The immunocytochemical localization of GFA protein in experimental murine CNS tumors.

Immunocytochemical localization of GFA protein in formalin-fixed, paraffin-embedded tissue sections by the peroxidase-antiperoxidase method of Sternberger was used to study experimental murine CNS tumors. Transplacental tumor induction in rats by ethylnitrosourea produced oligodendrogliomas and mixed gliomas in the cerebrum and spinal cord, and malignant Schwannomas of the trigeminal nerve. A methylcholanthrene-induced mouse "ependymoblastoma" inoculated intracerebrally in normal and in toxoplasma-infected mice was also studied. A positive reaction of GFA protein antibody was seen in the astrocytic portion of the mixed gliomas; the oligodendrogliomas, the malignant Schwannomas and the mouse "ependymoblastoma" were negative. Staining for GFA protein delineated the astrocytic reaction of neural tissue adjacent to the tumors. The reaction was markedly intensified in the brains of mice infected with toxoplasma. Additionally, ependymal cells near the tumors stained positively for GFA protein; normal ependyma at a distance from tumor remained negative. The technique, which combines a high degree of specificity with great sensitivity and is readily adaptable to routinely processed tissue, should prove a valuable tool in experimental oncology of the central nervous system.