Humoral and cellular immune responses: independent forces or collaborators in the fight against cancer?

Recent advances in our understanding of immune function with regard to the generation of a potent antitumor response have resulted in a renewed interest in cancer vaccines and point to a role for immunotherapy in the treatment of cancer. Currently, the majority of vaccine strategies for the treatment of solid malignancies focus on the generation of cytotoxic T lymphocytes (CTL) that destroy tumor cells that express a given target protein, or antigen. However, antibody therapies have already been successful against some cancers. Current humoral immunotherapy typically involves the passive infusion of monoclonal antibodies, which usually target a specific tumor-encoded antigen. However, vaccines can be engineered to induce humoral immunity. By focusing on the cellular arm of the immune response at the expense of humoral immunity (or the converse), we may have inadvertently limited the potential efficacy of our anticancer vaccines. This article seeks to explore the notion that a vaccine designed to optimally activate both arms of the immune system may well generate an antitumor immune response greater than the sum of the two individual effector mechanisms alone.