Anti-normal brain antibodies were studied in glioma cyst fluids. Cyst fluids were obtained by stereotaxic puncture from 34 patients with cystic gliomas. Immunoglobulins were analyzed by immunohistochemistry, immuno-Western blotting, concentration measures, and isoelectrofocalization. 80% of cyst fluids stained astrocytes and/or microvessels in non-tumoral white matter. In white matter extracts, cyst fluids recognized five immunoreactive bands having apparent molecular masses of 50-75 kDa. Although cyst proteins could be of systemic origin, isoelectrofocalization analysis suggests an additional local immune response. These antibody activities could be involved in certain peritumoral events such as brain edema.