Up-regulation of human leukocyte antigen G expression in primary cutaneous malignant melanoma associated with host-vs-tumor immune response.

Human leukocyte antigen G (HLA-G) is one of the molecules implicated in immunotolerance. To investigate the role of HLA-G in primary cutaneous malignant melanoma (CMM), a series of 47 skin melanocytic lesions were immunohistochemically evaluated. The correlation between HLA-G expression and CMM clinicohistopathological data and Bcl-2 expression was also analyzed. HLA-G expression was detected in a variety of cell types. No significant difference in HLA-G expression was observed between malignant and non-malignant melanocytic lesions. HLA-G expression was significantly correlated with the inflammatory infiltration and Bcl-2 expression, whereas no significant correlation with ulceration, tumor thickness, clinical stage, histopathological subtypes were observed. HLA-G expression may be the result of host immune reaction in tumor microenvironment rather than a malignant feature of CMM.