OBJECTIVETo evaluate the method for expanding Valpha24 natural killer T (NKT) cells with alpha-galactosylceramide (alpha-GalCer) ex vivo.

METHODSMononuclear 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.

RESULTSValpha24 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.

CONCLUSIONSAlpha-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.