Macrophages of human first trimester decidua express markers associated to alternative activation

Problem: Depending on the type of their activation, macrophages may promote T(H)1- or T(H)2-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 (Mphi2). Results: The markers MS-1 (stabilin-1) and coagulation factor XIIIa were found expressed in the interior of decidua macrophages (DMphi). In contrast, indoleamine 2,3-dioxygenase (IDO), an enzyme induced in macrophages by IFNgamma, was not present in DMphi. Conclusions: First trimester DMphi display phenotypic markers associated to alternatively activated macrophages. In addition, absence of IDO indicates that DMphi are not under a predominant influence of IFNgamma.