HUMAN BRAIN‐SPECIFIC ALPHA₂‐GLYCOPROTEIN: PURIFICATION BY AFFINITY CHROMATOGRAPHY AND DETECTION OF A NEW COMPONENT; LOCALIZATION IN NERVOUS CELLS¹

Abstract

Human brain-specific alphaz-glycoprotein was purified by means of Sepharose immunoadsorbents. A further brain-specific protein was found by this method. This component appears to be present in brain in low concentrations only and has been enriched by affinity chromatography. Glial cells of human brain were separated from neurons by a density centrifugation method and four fractions were obtained: neuropil, neuronal perikarya, nuclei and debris. Each fraction was checked by light and phase contrast microscopy to estimate the intactness of the cells and any contamination by other fractions, and also immunologically for determination of brain-specific alphaz-glycoprotein.The results indicate that localization of this brain-specific protein is in the cytoplasm of the glial cells. The results are discussed in terms of a possible role of this protein in the inflammatory response and in some demyelinating diseases.

Nervous system antigens

“…Only traces were present in grey matter and none could be identified in peripheral nerve. Even though trace amounts have been demonstrated in nerve cells (Warecka et al 1972) most of the data suggest that the protein is localized in glia.…”

Human glioma tumour-associated antigens

“…GFAP disappears from tumour cells after several passages in culture [41]. a2-Glycoprotein is another glia-specific protein found predominantly in oligodendrocytes [43] and associated with gliogenous tumours; its amount also correlates inversely with the malignancy of the tumour [44]. S100 protein is present in normal brain [29], and $100 levels in glial tumour tissue are inversely proportional to the degree of malignancy [7,12].…”