s90 THIRD INTERNATIONAL CONFERENCE ON ALZHEIMER’S DISEASE

the pericyte processes extended into the brain parenchyma. Thus, microglia are intimately associated with neuronal, parenchymal, and vascular accumulations of amyloid.

Micro&a play a role in the AD pathogenetic process. They apparently penetrate their processes into NFT-laden neurons (perhaps to phagocytose them piecemeal in a process called neuronophagia), and may be responsible for the changed epitopes exhibited on the extracellular-NFT. In addition, the microglial pericyte association with amyloid suggests that this cell type(s) may be involved in a similar fashion in the processing of both vascular and parenchymal amyloid. (CA AD Prog., AG07127, AG05142, AG07624).

355 DECREASED SECRETION OF CYSTATIN C VARIANT IN MONOCYTES FROM INDIVIDUALS WITH THE MUTATION CAUSING HEREDITARY CYSTATIN C AMYLOID ANGIOPATHY (HCCAA) AND STROKE

L. Thomteinsson,‘) G. Georgssor~,~) B. &@sson,4) M. Bjamad6ttir.1) 1. 61afsson,5) 6. Jensson.‘) and G. Gubmundsson.*)

Dept. of Med. Genetics, The Blood Sanklj. Dept. of Neurob2) Narionaf Univ. Hosp., Inst. for Exp. P&o/., Keklu?), Science /nsL4) Univ. of Iceland, Reykjavik fcelano’, Dept. of C/in Chem. Univ. Hosp. Lund Sweden5/.

Hereditary cystatin C amyloid angiopathy (HCCAA) causes fatal cerebral hemorrhage in Icelandic families. A point mutation in exon 2 of the cystatin C gene leads to formation of a variant protein with leucine to glutamine substnution at position 68 in the cystatin C molecule. This variant of the cystatin C molecule, which normally functions as a potent cysteine proteinase inhibitor forms the amybid deposits in the central nervous system (CNS) and some other tissues. The pathogenesis of the deposition of the variant cystatin C as amyloid is not known. The substitution of one amino acid does apparently change the physical characteristics of the protein in such a way that it can not be processed in a regular fashion. In an attempt to localize the fault at cellular level we have studied the synthesis and secretion of cystatin C in blood monocytes from nine carriers of the mutated cystatin C gene (four asymptomatic and five with repeated strokes). Monocytes from blood donors sewed as controls. The quantity of cystatin C in lysed cells and supernatants was determined by the ELISA method, Western blots were done and setected samples immunostained for cystatin C. The ratio of the quantity of cystatin C in lysed cells versus supernatant was in contrast to normal controls higher than 1 in carriers (symptomatic and asymptomatic) of the mutated cystatin C gene. Partial block in the secretion of cystatin C mbht explain the low cerebrospinal fluid levels of cystatin C, a constant feature in individuals carrying the mutant gene. Western blot analysis of the cystatin C synthesized by monocytes of carriers showed it to be of normal size but not truncated as its form found in the cerebral amyloid deposits. lmmunostaining of the cultured monocytes was in general more intense in monocytes from carriers 01 the mutated cystatin C gene than in the controls. An accentuation of the staining was frequently noted perinuclearly and at the cell membrane. A nuclear staining, either diffuse or speckled, was alSo observed in both groups. Cystatin C normally functions as cysteine proteinase inhibitor. It is possible that its bw extracellular concentration could be inadequate to downregulate cysteine proteinases effectively with concomitant increase in tissue damage and brain hemorrhage. The mkxoglia of the CNS are closely related to monocyies and the macrophage cell system are considered to have a signlint role in the generation of amybii formation. Thus, our observations of a partial block in the secretion of cystatin C in monocyles from carriers of the mutant gene may be of relevance for the pathogenesis both of amybid deposls and hemorrhagic phenomenon in HCCAA.

356 EXPRESSION OF TWO ASTROGLIAL MARKERS : THE GFI- AND THE GS IN ALZHEIMER DISEASE. G. Le Prince, C. Fazes, B. Rolland. 1.1. Hauw* and M.Tardv. INSERM U. 282, HBpital H. Mondor. 94010 CRETEIL.FRANCE. *Laboratoire R. Escourole. Hi3pital de la Salp&ri&re. 47, Bd de l’HBpita1. 75651 PARIS.

