Abstract: A chemically-defined, stable, protein-free medium has been devised which is capable of supporting the growth of lymphoid cells, particularly hybridomas, even in anchorage-independent cultures. Doubling rates are close to those obtained with serum-supplemented media. The medium preferably comprises a nonproteinaceous organo-iron compound, especially a nitroprusside salt, an iron chelator such as EDTA, and a selenium compound, such as selenium dioxide or sodium selenite.
Abstract: Cells grown in chemically defined (serum free) media are protected against endogenous oxidizing agents by a nontoxic antioxidant with free thiol groups, at cell densities less than about 10.sup.5 cells/ml, especially DL-penicillamine, N-acetylcysteine, mercaptoproprionic acid, 2-mercaptoethanesulfonic acid, and thiolactate. These agensts are useful in the maintenance and growth of hybridomas in such media.