Bet v 1–specific immunoglobulin G and immunoglobulin G4 (Bet v 1-specific IgG/IgG4)

Bet v 1–specific IgG and IgG4 are protective antibodies produced by the immune system in response to the major birch pollen allergen, Bet v 1, particularly during allergen-specific immunotherapy (AIT). Bet v 1 is the primary driver of birch pollen allergy and associated oral allergy syndrome, where it cross-links IgE antibodies on mast cells and basophils to trigger mediator release. IgG4, in particular, serves as a 'blocking antibody' that competes with IgE for the same or overlapping epitopes on the Bet v 1 molecule (Subbarayal et al., 2013). By sequestering the allergen or sterically hindering its interaction with IgE, these antibodies prevent the activation of inflammatory cells and the resulting allergic symptoms. This mechanism is central to the development of clinical tolerance in allergic individuals. The induction of high titers of Bet v 1–specific IgG4 is a hallmark of successful desensitization and is used as a key biomarker for monitoring the clinical efficacy of AIT products like Itulazax and Alutard SQ (Kinaciyan et al., 2015). Furthermore, these antibodies are being investigated for use in passive immunotherapy to provide rapid, IgE-independent protection against birch pollen-induced allergic rhinitis and associated food allergies. Overall, these antibodies represent the body's adaptive mechanism for neutralizing allergens and restoring immune homeostasis.

Other names

Birch pollen-specific IgG4Bet v 1-specific blocking antibodiesAllergen-specific IgG4Bet v 1-specific IgG

Allergen-specific immunotherapy induces the production of Bet v 1-specific IgG4 antibodies, which act as 'blocking antibodies' by competing with IgE for allergen binding, thereby inhibiting mast cell degranulation and the subsequent allergic cascade (Subbarayal et al., 2013; Kinaciyan et al., 2015).