NEW IMMUNOCYTOCHEMICAL EVIDENCE FOR A NEURONAL OLIGODENDROGLIAL ORIGIN FOR CORPORA-AMYLACEA/

Studies employing a bank of antisera applied to sections of LR White e mbedded AD and normal ageing brain tissue, may throw new light on the derivation of CA. Conspicuous levels of immunoreactivity were found in the CA of both tissues with markers for oligodendrocytic proteins suc h as antisera against myelin basic proteolipid protein, galactocerebro side and myelin/oligodendrocyte glycoprotein. CA were unreactive with MRC OX-42, a marker for microglia and macrophages. In a previous publi cation [22] we demonstrated that the much more abundant CA in the brai ns of Alzheimer's disease (AD) sufferers, although slightly more varie d in their immunoreactivity than those found in normally ageing contro ls, were universally immunoreactive with anti-tau, a neuronally derive d protein and often also contained amyloid. The cores of CA were not i mmunoreactive with anti-GFAP, suggesting a lack of involvement with as trocytes. Our results now show that in addition to amyloid and neurona l proteins, a significant proportion of the content of CA is derived f rom oligodendrocytes and/or myelin. The substantial Fe peak previously reported [22] following X-ray microanalysis of CA was probably due to ferritin. However, immunostaining with antisera to ferritin showed th at high ferritin immunoreactivity was common to both micro- and macrog lia as well as CA. More significantly, the immunoreactivity of CA with anti-ubiquitin [22] suggests that degeneration of neuronal/oligodendr ocytic elements may precede CA formation.