Cytokine-induced killer cells: A novel immunotherapy strategy for leukemia.

Cytokine-induced killer (CIK) cells are NK-like T cells derived from peripheral blood mononuclear cells that are co-stimulated and expanded using cytokines for 14-21 days in vitro. CIK cells are a heterogeneous subset of highly-efficient cytotoxic T effector cells that mediate major histocompatibility complex-unrestricted cytotoxicity against a broad array of tumor cells. These effector cells are generated from patients with leukemia or healthy donors who demonstrate similar cytotoxic activity against leukemia blasts. Allogeneic CIK cells retain the ability to produce the graft versus tumor response and generate minimal graft versus host disease. In addition, CIK cells possess no cytotoxicity against normal hematopoietic stem cells in vivo. Leukemia recurrence remains a formidable obstacle, but adoptive immunotherapy offers promise for the eradication of minimal residual disease and prevention of leukemia relapse following hematopoietic stem cell transplantation. CIK cell infusion started a novel generation of adoptive immunotherapy and exhibits particular potential applications in the area of hematological malignancy. In the present study, the previous strategies of leukemia immunotherapy using CIK cells are reviewed and the future direction of development are discussed.