Human leukocyte antigen (HLA) alloantigen (HLA)

Human leukocyte antigen (HLA) alloantigens are a group of highly polymorphic cell surface glycoproteins encoded by the Major Histocompatibility Complex (MHC) on chromosome 6 (StatPearls, 2023). They play a critical role in the immune system by presenting processed peptide fragments to T-cells, thereby facilitating the discrimination between self and non-self (NIH, 2022). HLA Class I molecules (HLA-A, -B, -C) are expressed on all nucleated cells and present antigens to CD8+ cytotoxic T-cells, while HLA Class II molecules (HLA-DR, -DQ, -DP) are primarily found on professional antigen-presenting cells and present to CD4+ helper T-cells (UniProt, 2024). In clinical medicine, HLA alloantigens are the primary barriers to successful organ and hematopoietic stem cell transplantation, as mismatching between donor and recipient can trigger potent immune responses leading to graft rejection or graft-versus-host disease (GVHD) (PubMed, 2021). Therapeutic strategies often involve broad immunosuppression using calcineurin inhibitors like tacrolimus to dampen the T-cell response against these alloantigens or desensitization protocols using agents like imlifidase to remove pre-existing anti-HLA antibodies (DrugBank, 2024). Additionally, specific HLA alleles are strongly associated with susceptibility to various autoimmune disorders and severe adverse drug reactions, such as Stevens-Johnson syndrome (NCBI, 2023).

Other names

Major histocompatibility complex antigensMHC antigensTransplantation antigensHuman leukocyte antigensHLA complex

Inhibition of T-cell signal transduction following HLA-peptide recognition, enzymatic cleavage of anti-HLA antibodies, or depletion of immune cells that respond to or produce antibodies against non-self HLA molecules.