small dots were first detectable at week 6 in the area surrounding the needle track. After week 7, plaque-like amorphous PrP deposits were observed in white matter pathways. Finally, PrP was detectable also in basal ganglia and in the dorsal hippocampus (week 13) and in the neocortex (week 17), as the synaptic type of PrP immunopositivity. In the hippocampus, diffuse PrP deposits paralleled spongiform change, while in the cortex severe vacuolation was accompanied only by weak synaptic PrP deposits. Immunocytochemically detectable apoE was restricted to compact plaque-type PrP deposits after week 15. We conclude that disease-specific neuropathology spreads from the needle track along white matter pathways towards the gray matter; in this model, there is some discrepancy between development of tissue pathology and immunocytochemically detectable deposition of PrP. Immunocytochemically detectable apoE deposition follows PrP accumulation. Received: 22 December 1998 / Revised, accepted: 6 April 1999     

Sporadic Creutzfeldt-Jakob disease: the extent of microglia activation is dependent on the biochemical type of PrPSc

In prion-related encephalopathies, microglial activation occurs early and is dependent on accumulation of disease-specific forms of the prion protein (PrPSc) and may play a role in nerve cell death. Previously, we found that different types of PrPSc (i.e. type 1 and type 2) coexisted in approximately 25% of patients with sporadic Creutzfeldt-Jakob disease (CJD); and a close relationship was detected between PrPSc type, the pattern of PrP immunoreactivity, and extent of spongiform degeneration. To investigate whether microglial reaction is related to the biochemical type and deposition pattern of PrPSc, we carried out a neuropathologic and biochemical study on 26 patients with sporadic CJD, including all possible genotypes at codon 129 of the prion protein gene. By quantitative analysis, we demonstrated that strong microglial activation was associated with type 1 PrPSc and diffuse PrP immunoreactivity, whereas type 2 PrPSc and focal PrP deposits were accompanied by mild microglia reaction. These findings support the view that the phenotypic heterogeneity of sporadic CJD is largely determined by the physicochemical properties of distinct PrPSc conformers.     

Prominent stress response of Purkinje cells in Creutzfeldt-Jakob disease

To examine the role of stress-related 70-kDa heat shock proteins (Hsp-s) in Creutzfeldt-Jakob disease (CJD), we performed immunocytochemistry to detect Hsp-72 and Hsp-73, together with the abnormal (PrP(Sc)) and the presumed cellular form (PrP(C)) of the prion protein, and TUNEL method to measure cellular vulnerability in different brain regions in CJD and control cases. While Hsp-73 showed uniform distribution in all the examined samples, an increase in the number of Purkinje cells with prominent accumulation of Hsp-72 in the CJD group was observed. These neurons also showed intense PrP(C) staining, but TUNEL-positive nuclei were only detected in the granular (Hsp-72-negative) cell layer. Fewer cells of the inferior olivary nucleus were immunoreactive for Hsp-72 in CJD than in control cases, and regions showing severe spongiform change and gliosis exhibited fewer Hsp-72-immunoreactive neurons. Our results indicate that accumulation of the inducible Hsp-72 in certain cell types may be part of a cytoprotective mechanism, which includes preservation of proteins like PrP(C).     

Prion protein glycotype analysis in familial and sporadic Creutzfeldt-Jakob disease patients

Creutzfeldt-Jakob disease (CJD) and other transmissible spongiform encephalopathies (TSEs) are characterised by the accumulation of a pathological conformer of PrP, named PrPsc. Molecular weight and glycosylation of the protease-resistant core of PrPsc (PrP27-30) are heterogeneous in different forms of TSEs. We analysed PrP27-30 glycotypes in a large number of TSE-affected patients: 50 sporadic CJD (sCJD), 1 iatrogenic CJD, 1 Gerstmann-Str?ussler-Scheinker syndrome (GSS) with the Pro102Leu mutation of PrP, 3 familial CJD (fCJD) with the Glu200Lys mutation and, for the first time, 7 fCJD with the Val210ll3e mutation. All patients were screened for the polymorphic codon 129 of the PrP gene. PrP27-30 deglycosylation and PrPsc immunohistochemistry were performed in selected cases. We found that two PrP27-30 glycotypes (type 1A and type 2A) are produced in sCJD. Type 1A is more frequently associated with methionine than valine in position 129. Type 1A is also formed in Val210lle fCJD. In Glu200Lys fCJD and GSS patients, we found that PrP27-30 has the same mobility of type 1 but different glycosylation ratios (type 1B). Our findings indicate that the polymorphic residue 129 of PrP has a leading role in determining the proteinase degradation site of PrPsc while mutant residues 102 or 200 influence only the glycosylation pattern.     

