Absence of HLA-G expression in macrophages of human decidua

PROBLEM: Macrophages - together with natural killer (NK) cells - constitute the majority of bone marrow derived infiltrating cells in the decidua. As interferon-gamma (IFN-gamma). 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-gamma, the question arises whether decidua macrophages in normal pregnancy express HLA-G. METHOD OF STUDY: The study was based on immunohistochemistry and flock cytometry. In order to exclude that potentially elusive soluble HLA-G was no I 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-G or -G2 as a secretory product of decidua macrophages with regard to interaction with HLA-G receptors present in or outside the decidua.