title: Inhibitory NK receptor recognition of HLA-G: regulation by contact residues and by cell specific expression at the fetal-maternal interface.
abstract: The non-classical HLA-G protein is distinguished from the classical MHC class I molecules by its expression pattern, low polymorphism and its ability to form complexes on the cell surface. The special role of HLA-G in the maternal-fetal interface has been attributed to its ability to interact with specific receptors found on maternal immune cells. However this interaction is restricted to a limited number of receptors. In this study we elucidate the reason for this phenomenon by comparing the specific contact residues responsible for MHC-KIR interactions. This alignment revealed a marked difference between the HLA-G molecule and other MHC class I molecules. By mutating these residues to the equivalent classical MHC residues, the HLA-G molecule regained an ability of interacting with KIR inhibitory receptors found on NK cells derived either from peripheral blood or from the decidua. Functional NK killing assays further substantiated the binding results. Furthermore, double immunofluorescent staining of placental sections revealed that while the conformed form of HLA-G was expressed in all extravillous trophoblasts, the free heavy chain form of HLA-G was expressed in more distal cells of the column, the invasion front. Overall we suggest that HLA-G protein evolved to interact with only some of the NK inhibitory receptors thus allowing a control of inhibition, while permitting appropriate NK cell cytokine and growth factor production necessary for a viable maternal fetal interface.
authors.affiliation: The Lautenberg Center for General and Tumor Immunology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
authors.forename: Tsufit
authors.initials: T
authors.lastname: Gonen-Gross
authors.forename: Debra
authors.initials: D
authors.lastname: Goldman-Wohl
authors.forename: Berthold
authors.initials: B
authors.lastname: Huppertz
authors.forename: Dikla
authors.initials: D
authors.lastname: Lankry
authors.forename: Caryn
authors.initials: C
authors.lastname: Greenfield
authors.forename: Shira
authors.initials: S
authors.lastname: Natanson-Yaron
authors.forename: Yaron
authors.initials: Y
authors.lastname: Hamani
authors.forename: Ronit
authors.initials: R
authors.lastname: Gilad
authors.forename: Simcha
authors.initials: S
authors.lastname: Yagel
authors.forename: Ofer
authors.initials: O
authors.lastname: Mandelboim
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D005260:Female; D005455:Fluorescent Antibody Technique; D006680:HLA Antigens / Q000276:immunology*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011971:Receptors, Immunologic / Q000276:immunology*
chemical_list: D017931:DNA Primers; D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D011971:Receptors, Immunologic