Peptide–Human Leukocyte Antigen class II complex (pHLA-II)

Peptide–Human Leukocyte Antigen (HLA) class II complexes are molecular assemblies consisting of an HLA class II heterodimer (alpha and beta chains) and a bound antigenic peptide, typically 13–25 amino acids in length [Source: Janeway's Immunobiology]. These complexes are primarily displayed on the surface of professional antigen-presenting cells (APCs) such as dendritic cells, B cells, and macrophages to be recognized by the T-cell receptors (TCRs) of CD4+ T helper cells [Source: Nature Reviews Immunology]. This recognition is a cornerstone of the adaptive immune response, governing the activation of B cells for antibody production and the regulation of inflammatory responses. In many autoimmune diseases, such as Type 1 Diabetes and Rheumatoid Arthritis, specific HLA class II alleles present self-peptides that trigger an inappropriate immune attack against the body's own tissues [Source: NEJM]. Conversely, in oncology, the presentation of tumor-specific neoantigens by HLA class II molecules is vital for generating effective anti-tumor immunity and is a major focus for neoantigen vaccine development [Source: Science]. Therapeutic interventions targeting these complexes include peptide-based vaccines aimed at inducing immune tolerance or activation, as well as engineered TCR-like antibodies and CAR-T cells designed to recognize specific pHLA-II signatures on diseased cells [Source: Frontiers in Immunology].

Other names

pMHCIIMHC class II-peptide complexHLA class II-peptide complexAntigen-HLA class II complexHLA-DR/DQ/DP-peptide complex

Therapeutic strategies involve the use of specific peptides to occupy the HLA binding groove to induce immune tolerance in autoimmunity, or the use of TCR-like molecules and vaccines to trigger CD4+ T-cell mediated destruction of cells presenting specific disease-associated or tumor-derived peptides [Source: Nature Reviews Immunology, Frontiers in Immunology].