Detection of HLA-G by a specific sandwich ELISA using monoclonal antibodies G233 and 56B

Human leukocyte antigen (HLA)-G, which is mainly expressed at the maternal-fetal interface, may play a role in the immune tolerance of the semi-allogenic fetus by the mother. Functional studies have shown that HLA-G is indeed a potential modulator of different immune responses. Therefore, it is of interest to study the level of expression of soluble HLA-G in several biological fluids derived from women with and without fertility problems. In order to measure soluble HLA-G, a reliable and sensitive HLA-G specific sandwich ELISA is required. Here, we describe such an ELISA in which G233 is used as the coating antibody and 56B as the detecting antibody. In comparison with two other assays, this assay shows highest responses to recombinant HLA-G and native HLA-G in primary trophoblast culture supernatant and high responses to HLA-G in amniotic fluid. No HLA-G in follicular fluid or preimplantation embryo culture supernatant could be detected.