Substantially pure cytotoxicity triggering factor

A substantially pure human proteinaceous lymphokine having an apparent Mr of about 14 kilodaltons as determined by gel exclusion chromatography, using a gel matrix capable of fractionating proteins of an apparent relative molecular mass of about 6 to about 150 kilodaltons, having a specific activity of at least 50,000 units per milligram protein, that is capable of inducing the secretion of a tumor cell-killing factor that includes tumor necrosis factor-alpha from interferon-gamma-primed monocytes, said lymphokine being substantially free of pyrogen as well as interferon-gamma, interleukin-2 and direct cytotoxin.

A method of inducing peripheral blood mononuclear cells to secrete a tumor cell-killing factor that includes tumor necrosis factor-alpha comprising admixing primed effector cells in an aqueous medium with substantially pure CTF present in an amount effective to trigger secretion of a tumor cell-killing factor that includes tumor necrosis factor-alpha, said substantially pure CTF (a) being a human proteinaceous lymphokine having an apparent Mr of about 55 kilodaltons as determined by gel exclusion chromatography, using a gel matrix capable of fractionating proteins of an apparent relative molecular mass of about 6 to about 150 kilodaltons, (b) having a cytotoxicity triggering specific activity of at least 50,000 units per milligram protein, (c) being secreted in impure form from differentiated, stimulated normal human helper T cells that express a T3.sup.+ T4.sup.+ T8.sup.- M1.sup.- phenotype, (d) being capable of inducing the secretion of a tumor cell-killing factor that includes tumor necrosis factor-alpha from monocytes primed in culture for a time period of at least 36 hours with interferon-gamma, and (e) being substantially free of pyrogen as well as interferon-gamma, interleukin-2 and direct cytotoxin.

A method of inducing primed human effector cells to mediate the killing of tumor cells comprising admixing interferon-gamma primed human effector cells in an aqueous medium with an amount of a substantially pure human proteinaceous lymphokine effective to trigger secretion of a tumor cell-killing factor that includes tumor necrosis factor-alpha from said primed cells, and contacting tumor cells to be killed with the secreted tumor-killing factor, said substantially pure lymphokine (a) having an apparent Mr of about 55 kilodaltons as determined by gel exclusion chromatography using a gel matrix capable of fractionating proteins of an apparent relative molecular mass of about 6 to about 150 kilodaltons, (b) having a cytotoxicity triggering specific activity of at least 50,000 units per milligram protein, (c) being substantially free of pyrogen as well as interferon-gamma, interleukin-2 and direct cytotoxin, (d) present in impure form in a secretion from differentiated, stimulated normal human helper T cells that express a T3.sup.+ T4.sup.+ T8.sup.- M1.sup.- phenotype, and (e) capable of inducing secretion of a tumor cell-killing factor that includes tumor necrosis factor-alpha from monocytes primed in culture for a time period of at least 36 hours with interferon-gamma.