HLA-G differs from the other MHC class I genes by its low polymorphism and alternative splicing that generates seven HLA-G proteins, whose tissue-distribution is restricted to normal fetal and adult tissues that display a tolerogenic function toward both innate and acquired immune cells. The soluble HLA-G5 isoform encoded by intron-4 retaining spliced transcript has been previously detected in vivo in sera and grafts from transplanted patients who had significantly better graft acceptance. It has been demonstrated that HLA-G5-mediated graft tolerance involves the induction of immunosuppressive T cells. These findings provide evidence supporting the tolerogenic properties of HLA-G and emphasize its potential application as a relevant therapeutic candidate capable of limiting allograft rejection. Recently, using specific ELISA to analyze the presence of sHLA-G molecules in culture supernatants of early embryos obtained by in vitro fertilization (IVF) before transfer, several reports demonstrated that positive embryo implantations occurred with embryo secreting sHLA-G molecules. BioVendor’s HLA-G5 is a recombinant protein expressed in mammalian (human) cell line HEK293 and exhibits folding and glycosylation patterns of native human protein. The C-terminal tag sequence (AAADYKDDDDK) has been added to make the detection, immobilization or purification via anti-Flag antibodies possible. The protein has been lyophilized from 50 mM NaCl/ 20 mM Tris buffer and does not contain any inert protein or antimicrobial agents.