Pregnancy and immune tolerance

Kisspeptin is made in enormous amounts by the placenta, which is where it was first isolated, and Russian groups in Perm have followed what it does to the mother's immune cells. Their work describes it shaping monocyte and neutrophil behaviour and contributing to the tolerance that stops a mother rejecting a pregnancy. That is a long way from tanning or testosterone, and it is a reminder that this molecule was a placental peptide before it was anything else.