EXPRESSION OF TUMOR-NECROSIS-FACTOR-ALPHA, FACTOR-BETA AND INTERFERON-GAMMA GENES WITHIN HUMAN NEUROGLIAL TUMOR-CELLS AND BRAIN SPECIMENS

Expression of cytokine genes, TNF-α, TNF-β and IFN-γ, in human astroglial cell lines and in fresh brain specimens was studied by PCR. mRNA transcripts of TNF-α could be detected in three out of five astrocytomas and neuroblastoma cell lines, and after stimulation with IL-1β/IFN-γ or LPS/IFN-γ all these cell lines expressed TNF-α genes. TNF-β genes could not be detected in these cell lines. We were able to detect expression of IFN-γ genes within two astrocytoma cell lines, which interestingly did not show TNF-α activity. In addition to the cultured cells, we also examined gene expression of these cytokines within four human malignant astrocytoma specimens, two peritumoral brain and two autopsied normal brains. The results show that tumour and surrounding reactive lesions express TNF-α genes (four of six) but not normal brains. The concentration of these cytokines in the supernatant of cultured cells was measured quantitatively by TNF-α, -β or IFN-γ ELISA. The combined stimulation of these neuroglial cell lines with IL-1β and LPS or IFN-γ, revealed a high level of TNF-α activity. This was especially evident with a neuroblastoma cell line. The concentration of TNF-α in the supernatant of the IMR32 neuroblastoma cell line increased markedly upon stimulation with IL-1β in both a time- and dose-dependent fashion in the presence of LPS or IFN-γ. Next, we examined expression of IL-1β and IFN-γ genes in the brain specimens. The result shows that four in six tumour and peritumoral regions expressed IFN-γ genes and one specimen showed IL-β gene by PCR. From these experiments it is suspected that neuroglial cell-derived TNF-α induced by IL-1β of IFN-γ may participate in local immune reactions of the brain in an autocrine and paracrine fashion. © 1994.