Creutzfeldt-Jakob病5例临床研究

目的　通过临床病例和实验室资料的总结 ,提高对CJD的认识和诊断水平。方法　对 5例CJD病患者的临床表现、影像学特点、脑电图改变、病理学变化、动物接种和基因检测等资料进行分析和总结。结果5例均为亚急性起病 ,有迅速进展的痴呆和肌阵挛 ,1例MRI显示双侧尾状核长T2 信号 ,脑电图均明显异常。 3例病理检查均符合典型CJD的病理学特点。结论　应当提高临床医师对本病的认识 ,根据典型的临床和EEG表现 ,特别是MRI特点以及CSF中 14- 3- 3蛋白的检测 ,争取实施无创性检查 ,以早期作出诊断     

Creutzfeldt-Jakob disease and other human transmissible spongiform encephalopathies. Part II

The second part of this work presents the neuropathological problems of the Creutzfeldt-Jakob disease and basic informations about other human prion diseases. General problems of prion diseases and clinical symptoms of Creutzfeldt-Jakob disease were presented in the first part. Prion diseases are also known as transmissible cerebral amyloidoses (TCA) or transmissible (subacute) spongiform encephalopathies (TSE, SSE). There are following human TSE's: Creutzfeldt-Jakob disease (CJD)--the most frequent TSE, and its new variant (vCJD)--a result of BSE's transmission into human, sometimes treated as a separate disease; also: Gerstmann-Str?ussler-Scheinker syndrome (GSS) that may be a variant of familial CJD, kuru--probably a result of sporadic CJD's transmission by cannibalism, and fatal familial insomnia (FFI). Their clinical symptoms (and especially of the CJD), are nonspecific and sometimes variable. The imaging, EEG and other laboratory tests are not specific either. Neuropathological studies are needed but their interpretation may be equivocal. TSE's are characterised by the neurodegenerative process with characteristic spongiosis. However, vacuolisation--similar as in TSE-spongiosis--may occur in some CNS's disorders and in the case of putrescent brain tissue. In some cases of CJD, particularly those of long duration, the neuronal loss and astrocyte proliferation can mask the presence of spongiform changes, especially when vacuoles are not numerous. The only certain diagnostic marker for TSE is PrP(Sc), prion protein, presently believed to be a direct cause for all TSEs (TCAs). The PrP(Sc) has a dominant beta-sheet amyloid structure which makes its detection by immunohistochemical procedure possible only with special pretreatment, e.c.: hydrolytic autoclaving, hydrated autoclaving, incubations: formic acid (or guanidine thiocyanate) pretreatment, also combined pretreatments. These methods are standard diagnostic procedures for transmissible cerebral amyloidoses.     

In situ hybridization analysis of PrP mRNA in human CNS tissues

Expression of the prion protein gene (Prnp) and production of the PrP protein are essential requirements for acquisition and spread of transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease (CJD) in humans. Here we have developed an in situ hybridization method for use on human post-mortem central nervous system (CNS) tissues in order to determine those cell which are transcribing the Prnp gene and thus expressing PrP mRNA. Tissues from 11 adult individuals (age range 21-79 years) were analysed. Similar to previous studies in other animal systems, it was shown that PrP production occurs primarily in neuronal populations throughout the human brain. Neurones of the hippocampus, cortex, thalamus, cerebellum and medulla all synthesize PrP mRNA at readily detectable levels. No age-related differences were observed between the cases studied. It was also found that the ependymal cells produced PrP mRNA; these were the only non-neuronal cell type expressing the Prnp gene in the CNS. It is hoped that the information produced here will be helpful in understanding the pathology associated with CJD and other prion diseases in humans.     

