The aim of this study was to carry out a systematic literature review to
investigate the main immune cells responsible for implantation failures. We
selected papers from PubMed, Embase and Virtual Health Library databases.
Eligible articles included publications between January 1, 2010 and April 24,
2022. Inclusion criteria were: observational and case-control studies; and the
exclusion criteria were: review papers, letters to the editor, abstracts, animal
studies and case reports. We extracted the following information: 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 the CD4+, CD45+, Foxp3 and NKp46 markers
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 IL-6, IL-10,
INF-γ, TGFß, TNF-α. We concluded that immune cells can be
modulated during pregnancy failure, but further studies are needed to elucidate
the modulating effect of the immune system on the endometrium of these
patients.