Received February 12, 2023
Accepted August 21, 2023

The aim of this study was to carry out a systematic literature review to survey the main immune cells responsible for implantation failures. Articles were selected from PubMed, Embase and Virtual Health Library databases. Eligible works included publications between January 1, 2010 and April 24, 2022. As inclusion criteria: observational and case-control studies and as exclusion criteria: review articles, letters to the editor, abstracts, animal studies and case reports. The extracted data: day of collection, number of patients, control group, age of patients, type of sample used, immune cells and cytokines. As main findings in our mapping, we found that in peripheral blood, CD3+, CD4+, CD8+, CD16+, CD56+, CD57+, CD69+, CD154+, CD158a+, NKp46 cells were increased and markers CD4+, CD45+, Foxp3 and NKp46 were reduced. From the endometrial biopsies, there was an increase in CD3+, CD4+, CD5+, CD8+, CD16+, CD25+, CD45+, CD56+, CD57+, CD68+, CD127+ and a reduction in CD45+, CD56+, NKp46 and FoxP3 cells. Cytokines found increased in peripheral blood included IL-6, IL-10, IL-17, INF-γ, TGF-ß, TNF-α, while IL-4, IL-6, IL-10, IL-35, FoxP3 , TGF-ß, SOCS3 were reduced. As for the biopsies, there was an increase in IL-2, IL-6, IL-17, IL-22, IL-23, INF-A1, INF-B1, INF-γ, TNF-R and a reduction in L -6, IL -10, INF-γ, TGFß, TNF-α. We conclude that immune cells can be modulated during failure in pregnancy, but further studies are needed to elucidate the modulating effect of the immune system on the endometrium of these patients.