interleukin 2, human cell, T lymphocyte
It is known that the production of cytolytic T lymphocytes requires growth factors such as interleukins 2 and 4 (IL-2 and IL-4). Elsewhere we have described bioassays that detect a cytokine that operates in concert with growth factor to generate cytolytic T lymphocytes. The factor that is termed cytolytic T-lymphocyte differentiation factor (CDF), together with IL-2 and lectin, mediates the formation of CD8+ killer cells in 2 days from thymocyte or peripheral lymphoid precursors. CDF is not mimicked by natural or recombinant sources of interferons, colony-stimulating factors, and IL-1 to IL-4. Here we use these bioassays to isolate and further characterize a single 24-kDa CDF protein from the conditioned medium of stimulated human blood mononuclear cells. CDF is first enriched by three successive chromatographic procedures that utilize anion exchange, hydroxyapatite, and phenyl-Superose. A single 24-kDa band with CDF activity is then isolated on 12% NaDodSO4/PAGE and clearly distinguished from the 17-kDA band of IL-2. The apparent molecular mass is similar under reducing and nonreducing conditions. After elution from NaDodSO4/PAGE the cytokine is maximally active at 0.25 nM in the CDF assay and has no growth factor activity for T lymphoblasts. To generate cytolytic CD8+, CD4- cells from spleen and lymph node T lymphocytes, IL-2 and small numbers of accessory dendritic cells must be applied together with CDF.
Cernetti, C., R. M. Steinman, and A. Granelli-Piperno. 1988. "Identification of a 24-kDa Cytokine that is Required for Development of Cytolytic T Lymphocytes." Proceedings of the National Academy of Sciences of the United States of America 85 (5): 1605-1609