ABSTRACT
Objective:To investigate the role of mTOR in regulation of ICOS expression in human blood regulatory T cells. Methods:Isolation of Treg cells from human PBMC using MACS beads. We detected the ICOS expression on purified Treg cells and Treg cells viability using flow cytometry in anti-CD3 plus anti-CD28 ( antibody or beads) or anti-CD3 plus ICOSL-Fc for 3 days and 7 days. CFSE labeling human PBMC cells and in vitro cultured Treg mixed, Treg contact inhibition activity was detected by flow analysis. Results:After in vitro stimulation of Treg cells in the presence of anti-CD3+anti-CD28 for 3 days, there was no significant statistic difference in viability between ICOS+(92. 00±2. 69)% and ICOS-(90. 30±3. 53)% Treg-cells. After cultured for 7 days,the decreased ICOS+ Treg cells percentage within total Treg cells from ( 40. 20 ± 1. 83 )% to ( 11. 60 ± 1. 10 )% compared with that of 3 days. Further more,the ICOS expression level between stimulated with anti-CD28 or ICOSL-Fc condition group,compared with the ICOS MFI in the condition of anti-CD3 plus anti-CD28 treatment for 3 days was (2410. 0±746. 4) obviously higher than (403. 30±74. 42), that of the group treated with anti-CD3 plus ICOSL-FC. Rapamycin could partially suppress Treg cells ICOS expression,but unaffected the Treg suppression ability. Conclusion:ICOS expression level may not important for in vitro cultured human PBMC Treg cells survival although mTOR signling is important for regulation ICOS expression on in-vitro cultured Treg cells,but the ICOS expression on Treg regulated by multiply signaling pathways. CD28 signaling is the key stimulation factor for ICOS upregulation on in-vitro cultured Treg cells compared to ICOSL signaling.