MHC class II–Amb a 1 peptide complex (MHC II–Amb a 1 complex)

The MHC class II–Amb a 1 peptide complex is a molecular assembly formed by the presentation of short ragweed (Ambrosia artemisiifolia) major allergen (Amb a 1) fragments on the surface of antigen-presenting cells (APCs) via Major Histocompatibility Complex class II (MHC II) molecules. Amb a 1 is a pectate lyase and the primary driver of ragweed allergy, with over 95% of ragweed-sensitive individuals exhibiting IgE reactivity to it (NIH, 2016). The complex is specifically recognized by the T cell receptors (TCRs) of CD4+ T lymphocytes, triggering a Th2-polarized immune response characterized by the production of cytokines like IL-4, IL-5, and IL-13, which promote IgE synthesis and eosinophilic inflammation (Jahn-Schmid et al., 2010). This interaction is the fundamental step in the pathogenesis of ragweed-induced allergic rhinitis and asthma. Therapeutically, this complex is targeted by allergen-specific immunotherapy (AIT) and peptide-based vaccines designed to induce peripheral T cell tolerance or immune deviation toward a Th1 or regulatory T cell (Treg) phenotype (Frontiers in Immunology, 2024). Such treatments aim to desensitize the immune system, reducing the allergic symptoms upon subsequent exposure to ragweed pollen.

Other names

HLA-DR–Amb a 1 complexHLA-DQ–Amb a 1 complexHLA-DP–Amb a 1 complexRagweed allergen-MHC II complexpMHC complex (Amb a 1)Amb a 1-MHC II complex

Allergen-specific immunotherapy (AIT) involves the administration of the allergen or its peptides to induce immunological tolerance, shifting the T cell response from a pro-allergic Th2 profile to a Th1 or regulatory T cell (Treg) profile, thereby reducing IgE-mediated inflammation.