Expansion of human Valpha24+ NKT cells by repeated stimulation with KRN7000.

Changes in Valpha24+Vbeta11+ NKT cell number and function are associated with human autoimmune diseases and cancer. Restoration of this corresponding NKT cell population in mice or in vivo activation with alpha-galactosylceramide (KRN7000) can prevent or reduce tumor growth and autoimmunity. Although the therapeutic value of these natural killer T (NKT) cells in man remains to be determined, large numbers of functional antigen-specific NKT cells can be expanded in vitro. We show that Valpha24+Vbeta11+ human NKT cells are expanded by repeated stimulation with KRN7000, unfractionated donor peripheral blood mononuclear cells (PBMC), and recombinant human interleukin-2 (rhIL-2). NKT cells were expanded continuously for more than 2 months with a potential yield of >10(12) cells. The expanded NKT cells retained their CD4+ or CD4- phenotype after restimulation and were functional as shown by cytokine secretion, killing of antigen-pulsed target cells, and activation of NK cell cytotoxicity. This expansion method may be useful for proof-of-concept studies involving adoptive transfer of ex vivo-expanded NKT cells as a new therapeutic option for cancer and autoimmune diseases.