[Preliminary study on the purification of IL-2]

Interleukin-2 (IL-2) which is produced by T-lymphocytes is a protein molecule with the molecular weight of 15,420-Daltons. It has good functions in curing a lot of diseases such as cancer and AIDS even with a small quantity. A new method for purification of IL-2 by preparative high performance liquid chromatography is described. It was the first time to use hydroxyapatite as the packing to separate IL-2. IL-2 has one disulphide bridge (between 58th Cys and 105th Cys) and one free cysteine. In order to prevent aggregation and formation of wrong disulphide bond, 50 mumol/L Cu2+ and 1.5 mol/L guanidine hydrochloride was used for autoxidation and denaturing. Then we used mainly two chromatographic steps: First, Sephadex G-25 Gel permeation chromatography was used to separate guanidine hydrochloride and small molecules. Second, large scale preparative HPLC was used to separate impure protein from IL-2. Gradient elution was performed with phosphate buffer (pH 6.8). Its purity was examined by SDS-PAGE. Its activity reached 1 x 10(6) U/mg by CTLL-2 cell MTT method. The results showed that it is a suitable method for the large-scale purification of IL-2.