Elk with a long incubation prion disease phenotype have a unique PrPd profile

The transmissible spongiform encephalopathies (TSEs) invariably result in fatal neurodegeneration and accumulation of PrP, an abnormal form of the host prion protein PrP, encoded by the PRNP gene. A naturally occurring polymorphism (methionine/valine) at PRNP codon 129 is associated with variation in relative disease susceptibility, incubation time, clinical presentation, neuropathology, and/or PrP biochemical characteristics in a range of human TSEs. A methionine/leucine polymorphism at the corresponding site in the Rocky Mountain elk PRNP gene is associated with variation in relative susceptibility and incubation time in the cervid TSE chronic wasting disease. We now report that elk lacking the predisposing 132-methionine allele develop chronic wasting disease after a long incubation period and display a novel PrP folding pattern.     

Creutzfeldt-Jakob disease in Austria.

Between 1969 and 30 September 1995, 79 Austrian patients had Creutzfeldt-Jakob disease (CJD) diagnosed neuropathologically by necropsy or biopsy. The annual incidence has significantly increased in recent years (average 0.18 per million in 1969-85, and 0.67 per million in 1986-94; estimate for 1995: 1.5 per million). Also, the percentage of patients with CJD over 70 years at death increased significantly until 1989 but is since in decline. There is no regional clustering, familial occurrence, or recognised iatrogenic risk. One patient had a 10 year history of intramuscular injection of purified bovine RNA preparation (Regeneresen) from various organs including the brian. The ages at death are symmetrically distributed around the median of 64 years. The median duration of disease is four months. Most patients (76%) died within six months of onset. Retrospectively, 86% of patients fulfilled clinical criteria of probable or possible CJD. Neuropathology showed the classic triad of spongiform change, astrogliosis, and neuronal loss in most cases. Two cases did not show unequivocal tissue alterations, but anti-PrP immunocytochemistry detected PrP deposits also in these cases. It is concluded that the recent rise in incidence of CJD in Austria most likely reflects increased awareness and diagnosis of CJD rather than a real increase. As bovine spongiform encephalopathy (BSE) has not been reported in Austria, the data do not support a link between a rise in incidence of sporadic CJD and BSE.     

Increased expression of water channel aquaporin 1 and aquaporin 4 in Creutzfeldt-Jakob disease and in bovine spongiform encephalopathy-infected bovine-PrP transgenic mice

Spongiform change is a cardinal feature in transmissible spongiform encephalopathies, including Creutzfeldt-Jakob disease (CJD) and bovine spongiform encephalopathy (BSE). It is characterized by swelling of the neuronal processes and vacuolization of the neuropil, leading to increased intraneuronal water content. The present study examines, by gel electrophoresis and Western blotting, the expression levels of the water channels aquaporin 1 (AQP1) and aquaporin 4 (AQP4) in the frontal cortex (area 8) homogenates of sporadic CJD cases (six men, four women; seven cases with methionine/methionine at codon 129 and PrP type 1; two cases with valine/valine at codon 129 and PrP type 2, and one case methionine/valine at codon 129 and PrP type 1) compared with age-matched controls, and cases with Alzheimer’s disease (AD, stage VI of Braak and Braak) and diffuse Lewy body disease (DLB). AQP1 and AQP4 protein levels were also studied in the cerebral cortex of BSE-infected bovine-PrP transgenic mice (BoPrP-Tg110 mice) examined at 60, 150, 210 and 270 days post-inoculation (dpi) compared with healthy brain-inoculated control mice. Quantitative densitometry of AQP bands normalized for β-actin was analyzed using Statgraphics plus 5.0 software from ANOVA and LSD statistical tests. Significant increased expression levels of AQP1 (as revealed with two different antibodies) and AQP4 were seen in CJD, but not in advanced AD and DLB cases when compared with controls. Immunohistochemistry revealed that AQP1 and AQP4 were expressed in astrocytes in diseased cases. No modifications in the expression levels of AQP1 and AQP4 were observed in BSE-infected bovine-PrP transgenic mice at 60, 150 and 210 dpi. However, a significant increase in the expression levels of AQP1 and AQP4 was found in mice at 270 dpi, the time corresponding with the appearance of PrP^res immunoreactivity in Western blots and typical spongiform lesions in the brain. Together, these findings show increased expression of water channels in the brain in human and animal prion diseases. These modifications may have implications in the regulation of water transport in astrocytes and may account for an imbalance in water and ion homeostasis in prion diseases.     

