Purify it by reverse phase HPLC. [Weir & Sparks Biochem J 245 85 1987, Robb et al. Proc Natl Acad Sci USA 81 6486 1984.] Interleukins (IL-1, IL-2 —lL18]. Interleukins are cytokines which cause a variety of effects including stimulation of cell growth and proliferation of specific cells, e.g. stem cells, mast cells, activated T cells, colony stimulating factors etc., as well as stimulating other ILs, prostaglandins release etc. They are small glycosylated proteins (ca 15 kD, 130-180 amino acids produced from longer precursors) and are sometimes referred to by other abbreviations, e.g. IL-2 as TCGF (T cell growth factor), IL-3 as multi-CSF (multilineage colony stimulating factor, also as BPA, HCSF, MCSF and PSF). They are produced in very small amounts and are commercially made by recombinant DNA techniques in bacteria or Sf21 insect cells. Interleukins for human (h-IL), mouse (m-IL) and rat (r-IL) are available, and up to IL-18 are available commercially in such purity that they can be used directly without further refinement, particularly those that have been obtained by recombinant DNA procedures which are specific. As well as the interleukins, a variety of antibodies for specific IL reactions are available for research or IL identification. [Symons et al. Lymphokines and Interferons, A Practical Approach, Clemens et al. Eds, p.272 1987, IRL Press, Oxford, ISBN 1852210354, 1852210362, Thomson et al. Eds, The Cytokine Handbook, 3rd Edn, 1998, Academic Press, San Diego, ISBN 0126896623.]
