Study on the expression of CD28 costimulatory molecule on human lymphocytes inhibited by special siRNA

Objective:To investigate the expression of CD28 costimulatory molecule on human lymphocytes inhibited by siRNA.Methods:Three different siRNA (siRNA 1,siRNA 2,siRNA 3) were designed and synthysized and transfected into freshly isolated human lymphocytes with cationic liposome.At 24,48 and 72 h post transfection,the changes of CD28 expression were detected by flow cytometry,and the changes of CD28 mRNA levels were determined by semi quantitative RT PCR.Results:Different siRNA showed different reduction in CD28 expression.At 48 h post transfection,the degrees of reduction with siRNA 1,siRNA 2 and siRNA 3 were 22 10%±1 63%,73 50%±1 02% and 42 90%±0 89% respectively compared with the control ( P 0 001).siRNA 2 was the most efficient.The results of semi quantitative RT PCR assay indicated CD28 mRNA levels were inhibited after transfection.At least 4 fold of reduction in siRNA 2 group occurred at 48 h post transfection compared with the control ( P 0 001).Conclusion:Three different siRNA could reduce the expression of CD28 and the CD28 mRNA level.The silencing effect on CD28 mRNA induced by siRNA may contribute to costimulatory blockade.siRNA may be useful for further study on graft versus host disease (GVHD) after allogeneic bone marrow transplantation. [