Human uterine immune cells in endometrium and pregnancy – Martin Ivarsson team

The Martin Ivarsson team studies uterine immune cells in the endometrium and the decidua (endometrium during pregnancy). We explore the heterogeneity and function of the cells and try to understand their role for establishment and maintenance of healthy pregnancies.

The Martin Ivarsson team is part of the Niklas Björkström research group at the Center for Infectious Medicine (CIM).

About our research

Our research interest is in the dynamics, variations in phenotype and function of human uterine immune cells with a particular focus on natural killer (uNK) cells, in non-pregnant and pregnant women. These cells can be said to be misnamed since they are in fact not natural killers. Instead, more and more studies indicate they regulate the placentation (attachment of the embryo and establishment of the placenta) by interacting with placenta-derived trophoblast cells, other immune cells in the uterus, as well as with cells lining the spiral arteries of the uterus. The uNK cells increase in frequency and change phenotype during each menstrual cycle and develop further in the event of a pregnancy.

Work from us and other groups have shown that the uNK cell receptor profile (which govern the cell’s function) is highly individual and that it is recapitulated each menstrual cycle. Moreover, the uNK cell profile is distinct from that of conventional NK cells in the same woman. This indicates a tight regulation of the uNK cells, which likely has to do with an important role played by them. This role remains to be fully understood.

Clinical collaborations and tissue samples for research

We make use of several clinical collaborations to obtain relevant tissue for our research. These include decidua and placenta tissue from elective terminations, endometrium from hysterectomies, menstrual blood from healthy volunteers and from women undergoing IVF. We also study patients suffering from spontaneous unexplained bleedings during pregnancies, where we try to understand what the bleeding contains, and whether it has a link to risk for miscarriage.

Methods used in our research

Methods we use include cytometry, confocal microscopy as well as more recent RNA sequencing approaches (10x Genomics and ATAC sequencing). We also study the protein content of serum, plasma, and saliva from our patient cohorts and for thus we use ELISA or OLINK’s PEA technology. With these techniques we unravel the phenotype and function of the different cells at the fetal/maternal interphase, and then seek link this information to e.g. pregnancy outcome for patients doing IVF, or to risk for miscarriage for women presenting with vaginal bleedings early in pregnancy. The long-term aim is to help develop new diagnostic and treatment methods for reproduction medicine.


Selected publications


  • Wenner-Gren Stiftelserna
  • Vetenskapsrådet
  • Åke Wibergs stiftelse
  • Svenska Läkaresällskapet
  • Karolinska Institutets fonder