Citation Mor G, Cardenas I. The immune system in pregnancy: a unique complexity. Am J Reprod Immunol 2010AbstractPlacental immune response and its tropism for specific viruses and pathogens affect the outcome of the pregnant woman’s susceptibility to and severity of certain infectious diseases. The generalization of pregnancy as a condition of immune suppression or increased risk is misleading and prevents the determination of adequate guidelines for treating pregnant women during pandemics. There is a need to evaluate the interaction of each specific pathogen with the fetal/placental unit and its responses to design the adequate prophylaxis or therapy. The complexity of the immunology of pregnancy and the focus, for many years, on the concept of immunology of pregnancy as an organ transplantation have complicated the field and delayed the development of new guidelines with clinical implications that could help to answer these and other relevant questions. Our challenge as scientists and clinicians interested in the field of reproductive immunology is to evaluate many of the ‘classical concepts’ to define new approaches for a better understanding of the immunology of pregnancy that will benefit mothers and fetuses in different clinical scenarios.

The comparison of the immunological state of pregnancy to an immunosuppressed host-graft model continues to lead research and clinical practice to ill-defined approaches. This Review discusses recent evidence that supports the idea that immunological responses at the receptive maternal-fetal interface are not simply suppressed but are instead highly dynamic. We discuss the crucial role of trophoblast cells in shaping not only the way in which immune cells respond to the invading blastocyst but also how they collectively react to external stimuli. We also discuss the role of the microbiota in promoting a tolerogenic maternal immune system and highlight how subclinical viral infections can disrupt this status quo, leading to pregnancy complications.

The concept that pregnancy is associated with immune suppression has created a myth of pregnancy as a state of immunological weakness and, therefore, of increased susceptibility to infectious diseases. A challenging question is whether the maternal immune system is a friend or a foe of pregnancy. In this review, we discuss data associated to the role of the immune system during pregnancy. We propose a new paradigm in terms of the fetal-maternal immune interaction as well as the immunological response of the mother to micro-organism. Our challenge is to better understand the immunology of pregnancy in order to deliver the appropriate treatment to patients with pregnancy complications as well as to determine public policies for the protection of pregnant women during pandemics. Keywordsinflammation; pregnancy; TH1/TH2; macrophages; dendritic cellsThe idea that pregnancy is associated with immune suppression has created a myth of pregnancy as a state of immunological weakness and, therefore, of increased susceptibility to infectious diseases. A challenging question is whether the maternal immune system is a friend or a foe of pregnancy. In order to discuss this question we will first review some fundamental concepts associated with the immune system and pregnancy.A fundamental feature of the immune system is to protect the host from pathogens. This function depends upon the innate immune system's capacity to coordinate cell migration for surveillance and to recognize and respond to invading microorganisms. During normal pregnancy, the human decidua contains a high number of immune cells, such as macrophages, natural killer (NK) cells and, regulatory T cells (Treg) [1][2][3] [2,4,5]. B cells are absent from the adaptive immune system, but T lymphocytes constitute about 3-10% of the decidual immune cells [6]. During the first trimester, NK cells, dendritic cells, and macrophages infiltrate the decidua and accumulate around the invading trophoblast cells [7,8]. Interestingly, depletion of immune cells, instead of helping the pregnancy, terminates the pregnancy. Thus, deletion of macrophages, NK cells, or dendritic cells (DC) has deleterious effects on placental development, implantation, or decidual formation [9][10][11][12][13][14]. In elegant studies, it has been shown that in the absence of NK cells, trophoblast cells are not able to reach the endometrial vascularity leading to termination of the pregnancy [12]. These studies suggest that uNK cells are critical for trophoblast invasion in the uterus. Similarly, depletion of DCs prevented blastocyst implantation and decidual formation [15]. Indeed, this Consequently, the presence of immune cells at the implantation site is not associated with a response to the "foreign" fetus but is attracted to facilitate and protect the pregnancy. Therefore, the immune system at the implantation site is not suppressed-on the contrary it is active, functional, and is carefully controlled.Is the systemic immunity of the mother suppressed? Although we can find numerous studie...

Chemotherapy eliminates the bulk of the tumor but it leaves a core of cancer cells with high capacity for repair and renewal. The molecular properties identified in these cells may explain some of the unique characteristics of CSCs that control self-renewal and drive metastasis. The identification and cloning of human OCSCs can aid in the development of better therapeutic approaches for ovarian cancer patients.

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