Suppression of graft-versus-host disease after adoptive infusion of alloreactive NK cells induced by silencing Ly49C gene in mice

To investigate suppression of graft-versus-host disease (GVHD) after adoptive infusion of alloreactive natural killer (NK) cells induced by silencing Ly49C gene.Silencing efficiency was detected by quantitative real-time reverse transcriptase polymerase chain reaction and flow cytometric analysis. The recipient mice were randomly divided into three groups which were respectively treated with RNAi Ly49C alloreactive NK cells, NK cells alone and RPMI 1640 culture medium. The cumulative GVHD scores, pathological lesion of liver, spleen, gut and survival time in the recipients were observed.The valid one of four siRNA duplex we designed selectively suppressed Ly49C mRNA expression by 63% (Max 70%) when compared to control levels, while flow cytometric analysis indicated Ly49C protein expression on NK cells transfected with Ly49C-124 siRNA was significantly decreased in comparison with that of negative control or mock (P<0.05). The scores of GVHD in RNAi-Ly49C NK cells group, NK cells alone group and blank control group were (1.30+/-1.34), (3.10+/-2.33) and (5.70+/-1.77) during 30 days after transplantation, respectively. Pathologic manifestations of liver, spleen and gut in RNAi Ly49C alloreactive NK cells group were slighter to a certain extent than those in other two groups. Survival time(days) of simply irradiation group, RNAi Ly49C NK cells group, NK cells alone group and blank group were (8.70+/-1.49), (63.00+/-24.81), (36.00+/-17.38) and (24.40+/-7.44), respectively.Infusion adoptively of alloreactive NK cells induced by silencing Ly49C gene could reduce GVHD degree and prolong survival time in GVHD mice model.