The 87G monoclonal antibody specifically recognizes Human Leukocyte Antigen G (HLA-G) which is encoded by HLA-G (major histocompatibility complex, class I, G). HLA-G is a nonclassical Major Histocompatibility Complex class I (MHC-Ib) molecule that is structurally related to the classical MHC class Ia antigens (HLA-A, -B, -C). Several HLA-G isoforms have been described including transmembrane HLA-G1, -G2, -G3, -G4 and soluble HLA-G5, -G6, and -G7. The 87G monoclonal antibody reportedly recognizes a conformationally-dependent epitope on the heterodimeric transmembrane HLA-G1 and soluble HLA-G7 isoforms that consist of an HLA-G alpha chain and β2-microglobulin (β2m). HLA-G1 is variably expressed on placental trophoblast cells, thymic epithelial cells, activated monocytes, macrophages, dendritic cells, and tumor cells. Heterodimeric HLA-G shows limited variation and binds a limited variety of self-peptides derived from intracellular proteins including histones and ribosomal proteins. This molecule binds to inhibitory receptors such as CD85d, CD85j, and CD158d that are differentially expressed by NK cells, T cells, monocytes, dendritic cells, and B cells. This interaction exerts suppressive regulation of immune responses and is thought to help safeguard maternal tolerance of the fetus during pregnancy. The 4H84 monoclonal antibody that reportedly recognizes denatured forms of HLA-G1 and HLA-G2 has also been described.
The antibody was conjugated to BD Horizon Red 718, which has been developed exclusively for BD Biosciences as a better alternative to Alexa Fluor® 700. BD Horizon Red 718 can be excited by the red laser (628 – 640 nm) and, with an Em Max around 718 nm, it can be detected using a 730/45 nm filter. Due to similar excitation and emission properties, we do not recommend using R718 in combination with APC-R700 or Alexa Fluor® 700.