Human leukocyte antigen-G (HLA-G) expression in biliary epithelial cells is associated with allograft acceptance in liver-kidney transplantation

Alloreactive CD4+ and CD8+ T cells express the immunotolerant HLA‐G molecule in mixed lymphocyte reactions: in vivo implications in transplanted patients

“…In the context of human allotransplantation, these HLA-G molecules have been detected in graft biopsies and sera from patients who had undergone heart or kidney/ liver transplantation [4][5][6][7]. In these cases, HLA-G was associated with allograft acceptance, suggesting that titration of seric soluble HLA-G levels may be useful for monitoring the clinical course of allotransplantation [8].…”

“…Nevertheless, these drugs have serious side effects and further investigations of alternative immunotolerant strategies are sought [3]. Recently, nonclassical HLA class I molecule HLA-G, which is a wellknown tolerogeneic molecule, was found to contribute to allograft acceptance in transplanted patients [4][5][6][7][8].…”

“…In human allo-transplantation, ectopic HLA-G expression was demonstrated in graft biopsies and sera from heart-or kidney/liver-transplanted patients who exhibit a better graft acceptance [4,5,7]. However, the cells and mechanisms involved in such a de novo expression of HLA-G remain unknown.…”

Identification of a novel HLA-G+ regulatory population in blood: expansion after allogeneic transplantation and de novo HLA-G expression at graft-versus-host disease sites

“…3 It must be noted that, in these cases, expression of HLA-G was detected in situ in cells that are the primary targets of the immune system, e.g endomyocardial cells in heart grafts, 11,37 biliary epithelial cells in liver transplants , 12 and tubular epithelial cells after kidney transplantation. 35 Despite the large amount of information concerning HLA-G expression in solid organ transplantation, there have been no similar studies in the allogeneic hematopoietic cell transplantation (allo-HCT) setting.…”

“…Beyond physiological conditions, ectopic HLA-G expression has been found in tumor cells, 9 virus infected cells, 7 transplanted organs or immune cells infiltrating grafts, 3 and has been suggested to constitute an immune escape mechanism. After solid organ transplantation, HLA-G expression by the transplant organ [10][11][12] and high soluble HLA-G plasma levels 13,14 have been associated with better graft acceptance. After allogeneic bone marrow transplantation, soluble HLA-G plasma levels have been suggested to correlate with the occurrence of acute graft-versus-host disease (GvHD), suggesting an involvement of HLA-G in GvHD prevention.…”