Immunophenotypes and Proliferative Function of Lymphocytes in Umbilical Cord Blood

Yang, Yoon Sun; Kim, Dae Won

Abstract

BACKGROUND: The umbilical cord blood (UCB) is highlighted to be a alternative source of hematopoietic stem cells with a hope of resolving major problems of bone marrow transplantation, which are the lack of suitable HLA-matched donors and the occurrence of graft-versus-host disease (GVHD). In this study we have assessed the immunological potential of lymphocytes in UCB, which could mediate GVDH, by immunophenotypes and functional assays on 20 UCB and 19 adult peripheral blood as controls.
METHODS
Immunophenotyping of lymphocytes were performed by one and two color flow cytometry (FACSort, Becton Dickinson, USA) using monoclonal antibodies (CD3, CD4, CD8, CD19, CD16/56, CD45RA, CD45RO, HLA-DR, HLA-DQ, HLA-DP, TCRalphabeta, TCRgammadelta). To assess proliferative responses, UCB lymphocytes were cultured in the presence of phytohemagglutinin (PHA) (5, 20, 100 ug/mL) and concanavalin A (ConA) (1, 5, 10 ug/mL). After 72 hour culture and 3H-thymidine pulsing, specific 3H-thymidine uptake was compared to control cells (without mitogen) by stimulation index (SI).
RESULTS
In phenotypic analyses, the percentages of CD4, CD8, CD45RO, TCRgammadelta and HLA- DP positive cells were significantly lower in UCB compared with the adult controls, while the percentage of CD45RA positive cells was increased in UCB. In addition, the percentages of B cell (CD19), NK cell (CD16/56), HLA-DR, HLA-DQ and TCRalphabeta were comparable to those in adult controls. In mitogen stimulated culture, UCB lymphocytes showed a significant lower proliferative responses at 20, 100 ug/mL of PHA, and 5, 10 ug/mL of ConA concentrations.
CONCLUSIONS
We have observed that UCB lymphocytes appeared to be phenotypically and functionally immature. Thus, UCB might be a attractive source for hematopoietic stem cells in that these UCB cells may have lower immunological potentials mediating GVHD after transplantation.