Allogeneic peptide–Human Leukocyte Antigen complexes (pHLA complexes)

Host allogeneic peptide–Human Leukocyte Antigen (HLA) complexes are molecular assemblies consisting of a host-derived peptide bound to an HLA molecule that is recognized as foreign (allogeneic) by a recipient's or donor's immune system (Source: NIH, 2014). These complexes are the primary targets of alloreactive T cells, which recognize the combination of the non-self HLA structure and the presented peptide (Source: Frontiers in Immunology, 2021). In the context of allogeneic hematopoietic stem cell transplantation, donor T cells recognize host pHLA complexes, leading to the systemic inflammatory condition known as Graft-versus-Host Disease (GvHD) (Source: Frontiers in Immunology, 2021). Conversely, in solid organ transplantation, the recipient's T cells recognize donor pHLA complexes, resulting in graft rejection (Source: NIH, 2014). The interaction between the T-cell receptor (TCR) and the pHLA complex provides the primary signal for T-cell activation, which is often accompanied by costimulatory signals (Source: Frontiers in Immunology, 2021). Therapeutic strategies targeting this axis include costimulation blockers like abatacept and belatacept, which prevent the secondary signals required for full T-cell activation (Source: Frontiers in Immunology, 2021). Other treatments include broad immunosuppressants like cyclosporine and tacrolimus, which inhibit downstream signaling, or T-cell depleting agents like anti-thymocyte globulin (Source: NIH, 2014). Furthermore, specific allogeneic pHLA complexes are being utilized as targets for "allo-restricted" T-cell therapies in oncology, where high-avidity T-cell receptors are engineered to recognize tumor-specific peptides presented on allogeneic HLA molecules, bypassing the limitations of self-tolerance (Source: AACR, 2011). This target class is central to the fields of transplantation immunology and advanced cellular immunotherapy (Source: Frontiers in Immunology, 2023).

Other names

Host allogeneic peptide–HLA complexesAllogeneic MHC-peptide complexesHost pHLA complexesAllo-antigen complexesAllogeneic HLA-peptide complexes

Costimulation blockade, T-cell depletion, Inhibition of T-cell signaling, JAK/STAT inhibition, TCR-mediated cell killing