Effects of human fibroblast interferon on human gliomas transplanted into nude mice.

Daily intratumor injection of human fibroblast interferon (HuIFN-beta) resulted in significant growth inhibition of human gliomas transplanted into nude mice. Light and electron microscope examinations were conducted to estimate the efficacy of HuIFN-beta. A 29-day daily treatment with HuIFN-beta induced complete regression of oligodendroglioma KG-1--a slowly growing tumor line positive for S-100 protein and negative for glial fibrillary acidic protein (GFAP)--in 9 out of 10 mice receiving 6 X 10(5) IU and 6 out of 9 given 1 X 10(5) IU. In mice with glioblastoma multiforme TMIMS-583, which showed more rapid growth and was positive for GFAP, dose-dependent growth inhibition was observed during 23 days of HuIFN-beta administration. Pathological changes of TMIMS-583 induced by HuIFN-beta were characterized by a decrease of the metaphase tumor cells, by enhanced degeneration of tumor cells with stromal reaction and round cell infiltrates, and by prominence of multinuclear giant cells containing glial filaments. Tumor weights were well correlated with the number of tumor cells in the metaphase (r = 0.89).