title: Induction of alloantigen-specific anergy in human peripheral blood mononuclear cells by alloantigen stimulation with co-stimulatory signal blockade.
abstract: Allogeneic hematopoietic stem cell transplantation (AHSCT) offers the best chance of cure for many patients with congenital and acquired hematologic diseases. Unfortunately, transplantation of alloreactive donor T cells which recognize and damage healthy patient tissues can result in Graft-versus-Host Disease (GvHD). One challenge to successful AHSCT is the prevention of GvHD without associated impairment of the beneficial effects of donor T cells, particularly immune reconstitution and prevention of relapse. GvHD can be prevented by non-specific depletion of donor T cells from stem cell grafts or by administration of pharmacological immunosuppression. Unfortunately these approaches increase infection and disease relapse. An alternative strategy is to selectively deplete alloreactive donor T cells after allostimulation by recipient antigen presenting cells (APC) before transplant. Early clinical trials of these allodepletion strategies improved immune reconstitution after HLA-mismatched HSCT without excess GvHD. However, some allodepletion techniques require specialized recipient APC production and some approaches may have off-target effects including depletion of donor pathogen-specific T cells and CD4 T regulatory cells .One alternative approach is the inactivation of alloreactive donor T cells via induction of alloantigen-specific hyporesponsiveness. This is achieved by stimulating donor cells with recipient APC while providing blockade of CD28-mediated co-stimulation signals.This "alloanergization" approach reduces alloreactivity by 1-2 logs while preserving pathogen- and tumor-associated antigen T cell responses in vitro. The strategy has been successfully employed in 2 completed and 1 ongoing clinical pilot studies in which alloanergized donor T cells were infused during or after HLA-mismatched HSCT resulting in rapid immune reconstitution, few infections and less severe acute and chronic GvHD than historical control recipients of unmanipulated HLA-mismatched transplantation. Here we describe our current protocol for the generation of peripheral blood mononuclear cells (PBMC) which have been alloanergized to HLA-mismatched unrelated stimulator PBMC. Alloanergization is achieved by allostimulation in the presence of monoclonal antibodies to the ligands B7.1 and B7.1 to block CD28-mediated costimulation. This technique does not require the production of specialized stimulator APC and is simple to perform, requiring only a single and relatively brief ex vivo incubation step. As such, the approach can be easily standardized for clinical use to generate donor T cells with reduced alloreactivity but retaining pathogen-specific immunity for adoptive transfer in the setting of AHSCT to improve immune reconstitution without excessive GvHD.
authors: Medical Oncology, Dana Farber Cancer Institute, USA.
authors: Jeff K
authors: JK
authors: Davies
authors: Christine M
authors: CM
authors: Barbon
authors: Annie R
authors: AR
authors: Voskertchian
authors: Lee M
authors: LM
authors: Nadler
authors: Eva C
authors: EC
authors: Guinan
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D018122:B7-1 Antigen / Q000276:immunology*; D051940:B7-2 Antigen / Q000276:immunology*; D017635:Clonal Anergy / Q000276:immunology; D018920:Coculture Techniques; D000939:Epitopes; D006680:HLA Antigens / Q000276:immunology; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007519:Isoantigens / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed
chemical_list: D000911:Antibodies, Monoclonal; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D000939:Epitopes; D006680:HLA Antigens; D007519:Isoantigens