PROBLEM: Macrophages – together with natural killer (NK) cells – constitute the majority of bone marrow derived infiltrating cells in the decidua. As interferon-γ (IFN-γ), a cytokine produced by NK cells, has been reported to induce expression of human leukocyte antigen (HLA-G) in monocytic cells, suggesting expression of HLA-G on decidua macrophages potentially stimulated by IFN-γ, the question arises whether decidua macrophages in normal pregnancy express HLA-G.
METHOD OF STUDY: The study was based on immunohistochemistry and flow cytometry. In order to exclude that potentially elusive soluble HLA-G was not detected by immunohistochemistry, we performed in addition RT–PCR of flow-sorted decidua macrophages.
RESULTS: Our findings indicate that HLA-G is not present on macrophages of first trimester or term decidua in either membrane-bound or soluble form. Transcripts for soluble HLA-G1 and -G2 were not detected.
CONCLUSIONS: We exclude a role of HLA-G on the surface of decidua macrophages or of soluble HLA-G1 or -G2 as a secretory product of decidua macrophages with regard to interaction with HLA-G receptors present in or outside the decidua.