Soluble HLA-G: Are they clinically relevant?
HLA-G is a non-classical HLA-class Ib molecule with multiple immunoregulatory properties. Its main function in physiological conditions is to abrogate maternal NK cell activity against foetal tissue and to establish immune tolerance at maternal-foetal interface. HLA-G is expressed not only as a membrane bound molecule on the surface of cells, but also as a soluble moiety in body fluids. The major isoforms of HLA-G present in serum are soluble HLA-G1 and HLA-G5 which are generated by shedding or proteolytic cleavage of the membrane bound isoform and by secretion of a soluble isoform, respectively. Here we review the data about soluble HLA-G (sHLA-G) serum levels in different pathological conditions, including immune-mediated disorders, transplantation and malignancies. In particular, we focus on sHLA-G expression and function in human neuroblastoma, a pediatric tumor, with special emphasis on a novel potential immuno escape mechanism utilized by NB to instruct monocytes to produce and release sHLA-G. Finally, the potential clinical relevance of sHLA-G serum levels is discussed.
Pistoia
Vito
V
Laboratory of Oncology, G.Gaslini Children's Hospital, Genoa, Italy. vitopistoia@ospedale-gaslini.ge.it
Morandi
Fabio
F
Wang
Xinhui
X
Ferrone
Soldano
S
D001327:Autoimmune Diseases / Q000097:blood / Q000276:immunology*; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D006680:HLA Antigens / Q000097:blood* / Q000276:immunology; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000097:blood* / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D009369:Neoplasms / Q000097:blood / Q000276:immunology*; D009447:Neuroblastoma / Q000097:blood / Q000276:immunology*; D014181:Transplantation Immunology