The objectives of this study were, first to characterize the immunological differences of the T lymphocytes of umbilical cord blood (UCB) compared to those of adult; second to expand the T lymphocytes in ex vivo condition of a short term culture, and to assess the immunological function of the expanded T lymphocytes.

The immunophenotypic study of 40 UCB and 10 adult peripheral blood (PB) was performed. The fresh UCB mononuclear cells (MNCs) were isolated. The nonadherent MNC fractions were then cultured with the anti-CD3 antibody with or without Loranthus yadoriki (10 microgram/ml). The MNCs were cultured in the anti-CD3 antibody-coated flasks for 4 days, and then transferred to the non-coated flasks, which were added IL-2 175 U/ml and cultured for another 10 days. Proliferative ability of UCB T lymphocytes, cell surface markers, and cytotoxicity assays of the expanded T lymphocytes were performed.

Cell surface markers of the UCB T lymphocytes were different from those of adult T cells. The UCB T lymphocytes cultured with the anti-CD3 antibody 100 ng/ml showed a significant increase in the proliferative ability (p<0.05). After culture in the anti-CD3 antibody coated flask with IL-2, expression of the activated T lymphocytes were increased significantly. The cultured cells exhibited substantial killing activity on the SK-OV-3 target cells compared to the fresh UCB lymphocytes.

The ex vivo combination of the anti-CD3 antibody and IL-2 significantly enhanced proliferation, activation, and maturation of the UCB T lymphocytes. Moreover cytotoxic potential of expanded UCB T cells was observed.