T Cells Participate In The Immune Response To Listeria Monocytogenes Infection By Producing IFN-γ

BackgroundListeria monocytogenes(Lm)is a gram-positive anaerobic bacterium.After infecting,human generally perform fever and gastroenteritis.The infants,the elderly and the immunocompromised individuals are more serious,which always perform septicaemia,meningitis and mononuclear cells with extremely hyperplasia.Lm is one of the main pathogens that threaten human health because it can still grow and breed in the environment of 4 degrees Celsius.Interferon gamma(IFN-γ)is mainly produced by activated T cells and DC cells,which can play a protective role to defend intracellular bacterial infection.In mice infected by Lm,T cells can secrete a large number of IFN-γ to inhibit bacterial load,IFN-γ can further activate macrophages and NK cells to clear bacteria.At home and abroad,IFN-γ in human infected Lm is merely reported.Compared with healthy control,this paper is aimed to detect the expression of IFN-γ in Lm infectious human by ELISA and q-PCR,and detect the proportion of IFN-γ~+CD4~+T cell by flow cytometry.All of these can elaborate T cells participate in the immune response to Listeria monocytogenes infection by producing IFN-γ.ObjectiveThis paper intends to detect of serum IFN-γ mRNA and protein expression and simultaneously detect the proportion of IFN-γ~+CD4~+T cells among Lm and HC.This explore whether T cells inhibit Listeria monocytogenes infection by producing IFN-γ,which will provide preliminary theoretical basis for the Immune mechanism of Lm infection and the clinical application of re attenuated Lm.Methods1.Subjects investigated: The patients diagnosed as Lm infection in Zhu Ma-dian City People’s Hospital during May 2013-2015 May were divided into Lm group,the health people during the same period were divided into HC group.2.The collection and processing of samples: Peripheral blood mononuclear cells were collected from HC and Lm.The separated plasma are stored in-80℃refrigerator for ELISA.3.Detection the level of plasma IFN-γ: using human IFN-γ ELISA kit to detect the level of plasma IFN-γ.4.Detection the mRNA expression of IFN-γ subunit: extract the PBMC total RNA of HC and Lm.After reverse transcription,the expression of IFN-γ mRNA was detected by real-time quantitative PCR.5.Detection of IFN-γ~+CD4~+T cell proportion: Detection and analysis of IFN-γ~+CD4~+T cell proportion in samples by flow cytometry.6.Measurement data with standard deviation of mean and subtract(±s),compare the difference between the two groups using t test,the data were compared by chi-square test.Inspection level of alpha = 0.05,P < 0.05 for the difference was statistically.Results1.Specimen groups: There were 16 cases in Lm group,20 cases in HC group and there was no significant difference in gender and age.2.The results for ELISA: The content of plasma IFN-γ in Lm group was(7.26 ±4.99)pg/ml,which was higher than that in HC group(3.21 ± 1.22)pg/ml,and there was a significant difference.3.The results for real-time quantitative PCR: The relative expression of IFN-γ in peripheral blood mononuclear cells of Lm group was(118.15 ± 34.35),and the healthy control group was(99.24 ±19.46)times,the former was higher than the latter and the results were statistically significant.4.The results for flow cytometry: The percentage of IFN-γ~+CD4~+ T cells in group Lm was(8.61±5.22)%,the percentage of IFN-γ~+CD4~+T cells in group HC was(5.76 ± 1.23)%,the former was higher than that of the latter,and there was a significant difference.Conclusions1.IFN-γ mRNA and protein expression in peripheral blood of Lm infected patients were higher than those in healthy controls;2.The proportion of IFN-γ~+CD4~+ T cell was increased in Lm infected patients,which indicates T cells can participate in Lm infection immune by expression of IFN-γ.