PURPOSE: To readily obtain the titled high-purity crystals useful as an anticancer agent, etc., by dissolving interleukin 2 in an aqueous solvent at a pH within a specific range, adding an inorganic salt to the resultant solution and depositing the aimed crystals.
CONSTITUTION: Interleukin 2 is dissolved in an aqueous solvent (preferably a solvent containing a polar solvent, e.g. lower alcohol, etc., added thereto) at 4.5W7.5pH, preferably 4.7W5.7pH and 6.3W7.3pH and an inorganic salt, preferably ammonium sulfate is added thereto to deposit and give the aimed crystals. The concentration of the interleukin 2 in the solution is preferably ≥3mg/ml and the concentration of the inorganic salt is preferably ≥1.0mol/l. For example, a phosphoric acid buffer solution, etc., is used for adjusting the pH.
MITSUI YUKIO
IITAKA YOICHI
NAGASHIMA SHINYA
KAWAKITA TETSUYA
FUKUHARA KENICHI
