Macrophages of Human First Trimester Decidua Express Markers Associated to Alternative Activation

Problem: Depending on the type of their activation, macrophages may promote TH1‐ or TH2‐type of immune responses. To date, not much is known about the activation phenotype of decidua macrophages, which – together with NK cells – constitute the majority of bone marrow derived cells at this location. Method of study: The study was based on analysis of healthy first trimester decidua by immunohistochemistry and flow cytometry. We analyzed expression of markers characteristic for alternatively activated macrophages (Mφ2). Results: The markers MS‐1 (stabilin‐1) and coagulation factor XIIIa were found expressed in the interior of decidua macrophages (DMφ). In contrast, indoleamine 2,3‐dioxygenase (IDO), an enzyme induced in macrophages by IFNγ, was not present in DMφ. Conclusions: First trimester DMφ display phenotypic markers associated to alternatively activated macrophages. In addition, absence of IDO indicates that DMφ are not under a predominant influence of IFNγ.