Which cells express Human Leukocyte Antigens (HLA) during pregnancy?

The expression of Human Leukocyte Antigens (HLA) during pregnancy is a complex and crucial process that involves various cell types. Non-trophoblastic cells, such as maternal and fetal cells, express different HLA molecules. The presence of these antigens plays a significant role in the maternal-fetal relationship by helping the immune system recognize and tolerate the fetus.

In the context of pregnancy, while trophoblastic cells, including cytotrophoblasts and syncytiotrophoblasts, are known for their specific expression of certain HLA molecules (particularly HLA-G, HLA-C), other non-trophoblastic cells also express HLA, contributing to the immunological interactions between the mother and the fetus. The diverse expression of HLA across all non-trophoblastic cells illustrates the complexity of maternal-fetal immune tolerance, which is essential for a successful pregnancy.

Therefore, the correct answer reflects the comprehensive expression of HLA by all non-trophoblastic cells, which is crucial for modulating maternal immunity and facilitating a successful pregnancy without the rejection of the genetically distinct fetus.