Immunotolerant functions of HLA-G

HLA-G is a nonclassical major histocompatibility complex class I molecule s electively expressed on cytotrophoblasts at the fetal-maternal interface? w here it plays a role in materno-fetal tolerance. In contrast to classical H LA-A, -B and -C class I molecules, HLA-G is characterized by (i) a tissue-r estricted distribution, (ii) a limited polymorphism and (iii) a transcripti on of spliced messenger RNAs encoding for at least four membrane-bound and two soluble HLA-G isoforms. Extensive studies over the past few years have identified HLA-G as a molecule involved in immune tolerance. In this review , attempts were made to summarize the current state of knowledge of the eff ects of HLA-G on both natural killer and T cell functions and their implica tions in materno-fetal tolerance and tumor immunosurveillance.