Expression of the Non-classical HLA-E, -F, -G Molecules in the Tumour Microenvironment

The human leukocyte antigen complex (HLA) is mainly known for its highly polymorphic classical molecules (class Ia and class II), which play a role in tumour immune modulation. The focus of this review, however, is on non-classical, significantly less polymorphic HLA-E, -F, and -G molecules (HLA-Ib), which are expressed by both immune and malignant cells in the tumour microenvironment. Recent findings indicate that the presence of HLA-G and -E in malignant tumours is associated with lowered overall survival of patients, whereas HLA-F is the least investigated and information about its role is more limited.