HLA-G بررسی ساختار و عملکرد

HLA-G is a nonclassical HLA class Ib, which is located on chromosome 6 (6p.21.3). In contrast to HLA class I molecules, HLA-G has restricted polymorphism. Expression of this molecule in the physiological conditions limits to certain tissues such as thymus, cornea, nail matrix, trophoblast and pancreas. Up to now, 50 alleles of HLA-G molecules have been discovered with 16 distinct functional proteins. Alternative splicing of RNA primary transcript results in seven isoforms including four membrane bound (G1-G4) and three soluble (G5-G7) isoforms. Today, many roles have been described for HLA-G molecule in various physiological and pathological conditions such as pregnancy, transplantation, autoimmune and infectious diseases. Induction of HLA-G expression is one of the immune system evasion mechanisms in some infectious and tumoral conditions. The importance of HLA-G expression during pregnancy and establishment of fetal-maternal tolerance has been proved. In this review paper we discussed the genetics, biology and the role of HLA-G molecule in some physiological and pathological conditions.