Abstract: A process for the production of ?-interferon comprising the steps: i) inducing of human leukocytes by means of a virus; ii) treating the leukocytes with an enhancing agent selected from: a) Xanthine, pyrimidinol and pyrimidinone or derivatives of anyone thereof, such as theophylline, 2-amino-5-bromo-6-methyl-4 pyriminidol or thymine; b) an organic solvent selected from the group consisting of non-aromatic ketones, aliphatic or cyclic amides, alkylated aliphatic or cyclic urea derivatives and aliphatic or cyclic sulfoxides, such as N-methyl-2-pyrrolidinone, acetone, 2-butanone, 1,3-dimethyl-2-imidazolidinone, dimethylsulfoxide, 4-methyl-2-pentanone-N-ethyl-2-pyrrolidinone, 2-pyrrolidinone, tetramethylene sulfoxide or N,N-dimethylacetamide; or a combination of the compounds from a) with an organic solvent from b).