Host alloantigens (HLA)

Host alloantigens are genetically determined antigens, primarily the Human Leukocyte Antigens (HLA) or Major Histocompatibility Complex (MHC) molecules, found on the surface of host cells that differ between individuals of the same species. These molecules play a critical role in the immune system by presenting peptides to T-cells, allowing for the discrimination between self and non-self. In the context of clinical transplantation, host alloantigens are the primary targets of the immune response in graft-versus-host disease (GvHD), where donor T-cells recognize and attack the recipient's tissues. Conversely, in organ transplantation, donor alloantigens are recognized by the host's immune system, leading to graft rejection. While alloantigens themselves are not typically the direct binding targets of small molecule drugs, therapeutic strategies focus on suppressing the T-cell mediated immune response elicited by these antigens using calcineurin inhibitors, mTOR inhibitors, and various monoclonal antibodies.

Other names

Human leukocyte antigensMajor histocompatibility complex antigensMHC antigensAlloantigensTransplantation antigens

Drugs do not typically bind directly to host alloantigens; instead, they inhibit the T-cell activation, proliferation, or effector functions triggered by the recognition of these alloantigens by the recipient's or donor's immune system.