Abstract: Objective To isolate CD4⁺CD25⁺ regulatory T cells (Tregs) from human umbilical cord blood (UCB), and to amplify and culture in vitro CD4⁺CD25⁺ Tregs by immunomagnetic beads and report these function. Methods CD4⁺CD25⁺ Tregs were isolated from human UCB by immunomagnetic separation beads. The isolated CD4⁺CD25⁺ Tregs were co-cultured with expanded immunomagnetic beads. The content of lymphocyte in UBC was observed by lymphocyte analysis experiment, Tregs by magnetic beads sorting, and selected cell viability by PI staining. The proliferation ability of immunomagnetic beads to Tregs was observed under different culture conditions (immunomagnetic beads group, control group). Results CD4⁺CD25⁺Tregs and CD4⁺CD25^-cells in CD4⁺ UCB were about 4.5% and 95.5%, respectively. Tregs were effectively enriched by magnetic beads sorting and cells stained with PI showed no loss of cell viability, and the content was about 81%. After co-culture with human T cell amplified magnetic beads, Tregs could effectively amplify. Conclusion Immunomagnetic beads can effectively enrich Tregs in umbilical cord blood mononuclear cells without obvious damage. Experiments show that immunomagnetic beads can effectively amplify Tregs in vitro, while evaluation of cells biological function needs further research.

Key words: Regulatory T cells, Immunoamplified bead