Expansion of Vα24+Vβ11+ NKT cells from cord blood mononuclear cells using IL-15, IL-7 and Ft3-L depends on monocytes

Abstract

Human Vα24+Vβ11+ NKT cells are a unique T cell population specifically and potently activated by α-galactosylceramide (αGalCer; KRN7000) presented by CD1d. Here, we present a simple and efficient method for expanding Vα24+Vβ11+ NKT cells from human cord blood mononuclear cells (CBMNC) using αGalCer in the presence of interleukin (IL)-15, IL-7 and Flt3-L. The addition of αGalCer from day 0, compared to its addition from day 8 or day 15, induced a greater expansion of NKT cells. The maximal expansion of NKT cells was observed after 15 days (2300-fold). Thereafter, the number of NKT cells decreased slowly, a decrease that was correlated with the diminution of CD1d-positive cells. NKT cell proliferation induced by αGalCer was not observed when CD1d-expressing monocytes were depleted from CBMNC, whereas B cell and dendritic cell depletions had no effect. Expanded NKT cells were CD4+CD8- and secreted both IL-4 and IFN-γ. In this system, CD3+ T cells and CD3-CD56+ NK cells were also expanded. However, the expansion of NKT cells had no significant functional effect on T and NK cells. This expansion method of CBMNC-derived NKT cells is simple and may be helpful for clinical use. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.