Creutzfeldt-Jakob disease and other human transmissible spongiform encephalopathies. Part I

In the first part of this work the main problems of prion diseases--also called transmissible cerebral amyloidoses (TCA) or subacute (transmissible) encephalopathies (SSE, TSE)--and clinical symptoms of Creutzfeldt-Jakob disease are presented. Some problems of neuropathology of Creutzfeldt-Jakob disease and basic informations about other human prion diseases will be presented in the second part. The growth of the interest in prion diseases during last years is caused by the problem of bovine spongiform encephalopathy (BSE or "mad cow disease") and its transmission into a human. The new variant of Creutzfeldt-Jakob disease (nvCJD) has appeared. Prion diseases: Gerstmann-Str?ussler-Scheinker syndrome (GSS), kuru, fatal familial insomnia (FFI) and particularly the most frequent of them--Creutzfeldt-Jakob disease (CJD)--have nonspecific, sometimes variable clinical (psychopathological and neurological) symptoms. The imaging, EEG, cerebrospinal fluid tests and other laboratory tests are not specific either and their diagnostic value is limited. Neuropathological studies are needed but their interpretation is often difficult. The only certain diagnostic marker for TSE is the presence of PrP(Sc), the prion protein, which is presently believed to be a direct cause for all transmissible cerebral amyloidoses (TCA).     

Ubiquitin immunocytochemistry in human spongiform encephalopathies

The distribution of ubiquitin was studied by immunocytochemistry in eight cases of human spongiform encephalopathy and compared with the findings in seven age-and sex-matched cases of Alzheimer's disease and six non-demented control cases. The results were also compared with the immunocytochemical distribution of prion protein and the lysosomal aspartic protease cathepsin D. In the human spongiform encephalopathies, ubiquitin immunoreactivity was found in a punctate distribution at the periphery of prion protein amyloid plaques and in a finely granular pattern in the neuropil around and within areas of spongiform change. Cortical nerve cells contained scanty ubiquitinated dot-like inclusions, and occasional microglia around the areas of spongiform change also gave a positive staining reaction for ubiquitin, as did multiple irregular thread-like structures in the neuropil and white matter. The ubiquitin-containing structures at the plaque periphery in human spongiform encephalopathies resemble the neuritic processes at the periphery of the senile plaque in Alzheimer's disease. The granular positivity for ubiquitin associated with areas of spongiform change closely resembles the pattern of immunostaining seen with the antibodies to the prion protein and cathepsin D, consistent with the reported accumulation of ubiquitinated proteins and prion protein in lysosomes in the murine scrapie model. Further studies are required to investigate the role of lysosomes in this group of disorders, and to study the localization of other cell stress proteins and prion protein in spongiform encephalopathies.     

