Cord blood hematopoietic progenitor cell concentration and infant sex

BACKGROUND: Characterization of cord blood facilitates understanding of the factors affecting cord blood transplant quality and improvement of transplantation results. Cord blood obtained from male and female infants has not been thoroughly characterized. STUDY DESIGN AND METHODS: A study was performed to test the hypothesis that the cord blood hematopoietic progenitor cell content-of which the CD34+ cell and colony-forming unit (CFU) concentrations were taken as markers-would not only associate with birth weight but also with sex. The hematopoietic progenitor cell concentrations of 1999 healthy infants (47% female) were analyzed in a cord blood bank setting. RESULTS: Male infants had significantly higher median CD34+ cell concentrations than female infants (31.8/mu L vs. 30.2/mu L, respectively; p = 0.03). Although the disparity in absolute concentrations was small, it was 5.3 percent. In CFU subgroup analysis, the median CFU-mixed concentration of male infants (11.1/mu L) was higher than in female infants (9.9/mu L; p = 0.03). The difference was more pronounced when cumulative frequencies of the CFU-mixed concentrations from cesarean section deliveries were compared. In multivariate linear regression analysis, the positive influence of male sex on the CD34+ cell concentration was significant (p < 0.05). The expected higher median nucleated cell concentration of female compared to male infants (13.9 x 10(9)/L vs. 13.3 x 10(9)/L, respectively; p = 0.0001) was mainly due to the higher neutrophil concentration of female infants (7.1 x 10(9)/L vs. 6.5 x 10(9)/L, respectively, p < 0.0001). CONCLUSION: Cord blood hematopoietic progenitor cell concentration was higher in male infants, even after correcting for birth weight. Sex may affect the hematopoietic potential of cord blood transplants.