Characteristics Of Peripheral Blood Lymphocyte Subsets And Prognostic Factors In Patients With Severe Seasonal Influenza

ObjectiveThe objective of our study was to identify the characteristics of peripheral blood lymphocyte subsets in severe seasonal influenza patients and the dynamic changes of lymphocyte count before and after onset of influenza,and to find out the factors related to the severity and prognosis of the disease.MethodFrom August 2017 to April 2018,patients hospitalized in Peking Union Medical College Hospital with the diagnosis of influenza were to ken into study.There were a total of 42 cases,in which 24 cases were severe(including 6 deaths),the remaining 18 cases were mild.The peripheral blood lymphocyte subsets of the patients were detected by flow cytometry,and compared with 108 healthy people of similar age.Logistic regression and Cox regression were used to analyze the factors related to the severity and prognosis of the disease.Nine mild influenza A patients in a ward were selected to observe the dynamic changes of peripheral blood lymphocyte number before and after onset of influenza.Serum IL-6,IL-8,IL-10,and TNF-? levels were measured in 19 severe patients.Result1.The peripheral blood lymphocyte count and lymphocyte subsets count(B,NK,CD4+T,CD8+T)of patients with seasonal influenza were significantly lower than those of healthy controls.The CD8'T counts in severe death group was significantly lower than that in survival group.The ratio of T4/T8 was higher in severe influenza group,indicating that the proportion of decline in CD8+T count were larger than that of CD4'T,2.We found that CD8+HLA-DR/CD8+and CD8+CD38+/CD8+in mild and severe influenza were significantly higher than those in healthy controls.And these two activated proportions in severe illness were observed to be lower than that of mild illness in general.Meanwhile,CD8+HLA-DR/CD8+ and CD8+CD38+/CD8+in severe death group were significantly lower than those in severe survival group.3.Logistic and Cox regression analysis showed that CD8+T cell count CD8+and HLA-DR/CD8+T were both positively correlated with the survival rate of severe patients,indicating they might be protective factors.4.The peripheral blood lymphocyte counts in mild cases decreased significantly on the day of onset and within 1 day after onset,with an average decrease of 57.0%,and basically returned to the original level one week after onset.5.In severe patients,the serum levels of IL-6,IL-8 and other cytokines in the survival group were higher than those who succumbed in the first week of onset,while in second week,those in the death group became higher.Conclusion1.The lymphocyte subsets in peripheral blood of patients with seasonal influenza were significantly reduced.These findings were consistent with the immunological characteristics of respiratory viral infection,in which peripheral lymphocytes(especially T cells)migration to the respiratory tract in the early stage of infection and return to the peripheral after recovery.2.As an important component of cellular immunity against influenza virus,the counts and activation of CD8+T cells in peripheral blood were negatively correlated with the severity of the disease,which could be expected to be used as a prognostic indicator for severe influenza patients.