Degeneration of neurons and amyloi’d deposit formation are associated with an astrocytic gliosis at the senile plaque neighbourhood consisting of numerous reactive astrocytes. These play a critical role in the response of the CNS to any injury. But little is known about the molecular events which take place in the gliosis process. The expression of two astroglial proteins have been investigated : l.The Acidic Protein (GFAP), a 50 kD monomer, the major protein of gliofilaments, a good morphologic astroglial specific marker. 2. The Glutamine Synthtase (GS), an enzymatic protein which plays an important part in the turnover of Ammoniac and Glutamate which have been concentrated by the astrocytes, is a high grade glial metabolic marker.

The aim of the present work was to evaluate these two astroglial markers and their encoding message in Alzheimer postmortem

brain samples. These evaluations have been performed either on frontal and temporal cortex or on Medulla Oblongata. These areas are or are not spared by Alzheimer Disease lesions.

Primarily results underline that the GFAP and its encoding mRNA levels are quite different in areas directly implicated in Alzheimer Disease lesions. Moreover , in one of the proximal areas (temporal cortex) it exists a close correlation between this astroglial marker and the number of neuritics plaques per mm2. Relating to GS and its encoding message, primiraly results point out obvious alterations of GS and its mRNA in the same brain samples.

The postmortem human brain samples were provided by Dr J.J. Hauw (HBpital Pitie Salu&ri&e. Paris.) This wori is supporteb by grants rrom IPSEN foundation for Therapeutic Research of Alzheimer Disease and from France Alzheimer Association.

357 THE SUBCORTICAL GLIAL ZONE AND ITS REACTIONS IN AGING AND ALZHEIIIW’S DISEASE, T.I. Mandybur and P. Olejniczak. Depts of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA.

We have studied the subcortical glial zone (SGZ) which seems to share certain similar reactions with the external cortical glial zone (ECGZ) of the molecular layer (ML). GFAP stained sections of normal human cerebral cortex with neighboring white matter exhibited a concentration of fibrous astroglial cell bodies (AS) and fibers in a zone approximately 0.3-l mm underneath the lamina VI, partly involving also the deeper portions of the lamina VI in all examined cortical areas. The deep cortex, laminas II-V, contained few fibrillary astrocytes.

The density of the AS in SGZ was significantly greater than in the deeper white matter in a given segment of the cortex. In all areas studied, AS counts in the SGZ were about similarly proportionate to those in the ECGZ, although the density of the AS of the SGZ was of lesser degree. Curiously, such zone was not observed about the basal ganglia or other deep gray matter structures. One role of the SGZ could be in providing a sealer to the cortex from the white matter by producing here a denser astrocytic fiber network or just by providing reinforcing fibrous skeleton-for the cortical gray matter and/or the U-fibers.

SGZ is activated in aging and especially in Alzheimer's disease, and this process tends to be synchronous with the increase of glia of the molecular layer.

358 aB-CRYSTALLIN INCREASES IN REACTIVE GLIA IN ALZHEIMER DISEASE, K Renkawek, C.E.M. Voorter, G.J.C.G.M. Bosman, EPA. van Workum and W.W. de Jong. Depts of Neurology and Biochemistry, Universi- ty of Nijmegen, P.O. Box 9101.6500 HB Nijmegen, The Netherlands. Immunoreactivity for aB-Crystallin (aB-CR-IR) was observed in all types of glia cells and in senile plaques (SP) in Alzheimer disease (AD) hippocampus and neocortex. In the control brains olB-CR-IR was found in oligodendroglia. In AD immunoreaction was present in several proliferating astrocytes, but there was no correlation between massively proliferating glial tibrillar acidic protein immunoreactive (GFAP-IR) astroctytes and a relatively small number of aB-CR-IR positive cells. Strong immunoreaction was present in the cells immunoreactive for ferritin and identified as microglia, which were frequently in contact with SP. Preliminary biochemical results obtained by immunoblot- ting showed increased amounts of aB-Crystallin in the cortex and white matter in AD brain as compared with age-matched control. aB-Crystallin is a small heat shock protein (HSP) which in the brain is elevated in the astrocy tea under pathological conditions. It could be suggested that crB-CIystallin appears in unspecifically proliferating aatrocytea independent of the kind of disease. A strong crB-CR-IR has recently been described in Creutieldt-Jakob disease (Renkawek et al. Acta Neuropathol., in press). Our results showed