传染性非典型肺炎病人外周血白细胞损伤的病理学研究

Pathologic study of circulating blood leukocytes in severe acute respiratory syndrome

目的 研究传染性非典型肺炎严重急性呼吸综合征 (SARS)病人外周血中白细胞的病理变化 ,及与SARS冠状病毒感染的关系 ,为探讨免疫细胞损伤在SARS发病机制中的作用提供形态学的依据。方法 采用 2 2例初步诊断的SARS病人外周血标本 ,及 4例正常成人外周血标本 ,分离收集所有的白细胞 ,进行透射电镜、免疫电镜和RT PCR检查。结果 白细胞的数量及亚型比例改变 :每个病例观察 10 0个细胞 ,分别计数粒细胞、淋巴细胞和单核细胞的数目。与正常组对照 ,粒细胞数目增多 (P <0 .0 5 ) ,淋巴细胞明显减少 (P <0 .0 5 ) ,T淋巴细胞 (CD4 5RO阳性 )仅占残存白细胞总数的 6 %～ 7%。在外周血白细胞胞浆内发现冠状病毒样颗粒者 6例 ,与RT PCR阳性者重合比例为5∶6。分别计数在各类白细胞中可观察到冠状病毒样颗粒的阳性细胞数 ,发现淋巴细胞中可观察到病毒的阳性细胞数最高。SARS病人血白细胞中的冠状病毒样颗粒为圆形 ,或略呈卵圆形 ,80～ 12 0nm左右 ,致密的双层质膜包绕 ,核心较疏松 ,膜外有放射状排列的纤细突起。散在分布于胞浆或粗面内质网、高尔基器及膜包绕的空泡中。淋巴细胞有变性和活化增殖的现象。结论 在SARS病人的血白细胞 ,内观察到冠状病毒样颗粒。提示 ,血细胞特别是淋巴细胞 ,也可能是冠状病毒攻?

Objective To study the pathologic characteristics and pathogenesis of circulating blood leucocytes infected by severe acute respiratory syndrome associated coronavirus (SARS CoV or SCV) in SARS patients. Methods Blood samples of 22 SARS patients were studied,and 4 healthy blood samples were observed as negative controls.The white blood cells were collected from whole blood. The ultrastructural characteristics were observed by transmission electron microscopy. CD45RO antibody was used for pre-embedding immunoelectron microscopy. The SARS viral sequence was detected with real-time polymerase chain reaction(RT-PCR). Results Coronaviru-like particles were founded in the leukocytes in 6 of the 22 blood samples. Five of them gave positive results in the the real-time PCR. The number of granulocytes was increased (P<0.05)and that of lymphocytes was discreased(P<0.05)respectively. Immunoelectron microscopy showed that CD45RO positeve T lymphocyte decreased to 6%～7%? Circulating lymphocytes had the highest percentage of infection. The morphologic characteristics of coronaviru-like particles were spherical or oval in shape, about 80～120 nm in diameter, with a dense round core and a clear halo around the core.A distinct membrane and club-shaped surface projections were seen in the periphery. The particles were located in the cytoplasm, the cisternae of endoplasmic reticulum, Golgi apparatus and vesicles. Virus entered cells by endocytosis or membrane fusion and was released through a budding process. Conclusion Our data suggested that lymphocytes, particularly T cells, were probably the target cells of SARS CoV. The viruses may actively infected the immune cells during SARS CoV acute infection phase and the destruction of target cells may be one of the important reasons for the death of the circulating leukocytes in SARS.