Immunolocalization of Basic Fibroblast Growth Factor to the Microvascu-Lature of Human Brain Tumors

Abstract

A prominent feature of some tumors of the central nervous system is angiogenesis. In this process, basic fibroblastic growth factor (bFGF) plays a key role. Surgical specimens of 23 human brain tumors were examined, by immunocytochemistry with a highly purified murine monoclonal antibody to bFGF. Alternate sections were incubated with the Ki-67 monoclonal antibody to measure the growth fraction. Innumoreactivity to bFGF was observed in 20/23 (87%) of the neoplasms. All 18 malignant brain tumors, with elevated growth fractions, were immunoreactive as was a recurrent meningioma and an ependymoma. The three non-reactive tumors were benign, non-invasive, slow growing neomplasms, with a low index of proliferation, an acoustic schwannoma, a meningioma, and a cholesteatoma. Immunostaining to bFGF was found in the microvascular compartment in 18/23 (78%) of the tumors. Reactivity to bFGF was noted in the tumor cell nuclei in six (26%) and in the cytoplasm of two (9%) tumors. The immunostaing was not present after preabsortion of the antibody with pure human bFGF. In view of the role of bFGF in cell mitosis and invasion, the presence of bFGF predominantly within the tumor microvasculature indicates a cellular depot for a growth factor that mediates angiogenesis and tumorigenesis: bFGF provides a molecular target for adjuvant therapy of malignant CNS tumors by angiosuppression.