Process for the purification of prote? Nas binding il-18.

Use of an affinity ligand according to formula (I) wherein A1 and A2 are selected from the group consisting of an amine, ether and thioether of the structures: wherein R1 is selected from the group consisting of hydrogen, alkyl C1-C6 alkylaryl and C1-C6-aryl; B1 and B2 are independently selected from the group consisting of C1-C6 alkyl, C3-C8 cycloalkyl and aryl, wherein said B1 and B2 may be substituted with R2, OR2, SR2, or N (R2) 2; each R2 is independently selected from the group consisting of hydrogen, C1-C6alkyl, aryl and C1-C6 aryl; each X independently represents a nitrogen, a carbon carrying a hydrogen, a carbon carrying a chlorine group or a carbon carrying a cyano group; and Z is a functional group capable of reaction with a matrix selected from amine, azide and hydroxyl or is an amine-activated agarose that reacts directly with amine ligand; for the production of the binding protein IL-18 (IL-18BP) Purified