Patent ID: 7767714

Claim:
A method of enhancing an infectious disease-treating action of cystine or a derivative of cystine, which comprises administering, to a subject in need thereof, an effective amount of theanine or a salt thereof and cystine or a salt thereof or a derivative of cystine in combination, wherein said derivative of cystine is selected from the group consisting of glutathione, glutathione disulfide, a glutathione alkyl ester, an oxidized glutathione dialkyl ester, cysteine, a cysteine alkyl ester, 3-[(carboxymethyl)thio]alanine, an N-acylcysteine, an N-acylcysteine alkyl ester, an N-acylcystine, an N-acylcystine alkyl ester, an N,N′-diacylcystine, an N,N′-diacylcystine dialkyl ester, S-alkylcysteine sulfoxide, and salts thereof.