Expansion and function of MHC restricted killer T cells derived from umbilical cord blood

Abstract

This study was to expand the cytotoxic T lymphocytes (CTL) through inducing the differentiation of umbilical blood monomuclear cells (UBMNC) by using various combination of cytokines, and to investigate the functions of expanded CTL. The MNC were isolated by ficoll density gradient centrifugation. Then, the PHA-P, IFN-γ combined with IL-2, IL-15 and other cytokines were used for induction and expansion of the cord blood-derived CTL. The biological function of CTL was examined by phenotype analysis, cytotoxic tests and real-time fluorescence quantitative PCR. After expansion for 15 days, the cell number increased by 1522% ± 137%. The content of CD3(-)CD8(-) cells in uncultured cord blood MNC was 95%, and the CD3(+)CD8(+) CTL cells reached 82.77% in cultured cord blood MNC after expansion for 15 days. The expanded CTL cell showed the cytotoxic activity against K562 and HeLa cell line. The killing rate of MNC was 61.88 ± 1.08%. After expansion, the killing rate could reach to 90% with the average value of 90.33 ± 2.02%. The expanded CTL cells highly expressed some key cytokines, such as granzyme A, granzyme B, GM-CSF, granulysin, IFN-γ, TGF-β, TNF-α and perforin. Compared with the control group, the expression of IFN-γ and TGF-β significantly increased (P < 0.05), and the other factors dramatically increased (P < 0.01). The cord blood-derived CTL can be expanded by different combinations of cytokines. These protocols may provide alternative choices for CTL cell expansion in tumor adoptive immunotherapy.