[39] Murine interleukin 2

Publisher Summary This chapter provides an overview of murine interleukin 2. Interleukin 2 (IL-2) is a glycoprotein secreted by subsets of T lymphocytes, and characterized by its ability to stimulate the proliferation of activated T lymphocytes. It regulates cellular immune responses, being produced by subsets of normal T lymphocytes carrying the characteristic markers of T helper lymphocytes, and at least partly replacing these cells in the generation of cytotoxic T lymphocyte (CTL) responses. The chapter emphasizes on the use of the MTL2 cell line and of methods for the assay of IL-2. The MTL2 line is of H-2 k origin and has a cytotoxic activity on cells of the H-2 d haplotype. It can be frozen in liquid nitrogen and recovered, an important consideration since cells may lose their sensitivity to IL-2 during continuous culture, probably by the generation and selection of IL-2- independent variants. DNA synthesis is assessed by the incorporation of either [ 3 H]TdR or [ 125 I]dIUrd into DNA. In addition, the total metabolic activity can be determined by the uptake and reduction of the tetrazolium dye 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT). This provides a convenient alternative to the uptake of radioactive precursors as a measure of IL-2. The chapter also explains gel filtration.