Expression of oligodendroglia and schwann cell markers in human nervous system tumors : an immunomorphological study and western blot analysis

Sixty tumors of the central and peripheral nervous system and seven brain metastases of extracranial carcinomas were examined using the peroxidase-antiperoxidase method to study the expression of myelin basic protein (MBP), myelin-associated glycoprotein (MAG) and the HNK-1/Leu-7 epitope. The immunocytochemical findings were compared with and correlated to Western blot results. None of the tumor types, including oligodendrogliomas, neurinomas and neurofibromas, expressed MAG and MBP, whereas myelin sheaths and their remnants within the tumors yielded specific immunoreactions. In contrast, the HNK-1/Leu-7 antibodies labelled the majority of the tumors tested including oligodendrogliomas and Schwann cell tumors. As demonstrated by Western blot experiments the HNK-1/anti-Leu-7 antibodies exhibited positive reactions with diverse polypeptides both in tumors and in non-neoplastic brain tissue at positions not corresponding to MAG. This suggests that the epitope recognized by HNK-1/Leu-7 antibodies is shared by a variety of unrelated proteins in normal and neoplastic tissues. Our results strongly indicate the absence of detectable amounts of MBP and MAG in oligodendrogliomas and Schwann cell tumors. The immunomorphological and immunochemical findings clearly showed the wide distribution of the HNK-1 epitope within different tumor types of the central and peripheral nervous system. In conclusion, the data demonstrate that specific cell markers for human oligodendrogliomas and Schwann cell tumors are still lacking.