Beta-expansin 1 (EXPB1)

Beta-expansin 1 (EXPB1) is a non-enzymatic plant protein that facilitates the loosening of plant cell walls by disrupting hydrogen bonds between cellulose microfibrils and matrix polysaccharides, particularly xylans in grasses (UniProt, Wikipedia). In clinical medicine, EXPB1 is recognized as the Group 1 grass pollen allergen, a major driver of seasonal allergic rhinitis and asthma affecting millions of individuals worldwide (PubMed, PMID: 10851476). These proteins are highly abundant in grass pollen and are essential for plant reproduction, as they allow the pollen tube to penetrate the stigma and style by softening the cell wall structure (PubMed, PMID: 11337410). As a therapeutic target, EXPB1 is the primary active component in allergen-specific immunotherapy (AIT) products, such as Grazax and Oralair, which are used to desensitize patients to grass pollen (FDA, Drugs.com). By administering controlled doses of EXPB1, clinicians can induce immunological tolerance, characterized by a shift from a Th2-mediated allergic response to a regulatory T-cell (Treg) and Th1-mediated response, thereby providing long-term relief from allergic symptoms (Journal of Allergy and Clinical Immunology). Safety concerns during treatment primarily involve the risk of systemic allergic reactions and anaphylaxis, necessitating careful patient monitoring during the initiation of therapy (StatPearls).

Other names

EXPB1Group 1 grass pollen allergenPhl p 1Zea m 1Cyn d 1Dac g 1Beta-expansin-1Pollen allergen Phl p 1Plant cell wall polysaccharides via β-Expansin 1

Allergen-specific immunotherapy (AIT) induces immune tolerance by shifting the immune response from a Th2-mediated allergic profile to a Th1 and regulatory T-cell (Treg) profile, leading to the production of blocking antibodies like IgG4.