Modified immunoregulation associated with interferon-γ treatment of rat glioma

AbstractLittle is known about modulation by cytokines of major histocompatibility complex (MHC) antigen expression on intracranial tumors in vivo. The ability of cytokines to up-regulate MHC class-1 (MHC-1) antigen expression was investigated first in vitro using three rat glioma cell lines. Immunohistochemistry showed that incubation with recombinant rat interferonγ (rrIFNγ) increased MHC-1 antigen expression in RG2, C6, and 9L cell lines. Flow cytometric analysis revealed different baseline levels of MHC-1 antigen expression in each line (RG2 lowest, C6 highest), and that these levels increased in all lines after stimulation with 100 U ml–1 or more of rrlFNγ. The antitumor effect of rrIFNγ in vivo was evaluated by assessing survival of rats with implanted intracerebralRG2 gliomas after intracarotid infusion of rrIFNγ. A high dose of rrIFNγ (2.4×105 U kg–1) significantly increased the survival, compared to control (p<0.02). Intracarotid pre-treatment with the bradykinin analogue RMP-7 did not further inc...