Mouse gamma interferon (IFN-gamma) was produced from a cloned T-cell lymphoma, L12-R4, stimulated with phorbol myristic acetate (PMA) at a concentration of 2 X 10(-7) M/ml. Absorption of crude IFN-gamma on silicic acid resulted in a 100-fold concentration and 10-fold purification. After application of this IFN-gamma to a Sephacryl S-200 column, 100% of the IFN activity was recovered in fractions containing molecular weights of 40 kD. When this material was applied to a Con A-Sepharose column, IFN activity was completely eluted with a linear gradient of alpha-methyl-mannoside. The specific activity of the recovered IFN-gamma was about 3.6 X 10(6) mg/ml of protein with 11,390-fold purification. Further investigations with Phenyl-Sepharose CL-4B and Chromatofocusing revealed that L12-R4 IFN-gamma is highly hydrophobic and has a pI around 5.4. Thus, by different types of chromatography procedures, L12-R4 IFN-gamma was found to be highly homogeneous with physicochemical properties similar to those produced by normal T-lymphocytes.

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The characteristics of the responder and stimulating cells involved in migration inhibition factor (MIF) production in primary ‘one-way’ mouse mixed lymphocyte reactions (MLR) were analyzed by using an indirect agarose droplet assay. T-lymphocytes are mainly responsible for MIF release, as shown by pretreatment with anti-Thy 1.2 serum plus complement or purification over a nylon wool column. On the other hand, macrophages and B-lymphocytes appear to be optimal stimulating cells. T-lymphocytes as stimulating cells induce MIF release, but to a much lesser degree than macrophages and B-lymphocytes. The kinetics of MIF production in MLR is related to the kind of stimulating cells employed. Lastly, the ability to release MIF is already present in the spleens of 1- to 2-week-old mice, lasts until 20 weeks of age and declines to undetectable levels at 50 weeks of age.