A FUNCTIONAL-ROLE FOR CORPORA-AMYLACEA BASED ON EVIDENCE FROM COMPLEMENT STUDIES

Few theories have been advanced for the production of corpora amylacea (CA) by the normal ageing brain and by the CNS under various neurolog ical conditions. Proteins derived from neurons and oligodendrocytes ar e found in CA and to understand their origins brain tissue from patien ts with Alzheimer's disease (AD), multiple sclerosis (MS) and Pick's d isease (PD) were tested for complement activity. All CA were immunopos itive for antisera to classical pathway-specific components, the activ ation products C3d and the terminal complement complex (TCC), the C3 c onvertase regulator membrane cofactor protein (MCP) and the fluid phas e regulators S-protein and clusterin. CA were immunonegative for the a lternative complement pathway proteins and the complement regulators, decay accelerating factor (DAF) and CD59. Western immunoblotting of is olated solubilized CA from the same tissues demonstrated a weak band f or MCP but TCC was more easily shown by immunoprecipitaton. A filament ous fringe around CA, probably of astrocytic origin, was also immunopo sitive for complement factors. CA consist of an inert mucopolysacchari de matrix encasing ubiquitinated proteins, resulting from death of and damage to neurons, myelin and oligodendrocytes. A function of CA, the refore, could be to prevent the recognition of these immunogenic prote ins by lymphocytes and microglia and thus protect the CNS from further injury. (C) 1995 Academic Press Limited