The biochemical study of rat T-cell growth factor (interleukin 2)

Abstract T-cell growth factor (interleukin 2) was partially purified from the conditioned medium from Con A-stimulated rat splenocytes. It had the molecular weight of 23,000 according to gel filtration and in the range of 17,000–18,000 daltons according to PAGE in the presence of SDS. The molecular forms of IL 2 exhibited isoelectric points (pI) of 5.4–5.8 (major peak), 4.3–4.5 and 6.5–6.8 (minor peaks). T-cell growth-promoting activity was remarkably stable to temperature, pH, SDS and 2-ME treatments. Rat IL 2 did not bind to immobilized Con A, WGA, RC 1, and fucose-binding protein. The conditioned medium also contained the inhibitor of IL 2-dependent T-cell proliferation.