The low rate of HLA class I molecules on the human embryonic stem cell line HS293 is associated with the APM components' expression level.
Human embryonic stem cells (hESCs) represent a promise for future strategies of tissue replacement. However, there are different issues that should be resolved before these cells can be used in cellular therapies; among others, the rejection of transplantable hESCs as a result of HLA incompatibility between donor cells and recipients. The hESCs exhibit a weak HLA class I expression on the cell surface, but today the responsible mechanisms are unknown. We have analyzed the level expression of HLA class I heavy chain, beta2-microglobulin (beta2-m), and antigen-processing machinery (APM) components (TAP1, TAP2, LMP2, LMP7, and Tapasin) using the HS293 hESC line by real-time quantitative RT-PCR. This analysis has revealed a low expression of beta2-m, HLA-B, and Tapasin, and an absence of expression of: TAP1, TAP2, LMP2, and LMP7 genes in the HS293 hESC line respect to the embryoid bodies (EBs) and the induced stem cells with IFNgamma (with significant differences, p<0.05). The lack or loss of HLA class I molecules due to the down-regulation of the APM components has been frequently found in tumors of different histology as specific mechanisms of immune-evasion. We described for the first time in this report that the hESCs shared similar mechanisms with respect to tumor cells responsible for the weak HLA class I expression on the cell surface.
Cabrera
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Stem Cell Bank of Andalucia (Spanish Central Node), Hospital Universitario Virgen de las Nieves, Granada, Spain. carmenm.cabrera.sspa@juntadeandalucia.es
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D015415:Biomarkers / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D015415:Biomarkers; D015395:Histocompatibility Antigens Class I; D012333:RNA, Messenger