Roles Of Th1, Th17 Cells In The Development Of Pneumonia

Background and Objective:Adaptive immune response plays important roles in the host defense against infection.CD4+T lymphocyte subsets,including Th1 and Th17 cells are actively involved in the adaptive response by producing different cytokines. These cytokines participate in host defense by promoting antibody production or by enhancing the activation ofmacrophage.Pneumonia is one of common diseases,and has high morbidity and mortality rate both in the developing countries and developed countries. Although these kinds of diseases can be controlled by antibiotic,further understanding the mechanisms of CD4~+Th1,CD4~+Th17 mediated host defense will provide new light on the pathogenesis of infection diseases.Objective of this research is to investigate the roles of CD4~+Th1,CD4~+Th17 cells in the pathogensis of pneumonia and the dynamic expression of Th1 and Th17 cytokines in the patients with pneumonia.Methods:Plasma and peripheral lymphocytes were collected from 17 patients with pneumonia and 9 healthy controls.Lymphocytes were used for IL-17 and IFN-γexpression by intracellular staining(by Fluorescence Activated Cell Sorter FACS).Expression of plasma Th1 cytokine IFN-γand Th17 cytokine IL-17 were examined by ELI SA.The expression of IL-17 within peripheral lymphocytes was also measured at mRNA level by real-time PCR.Levels of CRP were also analyzed simultaneously.Results:1) Fluorescence Activated Cell Sorter analysis showed that the percentage of CD4~+IFN-γ~+ Th1 cells in peripheral lymphocytes were positively related to the diseases status of pneumonia;But percentage of CD4+IL-17+Th17 cells did not increase significantly in pneumonia patients compared to healthy controls;2) ELISA analysis showed that production of Th1 cell cytokine-- IFN-γ—in serum was significantly up-regulated in pneumonia group than in healthy controls and then decreased in follow-up after diseases relieved.Serum IL-17 in pneumonia patients was not up-regulated compared to that in healthy controls.3) Rea-time PCR also showed that IL-17 was not significantly up-regulated in pneumonia patients than that in controls.4) IFN-γbut not IL-17 showed positive relationship with the expression of CRP.Conclusion:Th1 but not Th17 cells might play important roles in host defense against pulmonary infection.Roles of Th17 cells in pathogenesis of pneumonia remain to be futher investigated.