Non-specificity of anti-carbonic anhydrase C antibody as a marker in human neurooncology

Because the presence of carbonic anhydrase C (CA C) has been demonstrated in the oligodendrocytes of the mouse, rat and man, anti-CA C serum has been considered to be a possible specific marker for these cells. In order to determine its value in human neurooncology, specimens from 110 human tumors from the central and peripheral nervous systems as well as from five cases of cerebral infarction and two of multiple sclerosis were tested immunohistochemically by the peroxidase-antiperoxidase method with anti-CA C serum. Reactive astrocytes, oligodendrocytes in the neural parenchyma surrounding tumors, and neurons included in areas of neoplasia showed CA C immunopositivity. In 92% of the astrocytomas and 56% of the glioblastomas variable numbers of tumor cells were positive. Some tumor cells positive for glial fibrillary acidic protein in ependymomas and astroblastomas were also CA C-positive. Schwannomas (86%), neurofibromas (100%) and meningiomas (86%) showed CA C positivity of the tumor cells, as did choroid plexus papillomas and gangliogliomas. However, all the medulloblastomas, neuroblastomas, central neurocytomas or melanomas tested in this study were entirely CA C-negative. In some examples of squamous cell carcinoma, leiomyoma, leiomyosarcoma and fibrous histiocytoma, CA C-positive neoplastic cells were also demonstrated. Our findings indicate that since various types of neoplastic and reactive cells express CA C positivity, the anti-CA C serum cannot be used as a specific marker for any tumor in human neurooncology.