STUDIES ON ‘BRAIN‐SPECIFIC’ PROTEINS IN AQUEOUS EXTRACTS OF BRAIN TISSUE

STUDIES on the nature of brain proteins by chemical and electrophoretic methods have yielded information on the quantitative distribution of various components and on distinctive patterns of electrophoretic mobility, but no evidence of specificity with regard to brain tissue. Further progress in this direction became possible when chemical and immunological methods were combined. A species-, but not brain-specific protein from aqueous extracts of brain tissue, with rapid diffusion in agar gel, was described by Ross (1960). CLAUSEN and ROSENKAST (1962) differentiated proteins and mucopolysaccharides in aqueous extracts of brain tissue using special stains in electrophoresis. With antibrain serum DENCKER SVENNILSON and SWAHN (1963) found a protein fraction migrating in the a,-range in aqueous extracts of whole brain tissue. This fraction was absent from serum, normal cerebrospinal fluid (CSF) and plasma. Occasionally this fraction appeared in the CSF of patients with brain tumours. CASPARY and FIELD (1963) described a brain-specific protein destroyed by trypsin, pepsin, papain and ficin using the Ouchterlony method. In addition, these authors found two antigenic proteins common to brain, liver and kidney. One of these was resistant against proteolytic enzyme treatment. According to BRUNNGRABER and BROWN (1 964), protein-linked sialomucopolysaccharides are major constituents of rat brain subcellular fractions, with a relatively higher concentration in the microsomes. A strongly acidic, rapidly migrating, small-molecular protein was found in all parts of the nervous system of various species by MOORE and MCGREGOR (1965). An antiserum against this protein reacted specifically with a soluble protein prepared from the post-mitochondria1 fraction of grey substance (RUBM and STENZEL, 1965). Using anti-rat brain immune sera MACPHERSON (1965) found a brain-specific antigen in the water-soluble fraction of whole brain tissue migrating in the /?-area in immunoelectrophoresis. This component was present in guinea pig, rabbit, calf and human brain. With antisera against normal brain tissue, glioma tissue and CSF, HASS (1966) was also able to demonstrate an a,-component in human brain, liver, spleen and metastatic carcinoma cyst fluid, and in three specimens of CSF from patients with craniopharyngioma, intraspinal ependymoma and meningioma. Twenty-four specimens from patients with other tumours of the central nervous system were negative. In methodologically similar investigations we were also able to show that a protein fraction migrating in the 8-range, not present in plasma, serum and normal CSF, can be found regularly in aqueous extracts from brain, liver, kidney, pancreas, adrenal