CD81 and hepatocellular carcinoma: One recent study used the monoclonal antibody AP33, a broadly neutralizing antibody against the CD81-binding site on HCV E2 (amino acid residues 412–423) [105–107], in conjunction with HCV-infected human hepatoma (Huh-7.5) and unadulterated NK cells to prevent E2/CD81 interactions and probe the significance of NK CD81/HCV E2 interactions in the context of NK cell inhibition.