Table 1.

Mechanisms of tolerance at the maternal-fetal interface in species with hemochorial placentation

Type of protection	Species	Genes/proteins	Reference
Antibody/complement lysis	Human	CD46, DAF, CD59	Kemper et al. (71)
	Mice	Crry	Xu et al. (18)
Low lymphocyte proliferation	Human	Progesterone	Ragusa et al. (72) and Hunt et al. (73)
Suppressor lymphocyte generation	Human	IL-10, TGF-β1	Lysiak et al. (15), McIntire et al. (16), and Wegmann et al. (17)
Regulation of HLA genes	Human	HLA-G, HLA-E	Hunt et al. (5, 6), Hunt (7), Hunt and Orr (32), and Le Bouteiller and Mallet (33)
Regulation of MHC class I genes	Primates	Mamu-AG, Paan-AG	Langat et al. (22, 23) and Slukvin et al. (74)
Prevent T-cell killing	Mice	FasL	Hunt et al. (27)
	Human	FasL	Kauma et al. (28)
Prevent T-cell killing	Mice	Indoleamine 2,3-dioxygenase	Baban et al. (75)
Prevent T-cell killing	Human	TNF-related apoptosis-inducing ligand (decoy receptors)	Phillips et al. (26)
Prevent T-cell killing	Human	TNF (soluble receptors)	Lien et al. (76)
Prevent T-cell killing	Human	B7H1	Petroff et al. (77)