6025

Several different approaches have been used to expand and activate human umbilical cord blood (UCB) T cells ex vivo for infusion into patients with various cancers and infectious diseases. This study was designed to establish a more effective and safe culture system for the ex vivo expansion, maturation and activation of human UCB T cells by investigating the use of autologous or homologous cord blood plasma (ACBP, HCBP), instead of fetal bovine serum (FBS). We collected 36 UCB samples at the time of delivery from uncomplicated normal full-term pregnancies. Fresh umbilical mononuclear cells were isolated by Ficoll-Hypaque density centrifugation. The nonadherent mononuclear cell fractions of each of the 12 samples were cultured with anti-CD3 antibody, IL-2 and individually with ACBP, HCBP or FBS. On day 8, the cellular proliferation rate, cell surface markers and cytotoxicity were assessed. There was no significant difference in proliferation rate among each supplemented medium (P >0.05). The CD3+ was expressed on over 95% of the cells cultured in all three media, compared to the precultured cells. The CD4+/CD8+ ratio of expanded T cells in FBS-supplemented medium appeared to remain greater than one on day 8, but did not in ACBP or HCBP. In ACBP-contained medium, the expression of CD3+CD8+, CD3+CD25+ and CD3+CD45RO+ cells was significantly increased, whereas CD3+CD4+ decreased (P < 0.05). In HCBP-supplemented medium, the expression of CD3+CD8+, CD3+CD25+, CD3+CD45RA+ and CD3+CD45RO+ cells was significantly increased (P < 0.05). In FBS-contained medium, while the expression of CD3+CD4+, CD3+CD8+, CD3+CD25+, CD3+CD38+ and CD3+CD45RO+ cells was significantly increased (P < 0.05), CD3+CD45RA+ and CD16+CD56+ cells showed a decrease (P < 0.05). Compared to FBS, each of ACBP and HCBP-supplemented medium showed much lower expression of CD3+CD45RA+ and CD3+CD8+ cells (P < 0.05), but much higher expression regarding CD3+CD4+, CD3+CD25+, CD3+CD45RO+ and CD3+CD38+ cells (P < 0.05). There was no significant difference in cytotoxic potential to SK-OV-3 target cells at 10:1 and 4:1 ratio (P > 0.05) among three media, but a significant difference was shown in ACBP-supplemented medium at 40:1 ratio (P < 0.05). These data suggest that the ex vivo ACBP or HCBP combined with anti-CD3 and IL-2, significantly enhances proliferation, activation, maturation and cytotoxicity of UCB T cells as FBS, and supports the feasibility of ACBP and HCBP for future adoptive cellular immunotherapy, thereby indicating a breakthrough in the limitations of FBS. Moreover, the characteristic growth pattern caused by each supplementation may be used to selectively expand different functional T cell subsets, which could be useful in producing desired populations of T cells for adoptive immunotherapy applications. However, the clinical benefits and long-term consequences are to be examined further.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]