<；P>；PROBLEM TO BE SOLVED: To provide an effective technique concerning prevention of relapse of hepatitis C virus (HCV) infection after liver transplantation. <；P>；SOLUTION: The present invention provides a composition containing an anti-CD 81 antibody and an NK cell derived from liver in order to prevent relapse of HCV infection or a composition containing an NK cell subjected to activation treatment by using IL-2, etc., which is an NK cell-activating agent or a combination of the treated NK cell with the anti-CD 81, and further, a composition obtained by pretreating the therapeutic agent or prophylactic agent in the present invention with an anti-CD3 antibody. <；P>；COPYRIGHT: (C)2008,JPO&INPIT
