巨细胞病毒抑制树突状细胞抗原递呈功能

目的： 探讨巨细胞病毒（CMV）对单核细胞来源的树突状细胞（DC）的感染效率及对受染细胞的功能影响。方法: 以50半数细胞培养感染量（TCID50）滴度的CMV与未成熟及成熟DC（imDC，mDC）共培养，逆转录－聚合酶链反应（RT-PCR）方法检测细胞内CMV即刻早期抗原（IEA）mRNA水平，间接免疫荧光技术检测受染细胞内早期抗原（EA）阳性率，流式细胞仪检测细胞胞内病毒晚期抗原pp65表达，BrdU ELISA法检测受染DCs（cmv-imDC,cmv-mDC）刺激异基因T细胞增殖能力。结果: 感染 12 h，cmv-mDC内IEA mRNA水平低于cmv-imDC，相对表达量分别为0.102±0.020和0.862±0.124（P<0.05）。24 h，imDC组EA阳性率高于mDC组，分别为(62.32±14.20)%和(10.78±3.04)%（P<0.01）。72 h，cmv-DC胞内低表达pp65抗原，imDC和mDC中阳性率分别为4.86%和0.82%。与未处理mDC相比，cmv-imDC经成熟诱导因子LPS作用后，其刺激异基因T细胞增殖能力较弱（均P<0.05）；而cmv-mDC，仅当DC/T细胞为 1∶1 时，刺激能力下降（P<0.05）。结论: CMV可有效感染imDC，并在细胞内复制活化；cmv-DC的抗原递呈能力下降。

Inhibitive effect of cytomegalovirus infection on immunological functions of dendritic cells

AIM: To investigate the effect of cytomegalovirus (CMV) infection on the immunological functions of dendritic cells (DC) derived from monocytes. METHODS: RT-PCR assay was used to detect the mRNA expression of CMV immediate early antigen (IEA) and glyceraldehyde phosphate dehydrogenase (GAPDH) genes in immature and mature dendritic cell (cmv-imDC, cmv-mDC) infected by 50-folds median tissue culture infective dose (TCID50) of CMV. The expression of early antigen (EA) in cmv-imDC and cmv-mDC was analyzed by indirect immunofluorescence assay. CMV late antigen pp65 was determined by flow cytometry. The allogeneic stimulating capacity of cmv-DC was assayed by mixed lymphocyte reaction (MLR) with BrdU incorporation. RESULTS: The expression of IE mRNA in cmv-mDC was lower than that in cmv-imDCs at 12 h after infection (0.102±0.020 and 0.862±0.124, respectively, P<0.05). EA, primarily localized in nucleus, was found in cmv-imDC (62.32±14.20)% and cmv-mDC (10.78±3.04)% at 24 h (P<0.01). pp65 positive cells in cmv-imDC and cmv-mDC at 72 h were 4.86% and 0.82%, respectively. Compared with untreated mDC, cmv-imDC showed depressed antigen presentation even after stimulated with maturation signal factor LPS (both P<0.05), while cmv-mDC had weaker stimulating capacity only when DC/T cell ratio was 1∶1 (P<0.05). CONCLUSION: CMV efficiently infectes and replicates in imDC. CMV suppresses the antigen presenting capacity of cmv-DC.