Identification and characterization of a human T cell line-derived lymphokine with MAF-like activity distinct from interferon-gamma.
Culture supernatants of several human T cell leukemia cell lines were screened for macrophage-activating activity (MAF) as defined by induction of tumoricidal activity against human melanoma cells in a 72-hr assay. Two cell lines, MT-2 and C10/MJ2, were found to produce high levels of MAF activity constitutively, but the MT-2 cell line, unlike C10/MJ2, produced little IFN-gamma. This observation was confirmed by Northern blot analysis performed with specific IFN-gamma cDNA probe. The MT-2 cell line thus provides a useful system to evaluate the existence of lymphokines with MAF activity that are distinct from IFN-gamma. The MAF activity produced by MT-2 cells was distinguished from IFN-gamma by the following criteria. MAF activity was not removed by immunoaffinity chromatography with the use of immobilized specific polyclonal antibodies to IFN-gamma and was not neutralized by a monoclonal antibody to IFN-gamma. Heat or acid treatments of IFN-gamma resulted in loss of its antiviral activity, but these treatments had no effect on MAF activity. MAF activity was not abolished by polymyxin B sulfate, suggesting that this activity is not mediated by or dependent on LPS. Initial characterization studies performed by using membrane filtration, gel filtration chromatography, and isoelectric focusing indicate that the non-IFN-gamma MAF activity produced by MT-2 cells has an apparent m.w. of 55,000 and an isoelectric point of 5.5. Collectively, these data suggest that the MT-2 human T cell line constitutively produces high levels of MAF and low levels of IFN-gamma and offers a useful source for the further purification of a unique human lymphokine with macrophage-activating activity that is distinct from IFN-gamma.
D002460:Cell Line; D002472:Cell Transformation, Viral; D002474:Cell-Free System; D003470:Culture Media / Q000032:analysis; D003602:Cytotoxicity, Immunologic; D017977:Deltaretrovirus; D006801:Humans; D007371:Interferon-gamma / Q000502:physiology*; D007938:Leukemia / Q000276:immunology; D008222:Lymphokines / Q000032:analysis / Q000096:biosynthesis* / Q000502:physiology; D008262:Macrophage Activation; D016215:Macrophage-Activating Factors; D009000:Monocytes / Q000276:immunology; D013601:T-Lymphocytes / Q000378:metabolism*
D003470:Culture Media; D008222:Lymphokines; D016215:Macrophage-Activating Factors; D007371:Interferon-gamma