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Tom Erkers [1] and Arwen Stikvoort [2] and Michael Uhlin [3; 4]
Academic Editor: Shay Soker
1, Division of Blood and Marrow Transplantation, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA, stanford.edu
2, Department of Oncology-Pathology, Karolinska University Hospital Huddinge, Stockholm, Sweden, ki.se
3, Department of Clinical Immunology and Transfusion Medicine (KITM), Karolinska University Hospital Huddinge, Stockholm, Sweden, ki.se
4, Department of Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden, ki.se
Received Jul 28, 2017; Accepted Oct 11, 2017
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Immunological tolerance and defensive mechanisms of foreign tissue were first discussed by Murphy [1] and Owen [2]. However, the concept of acquired immune tolerance was introduced definitively by Billingham and Medawar in 1953 [3].
The sites at which the fetal and maternal tissues are in contact can be referred to as the fetomaternal interface and can be divided into two compartments. The first of which is between the maternal decidua and the fetal chorionic plate and chorionic membrane. Depending on whether the decidua is in contact with the site of implantation or with the fetal membranes is referred to as the decidua basalis or decidua parietalis, respectively. The second interface is where the maternal blood is in contact with the placental body and interacts with fetal trophoblasts. Thus, fetal and maternal tissues are not completely separated and immune cells have access to fetal tissues, driving complex tolerogenic immunological mechanisms to prevent rejection of the fetal allograft. The objective of this review is to discuss some of these mechanisms in the light of the current literature, with particular emphasis on lymphocyte function at the fetomaternal interface and how these cells may contribute to immune modulation during pregnancy.
2. T Cell Priming and Fetal Antigen Presentation
The placenta can be regarded as a haploidentical transplant. However, transplantation of a solid organ or hematopoietic stem cells leads to rejection or graft-versus-host disease (GVHD) without proper immunosuppressive interventions, while pregnancy is tolerated. Thus, there must be fundamental differences in these two entities in the priming and effector responses of the immune system to...