Growth promoting effect of recombinant interleukin I and tumor necrosis factor for human astrocytoma cells

Human IL I has been demonstrated to stimulate the growth of rat astrocytes in vitro. To determine if IL I has a similar growth promoting effect upon human brain cells, two astrocytoma cell lines were tested for their ability to incorporate 3H-thymidine in response to various types of IL I and tumor necrosis factor (TNF). The U373 astrocytoma was found to respond mitogenically to human native IL I, human recombinant IL I, rat IL I and murine recombinant IL I. The cell line failed to respond to recombinant IL 2 and recombinant α and γ interferon. The sensitivity of the U373 cells paralleled the murine thymocyte assay for IL I. Interestingly, the U373 responded mitogenically to recombinant TNF prepared by two different companies, thus indicating that TNF stimulates proliferation of this cell line and does not lead to cell death. In the murine thymocyte assay for IL I, TNF was not active. The results indicate that 1) both IL I and TNF are mitogenic for a human astrocytoma cell line and 2) the U373 cells may be used to assay both IL I and TNF in a highly sensitive mitogenic assay