HLA-G protein expression could play a role in evasion of tumor immune surveillance. Accumulating evidence demonstrates that HLA-G is expressed in different types of malignancies, including colorectal cancer (CRC). The purpose of the current study was to further unravel whether HLA-G protein expression could play a role in immune evasion of CRC. Therefore, to firmly establish HLA-G protein expression, eight early passage human CRC cell lines and five human rectal cancer tissues were analyzed by western blot analysis. The results obtained by western blot analysis were compared with immunohistochemistry on tumor tissue sections of the same patient. Furthermore, multiple monoclonal antibodies (mAbs), 4H84, MEM-G/1 and 5A6G7, targeting HLA-G were used to unravel staining patterns. We showed that results obtained with immunohistochemistry did not correlate with protein expression detected by western blot analysis, using three different HLA-G targeting mAbs. Furthermore, with respect to the specificity of the mAbs employed, additional immune reactivity was detected using the mAbs MEM-G/1 and 5A6G7 in western blot analysis with K562 control cell lines overexpressing HLA-A2 or HLA-G, all tumor tissues and in two out of eight CRC cell lines. Based on the current study and our previously reported results, we conclude that claiming HLA-G plays a role in immune modulation of CRC seems premature, as results from anti-body based detection of HLA-G protein remain inconclusive. Until the time that detection of HLA-G is sensitive enough to detect all aspects of HLA-G expression in biological samples, rather than transfected cells or long time cultured cell lines, conclusions should be drawn with great care.

HLA-G蛋白表达可能在逃避肿瘤免疫监视中发挥作用。越来越多的证据表明，HLA-G在不同类型的恶性肿瘤中表达，包括结直肠癌（CRC）。本研究的目的是进一步阐明HLA-G蛋白表达是否可以在CRC的免疫逃逸中发挥作用。因此，为了牢固地建立HLA-G蛋白表达，通过蛋白质印迹分析对八种早期传代的人类CRC细胞系和五种人类直肠癌组织进行了分析。通过蛋白质印迹分析获得的结果与同一患者肿瘤组织切片上的免疫组织化学进行了比较。此外，使用多种靶向HLA-G的单克隆抗体（mAb），4H84，MEM-G / 1和5A6G7揭示了染色模式。我们显示，使用三种不同的靶向HLA-G的mAb，通过免疫组织化学获得的结果与通过蛋白质印迹分析检测到的蛋白质表达不相关。此外，关于所用mAb的特异性，使用mAbs MEM-G / 1和5A6G7在过表达HLA-A2或HLA-G的K562对照细胞系，所有肿瘤组织和组织中的Western印迹分析中检测到其他免疫反应性8个CRC细胞系中有2个。根据当前的研究和我们先前报道的结果，我们得出结论，声称HLA-G在CRC的免疫调节中起作用似乎为时过早，因为基于抗体的HLA-G蛋白检测结果尚无定论。直到HLA-G的检测足够灵敏以检测生物样品中HLA-G表达的各个方面之前，