Patent ID: 8921518

Claim:
A method for purifying interleukin 21 (IL-21) from one or more samples, wherein each sample comprises and at least one undesired impurity, the method for each sample comprising: (a) loading dissolved IL-21 onto a RPC-column, equilibrated with a solvent comprising water, 25-35 (w/w) % ethanol, 0.1-0.3 (w/w) % Tris, 0.5-1.0 (w/w) % KCl, pH 6-8, up to 20 g/l column material; (b) washing the column with up to 5 column volumes of the equilibrating solvent; (c) eluting IL-21 in a linear gradient of 0 to 100% of a eluting solvent comprising 50-70% (w/w) % ethanol, 0.1-0.3 (w/w) % Tris, 0.5-1.0 (w/w) % KCl, pH 6-8; (d) collecting the IL-21 containing fractions; (e) washing the column with up to 10 column volumes of the eluting solvent; and (f) regenerating the column with a 50-70% 1-propanol containing solution.