Identification with a Monoclonal Antibody of a Phylogenetically Conserved Brain-Specific Determinant on a 130,000 Molecular Weight Glycoprotein of Human Brain

Human brain glycoproteins depleted of Thy-1 antigen were used to immunise Balb/c mice for monoclonal antibody production. The F3-87-8 antibody described in this paper interacts with a determinant present in large amounts on all human brain subregions studied (cerebral cortical grey matter, white matter, caudate, thalamus, dentate nucleus, putamen, cerebellar cortex) but absent from all other tissues examined (liver, heart, kidney, spleen, thymus, lymph node, erythrocyte, adrenal gland, and peripheral nerve). The determinant is conserved in mammalian evolution, as the brains of the rat and dog have amounts equal to that found in human brain. Balb/c mouse brain has approximately one-third as much antigen activity as these other mammalian brains, whereas brains of the frog and chicken have no detectable antigenic activity. Developmental studies showed that 16-week human foetal brain and neonatal dog brain had little or no antigen activity, indicating a dramatic increase in the amount of the determinant with brain maturation. Biochemical studies showed that the F3-87-8-bearing molecule was a major sialoglycoprotein of human brain with an apparent molecular weight of 130,000. It was shown by immunofluorescence to be particularly localised in what appeared to be fibre tracts in the thalamus and basal ganglia, and in the dentate nucleus, although all regions including grey matter were stained.