El embarazo humano: paradigma biológico de tolerancia y adaptación / Human pregnancy, a biological paradigm of tolerance and adaptation

ABSTRACT

This review analyses the changes in immunological tolerance, and the systemic and local hemodynamic changes observed along human pregnancy. To underscore the conceptual importance of tolerance and adaptation the background isprovided by the two main advocates ofthese ideas Gandhi and Darwin. The cognate factors that determine immunological tolerance (IT), systemic (SA) and local adaptation (LA) are múltiple; IT = desensitisation to paternal antigens, absence of HLA-A, roles of HLA-G, natural killer cells and their receptors; SA = decreased vascular resistance, plasma volume expansión, increased cardiac output and plasma renin activity; LA = prostacyclin, nitric oxide, kallikrein-kinin system, vasodilator arm of the renin angiotensin system, vascular endothelial growth factor (VEGF). A possible role of vasodilators in the crucial process of trophoblast invasión and uterine artery transformation is supported. The relevance ofan adequate adaptation to pregnancy is highlighted not only by the intragestational complications derivedfrom a defective process, such as intrauterine growth restriction, preterm birth, and preeclampsia -its foremost expression- but also by the long term cardiovascular complications ofthe mother and her offspring.