HLA-G intracellular expression in decidua trophoblasts in a normal term placenta: a confocal and transmission electron microscopy study.

ABSTRACT The placenta acts as an immunological barrier between the mother and the fetal “graft”, allowing two antigenically different organisms to tolerate one another. Human leukocyte antigen-G (HLA-G) may be involved in the mechanisms modulating the maternal immune system. Indeed, several authors have found that HLA-G is primarily expressed on the placental trophoblast plasmatic membrane. However, pregnancy still remains a major immunological enygma and current studies are far from clarifying the mystery. To further investigate this matter, we undertook the current study, using laser scanning confocal (LSCM) and transmission electron microscopy (TEM), in order to deepen knowledge on HLA-G expression in placentas from normal pregnancies, following a spontaneous term delivery. Unexpectedly, we observed that HLA-G expression includes both vesicles and clusters, localized in the cytosol or close to the nucleus. Keywords: placenta, HLA-G, confocal microscopy, transmission electron microscopy.