[Cytomegalovirus infection down-regulates the expressions of CD226 and CD16 in blood NK cells of the renal transplant recipient].

Objective: To investigate the effect of cytomegalovirus (CMV) infection after renal transplantation on the expressions of the activation receptors CD226 and sCD16 in natural killer (NK) cells.

Methods: Peripheral blood samples were obtained from these kidney transplant recipients with CMV infection, stable recipients, and normal healthy controls, and the expressions of CD3, CD56, CD16 and CD226 of all the samples were analyzed by flow cytometry.

Results: Compared with patients recovered from CMV infection, normal healthy controls and the stable recipients, the percentage of NK population in lymphocytes did not vary among these groups (P=0.18). However, the percentage of peripheral blood CD226⁺NK cells in NK population of the CMV infection group [(75.06 ± 13.65)%] was significantly lower than that of the healthy controls [(88.28 ± 11.98)%] and stable recipients [(87.53±6.43)%]. While the percentage was recovered during CMV infection recovery stage [(88.37±8.91)%], which was not different from that of normal healthy controls and the stable recipients. The mean fluorescence intensity (MFI) of CD226 was not significantly different among the health controls, stable recipients and CMV infection patients, while it was significantly higher in the patients recovered from CMV infection than in the above three groups. A decrease in the percentage of CD16(+)NK cells in NK population was observed in the group of CMV infection [(75.06 ± 13.65)%], which was significantly lower than that of the stable recipients [(88.28 ± 11.98)%] and health controls [(90.35 ± 10.07)%]. The CD16 expression on NK cells was elevated to (86.30 ± 14.01)% when the infection was controlled, which was not different from the stable recipients and healthy controls. The MFI of CD16MFI in NK cells was similar in all groups.

Conclusion: CMV infection down-regulates the expressions of CD226 and CD16 in NK cells of patients after kidney transplantation. When the infection was controlled, the expressions of CD226 and CD16 on NK cells were recovered. These results indicated that the membrane CD226 and CD16 molecules were involved in NK cell-mediated anti-CMV infection.