a1 AG Reproduktionsimmunologie, Institut für Medizinische Immunologie, Charite, Medizinische Universität zu Berlin, Germany.
Pregnancy success remains a fascinating phenomenon to immunologists as it defies the immunological rules of rejection. Although it was previously thought that the maternal immune system does not see the fetus, it is now well documented that fetal cells reach the maternal body and encounter host immune cells. Natural tolerance mechanisms following this interaction remain to be fully elucidated. This article reviews the current literature on mechanisms of adaptive immunity, with emphasis on regulatory T cells and heme oxygenase 1 (HO-1). We propose a scenario in which regulatory T cells create a tolerant microenvironment at the fetal–maternal interface characterised by the presence of tolerance-associated molecules such as HO-1, which has been shown to be of vital importance for fetal survival.
c1 *Corresponding author: Ana Claudia Zenclussen, AG Reproduktionsimmunologie, Institut für Medizinische Immunologie, Charite, Medizinische Universität zu Berlin, CVK, Biomedizinisches Forschungszentrum, Raum 2.0534, Augustenburger Platz 1, 13353 Berlin, Germany. Tel: +49 30 450 559886; Fax: +49 30 450 559986; E-mail: [email protected]