An additional CD28 costimulatory signal enhances proliferation and cytotoxicity of murine T cell-derived CIK cells.

OBJECTIVE: Cytokine induced killer (CIK) cells are ex-vivo expanded T cells endowed with both T and Natural Killer cell properties. The standard protocol for generation of CIK cells is to culture peripheral blood mononuclear cells (PBMC) in the presence of interferon-gamma (IFN-γ), monoclonal antibody (mAb) against CD3 and interleukin-2 (IL-2). However, this protocol lacks costimulatory signal (CD28), crucial for T cell activation. Herein, the proliferation and functional properties of murine thymocytes derived CIK cells generated with or without costimulatory activation provided by anti-CD28 mAb were examined.

METHOD: The proportion of CIK (Thy1.2+NK1.1+ and CD8+NK1.1+) cells in culture and the expression of cytotoxic granules (granzyme B and perforin) and proinflammatory cytokines (IFN-γ and tumor necrosis factor-alpha (TNF-α)) were determined by flow cytometry. Additionally, CIK cell cytotoxicity against YAC-1 murine lymphoma cells was measured by a propidium iodide-based assay.

RESULTS: The addition of anti-CD28 to standard CIK culture conditions increased the number of Thy1.2+ NK1.1+ and CD8+ NK1.1+ (the major effector population) cells by almost 40% and 32%, respectively. Furthermore, the cytotoxic potential of CIK cells cultured with the addition of anti-CD28 mAb was also enhanced, with a corresponding increase in CIK cells expressing granzyme B, perforin, IFN-γ and TNF-α.

CONCLUSIONS: The addition of anti-CD28 mAb generated more effective murine T cell-derived CIK cells.