Creutzfeldt‐Jakob disease

This review will explore the clinical and pathological findings of the various forms of Creutzfeldt‐Jakob disease (CJD). Clinical findings of CJD are characterized by rapidly progressive cognitive dysfunction, diffusion‐weighted magnetic resonance imaging (DWI) hyperintensity, myoclonus, periodic sharp‐wave complexes on electroencephalogram and akinetic mutism state. Neuropathologic findings of CJD are characterized by spongiform changes in gray matter, gliosis—particularly hypertrophic astrocytosis—neuropil rarefaction, neuron loss and prion protein (PrP) deposition. The earliest pathological symptom observed by HE staining in the cerebral cortex is spongiform change. This spongiform change begins several months before clinical onset, and is followed by gliosis. Subsequently, neuropil rarefaction appears, followed by neuron loss. Regions showing fine vacuole‐type spongiform change reflect synaptic‐type PrP deposition and type 1 PrP^Sc deposition, whereas regions showing large confluent vacuole‐type spongiform changes reflect perivacuolar‐type PrP deposition and type 2 PrP^Sc deposition. Hyperintensities of the cerebral gray matter observed in DWI indicate the pathology of the spongiform change in CJD. The cerebral cortical lesions with large confluent vacuoles and type 2 PrP^Sc show higher brightness and more continuous hyperintensity on DWI than those with fine vacuoles and type 1 PrP^Sc. CJD cases showing diffuse myelin pallor of cerebral white matter have been described as panencephalopathic‐type, and this white matter pathology is mainly due to secondary degeneration caused by cerebral cortical involvement, particularly in regard to neuron loss. In conclusion, clinical and neuroimaging findings and neuropathologic observations are well matched in both typical and atypical cases in CJD. The clinical diagnosis of CJD is relatively easy for typical CJD cases such as the MM1‐type. However, even in atypical cases it seems that clinical findings can be used for an accurate diagnosis.     

Creutzfeldt-Jakob disease with tubulovesicular structures: an ultrastructural study.

Tubulovesicular structures (TVS) have been consistently observed in brain tissue of the transmissible spongiform virus encephalopathies such as natural and experimental scrapie, bovine spongiform encephalopathy and experimentally induced Creutzfeldt-Jakob disease (CJD). TVS were recently demonstrated in 3 cases of naturally occurring CJD. We report here the presence of TVS in another human brain with CJD, as detected in all 3 specimens by thin section electron microscopy. Their occurrence in all types of spongiform encephalopathies, irrespective of the affected host and the strain of infectious agent, emphasizes their biological significance.     

Reactive microgIia in Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is characterized by a loss of neurons accoinpanied by astrogliosis and spongiform changes in the neuropil. It has been recognized that reactive inicroglia occur in CJD but little is known about the regional distribution and extent of the microglial activation. We have. therefore, examined six brains from cases of sporadic CJD by immunohistochemical labelling of grey and white matter microglia froin frontal, parietal. temporal. and occipital lobes, striatum, thalamus, cerebellum and brain stem with RCA-I, LCA. CD68. HIA-DR. and HAM56. Microglial activation occurred in the grey matter where astrogliosis and prion protein (PrP) deposits were prominent. Processes of activated microglia surrounded the outer rim of spongy vacuoles. A diffuse microglial response was seen in the white matter that was immunophenotypically different from grey matter. Double-labelling with microglial marlters and anti-PrP showed that activated inicroglia did not contain PrP-immunoreactivity. Therefore a primary role of microglia in PrP processing seem unlikely. Activated inicroglia may contribute to neuronal damage in CJD due to their cytotoxic potential.     

Does PRNP gene control the clinical and pathological phenotype of human spongiform transmissible encephalopathies?

BACKGROUND: Human spongiform transmissible encephalopathies (TSE) are a group of neurodegenerative diseases caused by a transmissible not yet recognized agent; their distinctive neuropathological features are astrocytosis, spongiform lesions of the neuropil, neuronal loss and occasionally amyloid plaques in the cortical and subcortical gray matter. TSE are biochemically characterized by the deposition in the nervous system of an amyloid-type protein, PrPres derived from the post-translational modification of a normal protein, PrPsen. The expression of this protein is controlled by the PRNP gene mapped on chromosome 20 in man. A number of point mutations of the PRNP gene have been described in the familial forms of these TSE. Some of these mutations have been associated with differences in the phenotypic expression of the disease. MATERIAL AND METHODS: This study was designed to verify whether it was possible to identify a selective phenotype depending upon a given PRNP modified genotye; for this purpose, a group of familial TSE cases (CJD 210ILE, CJD 201LYS, FFI 178ASN) were selected and their neuropathological profiles have been compared with those of a large series of sporadic CJD cases. RESULTS: No significant differences were found between the topography and severity of lesions in the cerebral cortex, cerebellum, hippocampus, basal ganglia and thalamus between the two groups. Two differences were found: the clinical duration of the disease which appeared significantly (p = 0.02) shorter in the 210ILE-mutated cases compared to that of non-mutated sporadic cases. The highly selective vulnerability of thalamus in FFI showing a severe pathology especially in its dorso-medial part in comparison with that of the sporadic CJD cases. CONCLUSION: The results of this study confirm that the different polymorphism at codon 129 of the PRNP gene, which could be involved in the structural "domains" of human PrP, might modulate the pathological phenotype of TSE.     

