Maternal obesity associated with increase in natural killer T cells and CD8+regulatory T cells in cord blood units

BACKGROUND: One of the major limitations of umbilical cord blood (UCB) as hematopoietic stem cell source is its restricted cell number. In mothers who are candidates for stem cell donation, there are variables that affect the quantity and quality of UCB units. The aim of this study was to determine if obstetric, maternal, and fetal factors modify the number of lymphocyte subsets in UCB units. STUDY DESIGN AND METHODS: This was a prospective, observational study. In UCB units, the numbers of CD34, NK, NKT, iNKT, Type 1 dendritic cells (DCs), Type 2 DCs, T gamma delta, T CD4+, T CD8+ lymphocytes, CD4+CD25+FoxP3+, and CD8+CD25+FoxP3+ T regulatory (Treg) cells were quantified by flow cytometry. RESULTS: Fifty-four UCB units were included; the donors' mean weight was 75 kg (range, 52 to 102 kg) and they had a mean body mass index (BMI) of 30 kg/m(2) (range 22 to 40 kg/m(2)), of which 12 (22%) had a normal BMI, 14 (26%) were overweight, and 28 (52%) were obese. The mean number of CD34+ cells was 4.45 x 10(6) (range, 0.7 x 10(6) to 20.5 x 10(6)). The number of NKT, CD3+, CD4+, CD8+, and CD8+CD25+FoxP3+ Treg cells was significantly higher in overweight or obese mothers; CD34+ cells were decreased in the same group. The number of iNKT and CD34+ cells was decreased in newborns weighing above the average. CONCLUSIONS: Maternal factors such as BMI, and fetal factors such as weight at birth, should be added to the selection criteria of UCB donors.