Preparation, derivation and partial characterization of organ-specific antigens from human brain.

Fractional ethanol precipitation was used to prepare a concentrate of brain-specific components of thermostable (BE) antigens derived from heated extract of human brain. Chromatography on DEAE-cellulose yielded a well-defined acidic protein peak containing brain-specific material corresponding to a minimum of two brain-specific components. Preparation of a protein fraction (RSP) from unheated human brain ribonucleoprotein is described. Chromatography of RSP on DEAE-cellulose permitted the isolation of an acid protein fraction (AP) containing brain-specific antigens identical with those from heated brain extracts. AP contained a minimum of three distinct antigenic components which emerged as a single peak on rechromatography, and were incompletely separable by immunoelectrophoresis or analytical ultracentrifugation. Pronase digestion liberated material with the general properties of a glycolipid; digestion products lost ability to precipitate with antiserum to the intact material. Neuraminidase treatment resulted in the appearance of at least one previously masked determinant, presumably related to oligosaccharide residues since the new determinant was destroyed by periodate treatment. Periodate did not affect ability of AP to form immunoprecipitin arcs unless AP was previously desialized. A chloroform-soluble fraction liberated during acid hydrolysis of AP has not been identified. The possible chemical nature and intracellular association of AP are discussed.