Objective: To evaluate the method for expanding Valpha24 natural killer T (NKT) cells with alpha-galactosylceramide (alpha-GalCer) ex vivo.
Methods: Mononuclear cells (MNCs) isolated from adult peripheral blood or umbilical cord blood (UCB) were divided into three groups. In Group A1 (n = 5), CD34+ progenitorderived dendritic cells were differentiated in a cytokine-supplemented culture system from cord blood and acted as antigen presenting cells (APC) to induce the expansion of cord blood Valpha24 NKT cells in presence of alpha-GalCer; in Group A2 (n = 5), adult peripheral monocyte-derived dendritic cells (Mo-DC) were used as APC to induce the expansion of adult peripheral NKT cells in presence of alpha-GalCer; whereas in Group B (n = 16), alpha-GalCer was added into adult peripheral MNCs culture system without additional DCs. Cytokine-produce were measured by ELISA, and NKT cells' proliferation ability, cytotoxicity, and suppressive effect on mixed lymphocyte reaction (MLR) were examined by MTT assays.
Results: Valpha24 NKT cells in Group A1, A2, and B were expanded up to 128 (95-207), 250.5 (179.6-790.6), and 326 (101-2 136) -fold by day 12, respectively. Adult NKT cells expanded in Group B were markedly better than those in Group A1 (P = 0.038). When stimulating by PMA, the NKT cells had a 3-day stimulate index of 1.80 +/- 0.41; and the secretion ratio of IL-4 to IFN-gamma of UCB or adult peripheral blood NKT cells were 0.30 +/- 0.13 and 0.28 +/- 0.18; and the ex vivo antitumor effect of expanded NKT cells were found in cell line HL60, KG1a, and Raji except for K562; and the suppressive effect of expanded NKT cells or the culture supernatant on MLR were confirmed.
Conclusions: Alpha-GalCer can facilitate the rapid shorttime expansion of Valpha24 NKT cells in presence of IL-2 and IL-15. These expanded NKT cells, kill tumor cell lines, and inhibit can massively excret IL-4 and IFN-gamma allogeneic T-cell response.