KIR are receptors on uterine natural killer (uNK) cells that can bind to HLA-C on embryos. There’s different KIRs on uNK cells that can be activating or inhibitory that can affect embryo implantation. The HLA-C genes inherited by the embryo might not be compatible with the KIRs on the maternal uNK cells for effective implantation.
Synonyms:
Killer-cell immunoglobulin-like receptor, KIR