Immune biomarkers in cases of recurrent pregnancy loss and recurrent implantation failure

Reproductive failures, such as recurrent pregnancy loss (RPL) and recurrent implantation failures (RIF) are a major challenge for reproductive medicine. The current management of RPL and RIF cases identifies some causes for unsuccessful pregnancy in up to half of patients. Several studies have suggested that immune disorders are responsible for an important portion of unexplained cases of RPL and RIF. Moreover, the immune abnormalities responsible for reproductive failures can be classified into disorders related to autoimmunity and changes in cellular immunity. Antiphospholipid syndrome (APS), testing for antiphospholipid (aPL) antibodies, antinuclear antibodies, and antithyroid antibodies are identified as biomarkers of autoimmunity that can predict reproductive failure. The cellular immune response in cases of RPL and RIF can be investigated through the study of natural killer (NK) cells (uterine and peripheral blood) and T lymphocytes (T helper [Th]-1, Th-2, regulatory T and Th-17 cells). Several types of laboratory assays have been used to evaluate the endometrial immune microenvironment, such as the endometrial immune profile and decidualization score. However, the effectiveness of the treatment of RPL and RIF with immunomodulatory drugs has not yet been confirmed. Recently, a group of experts from the International Federation of Gynecology and Obstetrics and the European Society of Human Reproduction and Embryology recommended the investigation of some immune factors and treatment with immunosuppressants in women with RPL. In conclusion, it is important to consider immune abnormalities when managing women with RPL and RIF. The use of immunotherapies must be personalized and based on a specific diagnosis to obtain favorable outcomes.