To demonstrate the effect of AB serum on terminal erythroid differentiation ex vivo.
 Methods: After separation of CD34+ cells from cord blood, the cells were cultured and divided into a control group and an experimental group. The effects of AB serum were examined by the expressions of different markers (GPA, Band3 and α4-integrin) for erythroblast differentiation and enucleation by flow cytometry. 
 Results: The CD34+ cells were successfully differentiated to enucleated red blood cells. There were evident differences among the expressions of GPA, Band3 and α4-integrin between the 2 groups. The percentage of GPA positive cells in the experimental group was bigger than that in the control group in every time point. The expression of Band3 in the experimental group was higher than that in the control group. The expression of α4-integrin in the experimental group was lower than that in the control group. In addition, the enucleation rate in the experimental group was higher than that in the control group.
 Conclusion: AB serum can promote the cell differentiation and enucleation during terminal erythroid differentiation in vitro.
ABO Blood-Group System ; blood ; physiology ; Anion Exchange Protein 1, Erythrocyte ; metabolism ; Antigens, CD34 ; blood ; Cell Differentiation ; genetics ; physiology ; Cell Nucleus ; Cells, Cultured ; Erythrocytes ; physiology ; ultrastructure ; Erythropoiesis ; genetics ; physiology ; Fetal Blood ; cytology ; physiology ; Flow Cytometry ; Glycophorins ; metabolism ; Humans ; Integrin alpha4beta1 ; metabolism