HCMV-infected human THP-1 cells induce expression of HLA-G and its receptors

AIM: To investigate the differential expression of human leukocyte antigen-G (HLA-G) isoforms and its receptors in human monocyte line THP-1 after human cytomegalovirus (HCMV) infection for exploring the role of HLA-G in HCMV escaping the immune response of the organism.METHODS: THP-1 cells were infected with HCMV Towne strain. The expression of HLA-G isoforms at mRNA and protein levels was determined by RT-PCR and Western blot, respectively. The surface expression of HLA-G and its receptors ILT2/ILT4 and the cell viability were analyzed by flow cytometry. The levels of soluble HLA-G (sHLA-G) and IL-10 were measured by ELISA.RESULTS: After infection of the THP-1 cells with HCMV, no obvious apoptosis in the cells was observed, and the viability of the cells was high. A significant up-regulation of HLA-G1, -G3, -G4 and -G5 at mRNA expression level 1 d after infection was found, while the protein expression of HLA-G1 and HLA-G5 isoforms was mainly detected. The expression of HLA-G/ILT2/ILT4 was evidently up-regulated 1 d after infection. The level of sHLA-G was significantly increased 1 d after infection as compared with control group (P<0.01). The expression of IL-10 was obviously up-regulated 1 d post-infection as compared with control group.CONCLUSION: The differential expression of HLA-G isoforms and secretion of the receptors ILT2/ILT4 and IL-10 in the THP-1 cells are induced after HCMV infection. This study provides experimental evidence for evaluating the immune mechanism of HCMV infection.