Chromatographic separation from known cytokines of a helper factor necessary for the generation of murine cytolytic T lymphocytes

A helper factor (CHF) necessary for the generation of primary allospecific CTL using BALB/c (H-2(d)) responder spleen cell and x-irradiated RDM4 (H-2(k)) stimulator tumor cells was obtained from cultures of mouse spleen cells stimulated for the production of secondary anti-Sendai virus CTL and fractionated by gel filtration chromatography to obtain a 30,000 m.w. species (CHF30). DEAE-cellulose chromatography separated CHF activity from the majority of interleukin 1 (IL 1), interleukin 2 (IL 2), granulocyte-macrophage colony-stimulating factor (CSF), and interferon (IFN). Interleukin 3 (IL 3) and CHF co-eluted when this procedure was used. Reverse-phase high performance liquid chromatography (HPLC) of CHF30 with a variety of elution conditions allowed the separation of CHF activity from IL 1, IL 2, IL 3, CSF, and IFN. IL 3 and CSF in the CHF30 preparation were stable at 80°C for more than an hour, whereas CHF activity decreased rapidly during the first 10 min of incubation. Trypsin treatment of the same material showed that CHF activity was resistant to digestion for 40 min, whereas IL 3 and CSF lost most of their activities during the first 5 min of incubation. These results indicate that CHF activity is mediated by molecules biologically and biochemically distinct from the well characterized cytokines.