A novel subset of putative stem/progenitor CD34(+)Oct-4(+) cells is the major target for SARS coronavirus in human lung

Chen, Yongxiong; Chan, Vera Sau-Fong; Zheng, Bojian; Chan, Kelvin Yuen-Kwong; Xu, Xiaoning; To, Leo Yuk-Fai; Huang, Fang-Ping; Khoo, Ui-Soon; Lin, Chen-Lung Steve

Admittedly, the pathogenesis of SARS is still unclear and no satisfactory explanation for a complete picture has been provided by reports in the literature or by this study. Nevertheless, we present clear evidence that putative stem/progenitor CD34 Ï© Oct4 Ï© cells are the major target for SARS-CoV infection in the human lung. With our fi ndings, we postulate that although L-SIGN -mediated viral entry into cytokeratin Ï© respiratory epithelia leads to viral degradation ( 13 ) , infection of CD34 Ï© Oct4 Ï© cells may result in cell death (cytopathy) and the production of proinfl ammatory cytokines or other soluble mediators. The death of the stem/progenitor cells and the resulting local immuno-dysregulation (e.g., cytokine storm from infi ltrating immune cells [ Fig. S5 ], including macrophages, and/or from the infected CD34 Ï© Oct4 Ï© cells) may together contribute to alveolar cell damage, loss of repair capacity, and respiratory insuffi ciency as clinically observed. Isolation and purifi cation of these CD34 Ï© Oct4 Ï© cells are underway to further examine their role in the pathogenesis.