HLA-G expression in tumor cells is deleterious to the host because of its interaction with leukocyte receptors, particularly ILT-2 and ILT-4, which downregulate the cytotoxic activity of CD8+ T and natural killer (NK) cells and inhibit antigen presentation, lymphocyte proliferation, and antibody formation [15,16]. This evidence concerns the gene HLA-G and neoplasm.