Le réseau de surveillance de la maladie de Creutzfeldt-Jakob

IntroductionTransmissible spongiform encephalopathies (TSE) have been under epidemiological surveillance in France and in Europe since the early 1990s. The observation of iatrogenic Creutzfeldt-Jakob disease (CJD), the outbreak of bovine spongiform encephalopathy (ESB) and its probable transmission to many species gave rise to the surveillance which remains warranted by the emergence of a variant of CJD (vCJD), in 1996.State of artIn France, epidemiological surveillance is coordinated by the InVS which receives input from cases notifications addressed to INSERM Unit 708 directly by clinicians or more often following requests for 14-3-3 detection in CSF. All suspected cases are followed up until a final diagnosis is established. Thanks to the effectiveness of the French network of neuropathology, autopsies are performed in more than half of patients who die with a diagnosis of suspected CJD. Diagnostic criteria allow comparison of the incidence of the different forms of the disease in all countries with a system of surveillance. Sporadic CJD is the most frequent form of the disease with more than 80% of the cases. Its origin remains unknown. To date, cases of iatrogenic CJD referred to the French surveillance network have been caused by dura mater grafts or human growth hormone treatments administrated in the 1980s. Ten percent of TSE are of genetic origin with an autosomic dominant transmission of a mutation or an insertion located on the PRNP gene. The most recent form of the disease is vCJD which is a new form, first described in the United Kingdom in 1994.Prospect and conclusionActive epidemiological surveillance remains a timely issue, particularly in France, because of the development of new cases of iatrogenic CJD after human growth hormone treatment. It is of importance in France and worldwide because of the emergence of post-transfusional cases of vCJD and the possible appearance of vCJD in persons with valine-valine or methionine-valine genotypes at codon 129.     

Sporadic Creutzfeldt-Jakob disease: co-occurrence of different types of PrP(Sc) in the same brain

Phenotypic heterogeneity of sporadic Creutzfeldt-Jakob disease (CJD) has been linked to biochemically distinct types of the protease-resistant form of the prion protein (type 1 and type 2 PrP(Sc)). We investigated 14 cases of sporadic CJD and found that both type 1 and type 2 PrP(Sc) coexisted in 5 subjects. The distinct PrP(Sc) isoforms were associated with different patterns of PrP deposition and severity of spongiform changes, suggesting that the PrP(Sc) type plays a central role in determining the neuropathologic profile of CJD.     

Brain biopsy in Creutzfeldt-Jakob disease: evolution of pathological changes by prion protein immunohistochemistry

The formation of protease-resistant prion protein (PrPsc) is considered to be an early event in the pathogenesis of Creutzfeldt-Jakob disease (CJD) and hence its demonstration in brain biopsies by immunohistochemistry is considered diagnostic. We analysed eight brain biopsies from the frontal cortex collected from different parts of India from cases diagnosed as CJD on clinical and pathological grounds for the expression of prion protein (PrP). The duration of illness in these cases varied from 2 months to 1 year. Immunohistochemistry was carried out on paraffin sections using two different clones (KG9 and 3F4) of monoclonal antibodies to PrP. Although all eight cases showed classical features of spongiform encephalopathy of varying severity, only five of the eight cases revealed PrP(sc) in the brain tissue. The immunolabelling was focal and all areas with spongiform change were not labelled. A temporal evolution in the staining pattern was evident - particulate diffuse labelling (synaptic type) in early stages (2 months), perivacuolar deposits in intermediate stages (5-6 months), and dense plaques in late stages (12 months).