Study On The Frequency,phenotype And Function Of Peripheral Blood Mucosal-associated Invariant T(MAIT) Cells In Patients With Gastric Cancer

Objective To explore the changes in frequency,phenotype and function of mucosa-associated constant T(MAIT)cells in peripheral blood of gastric cancer(GC)patients,and whether the changes are related to chemotherapy factors.To explore the changes of MAIT cell-related cytokines and granzyme-B(Gr-B)levels in serum of GC patients.To explore the relationship between peripheral blood MAIT cells frequency and its clinical parameters in patients with gastric cancer,so as to provide an experimental basis for the T cells study of gastric cancer immunotherapy.Methods We collected about 2ml clinical heparinization peripheral blood of GC patients and HC,with density gradient centrifugation preparing for the peripheral blood mononuclear cells(PBMCs),and finally joined the fluorescent antibody before flow cytometry detection.To determine the changes of peripheral blood MAIT cells frequency,the phenotypic CD4 and CD8,and the important immunophenotypes such as pd-1.Some samples were stimulated by PMA+ ionomycin in vitro for the functional studies of MAIT cells.In addition,we also collected the supernatants from the blood samples to detect the levels and changes of MAIT cell-related cytokines and granzyme-B(Gr-B)in peripheral blood serum by CBA(Cytometric Bead Array)kit.Results 1.In healthy adults,the frequency and absolute numbers of MAIT cells decreased with age(p < 0.01,p < 0.01),but were independent of gender(p =0.957,p =0.623),Hp infection(p =0.255,p =0.089),and BMI(p =0.128,p =0.084).2.In disease groups,compared with HC,the frequency and absolute number of peripheral MAIT cells were decreased in GC patients(p =0.001,p <0.001),while the frequency and absolute number of peripheral MAIT cells were unchanged in GC patients before and after once chemotherapy(p =0.81,p =0.519).3.On the basis of CD4 and CD8 typing,we performed the analysis of peripheral blood MAIT cells frequency.Compared with HC,the frequency of CD4-MAIT cells in GC without chemotherapy was lower than that in HC(p =0.018),and was also lower than GC with chemotherapy(p =0.023).Moreover,the frequency of CD4-CD8+MAIT cells in GC without chemotherapy was lower than that in HC(p =0.036),and the others had no changes.4.In the determination of the immunophenotype of MAIT cells,only PD-1 showed differences between GC patients and HC(p =0.042),while CD69 and Tim-3 showed no differences(p =0.474,p =0.369).5.In the functional study,there was no change in the proportion of IFN-γ+ MAIT cells(p =0.401)and TNF-α+ MAIT cells(p =0.332)in the peripheral blood of GC patients compared with HC.This is also the same meaning that there was no change in the function of these two cytokines secreted by MAIT cells in peripheral blood of GC patients.6.In addition,there were no correlations between the proportions of peripheral blood MAIT cells in GC patients and the levels of their tumor markers CEA(p =0.401),CA19-9(p =0.401),and CA72-4(p =0.401).There were also no correlation with tumor stage(p =0.624,p =0.484).CBA results showed that the serum levels of IFN-γ,TNF-α,IL-17 and IL-2 in the peripheral blood of GC patients had no changes compared with HC,but only Gr-B was decreased(p <0.001).Conclusion 1.The frequency of peripheral blood MAIT cells in GC patients was decreased,which may be related to cell depletion.2.Chemotherapy factors had no effect on the frequency of peripheral blood MAIT cells in GC patients.3.The expression level of MAIT cells PD-1 phenotype in GC patients was higher.4.The function of peripheral blood MAIT cells of GC patients remains unchanged.5.MAIT cells may become a new and important direction in immunotherapy study of gastric cancer.