Purification and characterization of guinea pig lymphotoxin produced by lymph node cells stimulated by phytohemagglutinin.

Guinea pig lymphotoxin (LT) produced by stimulation of lymph node cells with Phaseolus vulgaris phytohemagglutinin was purified approximately 1,000-fold in specific activity by ammonium sulfate fractionation, DEAE-Sephadex column chromatography, and gel filtration on Sephadex G-100. The properties of LT tested at the various stages of purification revealed that the LT was a heat-sensitive, protease-sensitive proteinaceous substance, and its approximate molecular weight was estimated to be 50,000 by means of gel filtration. The most purified fraction (Fr. D) was found to be devoid of the activities of migration inhibitory and mitogenic factors, clearly indicating that these activities are mediated by different substances.