Alt a 1

Alt a 1 is the major allergen protein of the fungus Alternaria alternata. It is an acidic, heat-stable homodimeric protein with a molecular weight of approximately 30 kDa and consists of two monomers (16.4 and 15.3 kDa). Structurally, it features an unusual β-barrel fold unique to fungi[2][1]. Alt a 1 is highly immunogenic and responsible for most IgE-mediated allergic reactions in individuals sensitized to A. alternata; up to 80–95% of asthmatic or allergic rhinitis patients sensitized to A. alternata show IgE reactivity to this protein[2]. Mechanistically, Alt a 1 induces strong innate immune responses in bronchial epithelial cells by activating toll-like receptor pathways (notably TLR4), leading to secretion of cytokines such as IL-8, IL-33, and IL-25[6][5][2]. In animal models and clinical studies, recombinant or purified Alt a 1 has been used as the active ingredient in allergen-specific immunotherapy (AIT) for asthma and allergic rhinitis caused by Alternaria exposure; these therapies can reduce symptoms and medication use while modulating immune cell populations involved in allergy (e.g., T follicular helper cells decrease; regulatory B cells increase)[3][4]. Alt a 1 has limited cross-reactivity with other allergens but shares some structural similarity with human siderocalin proteins[2]. Its biological function within fungi remains unclear but may involve ligand transport or spore germination.

Brand names

Alt a 1 MOL

Other names

Alternaria alternata major allergenm229m-229m 229rAlt a 1