Clinical And Immunological Features Of Coronavirus Disease-2019(COVID-19)

Part Ⅰ Longitudinal characteristics of lymphocyte responses and cytokine profiles in the peripheral blood of SARS-Co V-2 infected patientsObjective:The dynamic changes of lymphocyte subsets and cytokines profiles of patients with novel coronavirus disease(COVID-19)and their correlation with the disease severity remain unclear.Methods:Peripheral blood samples were longitudinally collected from 40 confirmed hospitalized COVID-19 patients and examined for lymphocyte subsets by flow cytometry and cytokine profiles by specific immunoassays.Results:Of the 40 COVID-19 patients enrolled,13 severe cases showed significant and sustained decreases in lymphocyte counts[0.65(0.56-0.79)×10~9/L]but increases in neutrophil counts[4.66(3.56-5.84)×10~9/L]than 27 moderate cases[1.10(0.83-1.38)×10~9/L;1.98(1.48-2.91)×10~9/L].Further analysis demonstrated significant decreases in the counts of T cells,especially CD8~+T cells,as well as increases in IL-6,IL-10,IL-2 and IFN-γlevels in the peripheral blood in the severe cases compared to those in the moderate 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 moderate 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.Conclusion:The degree of lymphopenia and a proinflammatory cytokine storm is higher in severe COVID-19 patients than in moderate 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.Part Ⅱ Effects of corticosteroids and heparin on CD8+ T cells and D-dimers in patients with COVID-19Objective: To illustrate the effects of corticosteroids and heparin,respectively,on Coronavirus Disease 2019(COVID-19)patients’ CD8+ T cells and D-Dimer.Methods: In this retrospective cohort study involving 866 participants diagnosed with COVID-19,patients were grouped by severity.Generalized additive models were established to explore the time-course association of representative parameters of coagulation and immunity.Segmented regression was performed to examine the influence of corticosteroids and heparin upon CD8+ T cell and D-Dimer,respectively.Results: There were 541 moderate,169 severe and 156 critically ill patients involved in the study.Synchronous changes of levels of D-Dimer and CD8+ T cell in critically ill patients were observed.Administration of methylprednisolone before 14 days from onset of symptoms(DFS)compared with those after 14 DFS(β=0.154,95% CI=(0,0.302),p=0.048)or a dose lower than 40 mg per day compared with those equals to 40 mg per day(β=0.163,95% CI=(0.027,0.295),p=0.020)significantly increased the rising rate of CD8+ T cell in14 to 56 DFS.Similar analysis was also conducted with respect to heparin and the dynamic change of D-dimer.No significant effect was observed in 0-14(β=-0.147,p=0.745)and14-56(β=-0.108,p=0.410)DFS time frames for a patient administrated heparin within 14 DFS on D-dimer.Conclusion: An early low-dose corticosteroid treatment accelerated the regaining of CD8+T cell to help battle against SARS-Co V-2 in critical cases of COVID-19.The time of anticoagulation treatment with heparin had no significant effect on the changes of D-dimer.Part Ⅲ Characteristics of SARS-Co V-2-specific T cell memory in convalescent COVID-19individualsObjective: Increasing evidences suggest that patients who have recovered from COVID-19 can be reinfected,which challenge the fact that the cellular and/or humoral immunity facilitated by the primary infection may protect individuals from secondary encounters.This study aims to explore the characteristics of memory T cells in convalescent individuals(CIs),and to provide a scientific basis for the prevention and control of COVID-19.Methods: We collected peripheral blood samples and clinical data of CIs at the Department of Infectious Diseases,Union Hospital,Tongji Medical College,Huazhong University of Science and Technology from April 2020 to January 2021.Flow cytometry analysis was used to detect the characteristics of SARS-Co V-2-specific T cells in patients recovered from COVID-19.Results: Thirty-six convalescent individuals who resolved their SARS-Co V-2 infection were recruited.The median period between the disease onset and blood sampling was 187days(range: 83 to 354 days).CIs were stratified according to the severity of disease into asymptomatic(ACs: 25.00%,9/36),moderate(MCs: 55.56%,20/36),and severe COVID-19 cases(SCs: 19,44%,7/36).In general,the magnitude of SARS-Co V-2 memory T cell responses against S,N or M,either for the overall or individual cytokine production,were lower in ACs than in MCs and SCs,but the differences were not statistically significant(p>0.05).However,memory CD4 T cell responses against S,N,and M became undetectable in 44.44%(4/9)of ACs,but only in 5.00%(1/20)of MCs(p=0.022).Memory CD8 T cell responses against S,N,and M became undetectable in 66.67%(6/9)of ACs,but only in 15.00%(3/20)of MCs and 14.29%(1/7)of SCs,respectively.No AC showed memory CD8 T cell responses against multiple peptide pools,while 60.00%(12/20)of MCs and 71.43%(5/7)of SCs showed memory CD8 T cell responses to at least 2 different peptide pools.Positive correlations were observed between the magnitude of SARS-Co V-2memory T cell responses and total bilirubin(TB),alanine aminotransferase(ALT),aspartate aminotransferase(AST),lactate dehydrogenase(LDH),D-dimer,fibrinogen(FIB),while negative relationships were observed in white blood cell,IL-6,C-reactive protein,but the differences were not statistically significant(p>0.05).However,this trend was not observed in memory CD8+ T cell responses.Conclusion: SARS-Co V-2-specific T cell immunity is sustained in the majority of CIs.The memory T cell responses might be less durable in asymptomatic cases than in symptomatic cases.