Peripheral blood T cell immuno-tolerance in PBSCT donors induced by rhG-CSF in vivo

The study was aimed to investigate the mechanism of T cell tolerance in human peripheral blood induced by rhG-CSF in vivo. Dendritic cell (DC) subsets, CD8(+)CD28(-) T suppressor cells and the expression of CD28 on T cells of peripheral blood before and after mobilization were analyzed by multicolor flow cytometry. The results showed that after mobilization by rhG-CSF in vivo, the relative counts of CD3(+)CD28(+) cells increased significantly (P < 0.01), and so did the CD8(+)CD28(+) cells (P < 0.01). The mean fluorescence intensity of CD28 expression on CD3(+) cells decreased greatly (P < 0.05), but there were no significant changes of the relative fluorescence intensity of CD28 overall expression on T cells (P > 0.05). The percentages of DC2 before mobilization were significantly lower as compared with normal bone marrow (P < 0.01). After using rhG-CSF, the DC2 count was significantly higher in the apheresis graft than in peripheral blood and bone marrow before mobilization (P < 0.01), while the DC1:DC2 ratios were lower (P < 0.01) and there was no significant difference of DC1 before and after mobilization (P > 0.05). The percentages of CD8(+)CD28(-) T suppressor cells increased significantly also after mobilization (P < 0.05). It is concluded that the higher numbers of DC2 and CD8(+)CD28(-) T suppressor cells in peripheral blood grafts may contribute to the ability of tolerance in peripheral blood T cells induced by rhG-CSF in vivo.PubMed0116-91