Recipient alloantigens

Recipient alloantigens are a diverse group of molecules, primarily including Major Histocompatibility Complex (MHC) proteins—known as Human Leukocyte Antigens (HLA) in humans—and minor histocompatibility antigens (mHAg), that differ between a transplant donor and recipient (Justiz Vaillant et al., 2024). In the context of allogeneic hematopoietic stem cell transplantation, these antigens are expressed on the recipient's host tissues and are recognized as foreign by the donor's mature T cells, triggering the complex immune response known as Graft-versus-Host Disease (GvHD) (Zeiser & Blazar, 2017). While not a single therapeutic target in the classical pharmacological sense, the recognition of these antigens is the fundamental driver of alloreactivity and transplant rejection (Shlomchik, 2007). Therapeutic strategies do not typically bind the alloantigens directly but instead focus on inhibiting the resulting T-cell activation and effector functions using immunosuppressants like calcineurin inhibitors or costimulation blockers like Abatacept (Zeiser & Blazar, 2017). Precise HLA matching between donor and recipient is the primary clinical method used to minimize the impact of these alloantigens and improve transplant outcomes (Goulmy, 2004). Consequently, the term refers to a broad category of immunological targets rather than a specific, individual protein or receptor.

Other names

Host alloantigensMinor histocompatibility antigens (mHAg)Major histocompatibility complex (MHC) antigensHuman leukocyte antigens (HLA)Allogeneic antigens

Inhibition of T-cell activation, costimulation blockade, and suppression of the immune cascade initiated by the recognition of non-self antigens.