Longitudinal characteristics of lymphocyte responses and cytokine profiles in the peripheral blood of SARS-CoV-2 infected patients
Liu, Jing et al.
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Background: The dynamic changes of lymphocyte subsets and cytokines profiles of patients with novel coro- navirus disease (COVID-19) and their correlation with the disease severity remain unclear. Methods: Peripheral blood samples were longitudinally collected from 40 confirmed COVID-19 patients and examined for lymphocyte subsets by flow cytometry and cytokine profiles by specific immunoassays. Findings: Of the 40 COVID-19 patients enrolled, 13 severe cases showed significant and sustained decreases in lymphocyte counts [0¢6 (0¢6-0¢8)] but increases in neutrophil counts [4¢7 (3¢6-5¢8)] than 27 mild cases [1.1 (0¢8-1¢4); 2¢0 (1¢5-2¢9)]. Further analysis demonstrated significant decreases in the counts of T cells, espe- cially CD8+ T cells, as well as increases in IL-6, IL-10, IL-2 and IFN-g levels in the peripheral blood in the severe cases compared to those in the mild cases. T cell counts and cytokine levels in severe COVID-19 patients who survived the disease gradually recovered at later time points to levels that were comparable to those of the mild cases. Moreover, the neutrophil-to-lymphocyte ratio (NLR) (AUC=0¢93) and neutrophil-to- CD8+ T cell ratio (N8R) (AUC =0¢94) were identified as powerful prognostic factors affecting the prognosis for severe COVID-19. Interpretation: The degree of lymphopenia and a proinflammatory cytokine storm is higher in severe COVID- 19 patients than in mild cases, and is associated with the disease severity. N8R and NLR may serve as a useful prognostic factor for early identification of severe COVID-19 cases. Funding: The National Natural Science Foundation of China, the National Science and Technology Major Proj- ect, the Health Commission of Hubei Province, Huazhong University of Science and Technology, and the Med- ical Faculty of the University Hospital Essen, Germany.