Background and Objectives
The incidence and severity of Graft Versus Host Disease following the use of umbilical cord blood as a source of stem cells for bone marrow reconstitution challenge the scientific findings of the immunocompetence of newborn immune cells. The reports show that self renewal characteristics and the proliferative capacity of primitive hematopoietic progenitors in the preterm cord blood are higher in comparison with term cord blood and bone marrow. In this study, the characteristics of preterm cord blood immune cells were analyzed from a naive point of view especially in comparison with its counterparts in term cord blood.
Materials and Methods
Term and pretem MNCs were isolated and cultivated in complete media containing PMA (50 ng/ml) and Ionomycine (1µg/ml) at the presence of monensin they were then permeabilized with %0.1 saponin. After cell stimulation with PMA and Ionomycine, staining was performed with Moab anti-CD69 antibody to estimate the level of activation and was also conjugated with anti- IL-10, IFN-γ, IL-4, IL-2 antibody to evaluate the production of cytokine. Mean percentage frequency of cytokine producing cells and the level of cytokine expression in CD4+/CD8+, CD45RA+/RO+ cells were analyzed by Epics-XL and IMMUNO-4 software. Statistical analysis was carried out using Kolmogrov-Smirnov and Student's t-test .
Cellular phenotypic analysis showed no significant differences in CD4 + CD45RA+, CD8+CD45RO+ and CD4+CD45RO+ cells in term and preterm cord blood (p< 0.05). Mean percentage of CD3+ , CD4+ , CD8+, HLA-DR+CD3+, DR - HLA+CD4+ and CD25+ cells had significant increment in term cord blood. No statistically significant differences in the level of expression and the frequency of cytokine producing cells were observed in distinct gestational ages.
Considering the lack of any significant functional differences between term and preterm cord blood immune cells, hematopoietic stem cells of preterm cord blood not only have the same immunological behavior, especially with respect to GVHD, but also have the higher frequency and proliferative capacity. The presence of immature progenitor cells may have priority to term cord blood and be applied in transplantation settings.
Key words:�Cord blood, CD4 positive T lymphocyte , CD8 positive T lymphocyte, Cytokine