Characterization of Circulating Mucosal Associated Invariant T cells in Colorectal Cancer Patients

Abstract Background: Although MAIT cells regulate the pathogenesis of various inflammatory diseases, their roles in the development of colorectal cancer are still unclear. The objectives of this study is to investigate the level of circulating MAIT cells and the level of expression of the membranous KIRs receptors among CRC patients and control subjects. Peripheral blood mononuclear cells (PBMCs) were isolate and of MAIT cells were phenotypically identified by flow cytometry using various monoclonal antibodies. The presence of HLA-C1 and HLA-C2 groups were typed by PCR. Results: The result showed that the percentage of MAIT cells was slightly higher in the control subjects than in in all stages of CRC patients. Stratification analysis of 46 CRC patients indicated that the percentages of circulating MAIT cells were lower in stage II and higher in stages III, and IV. A higher frequency of HLA - C2 among patients with CRC (87%) compared with control subjects (74.4%) was detected. The protein expression of MAIT cells associated phenotyping antigens and some KIR receptors such as CD45RA, CD45RO, CD62L, CD11a, CD158a, CD158b, CD158e and CD158f were reported. There was a reduction in CD45RO, CD158a, CD158e and CD158f expression in CRC patients. The frequencies of circulating MAIT cells had not been reduced in patients with colorectal cancer.Conclusions: The number and level of circulating MAIT cells were evaluated in peripheral blood of CRC patients and control subjects. We compared the frequency of CD158a+MAIT cells in all stages of CRC and control subjects in the presence of its ligand HLA-C2 and found a reduction in all stages of CRC. We stratified CRC patients and found that CD158b+ MAIT cells were decreased as the diseases progress to advancing cancer stages. When comparing the proportion of CD158a and b+ MAIT cells in all stages with control subjects, the results showed inverse correlation with cancer stages in CRC patients and the median gradually decrease in each stage.