The following is a summary of “Role of IgG1 and IgG4 as dominant IgE-blocking antibodies shifts during allergen immunotherapy,” published in the MAY 2023 issue of Allergy (& Immunology) by Strobl, et al.

Allergen immunotherapy (AIT) induces the production of allergen-specific IgE-blocking antibodies, with IgG4 traditionally considered the main inhibitory isotype. However, recent studies have indicated the early dominance of IgG1 in AIT. For a study, researchers sought to monitor the IgE-blocking activity and avidity of allergen-specific IgG1 and IgG4 antibodies throughout a 3-year AIT treatment.

Serum samples were collected from 24 patients before and at regular intervals during AIT for birch pollen. Bet v 1-specific IgG1 and IgG4 levels were measured using ELISA and ImmunoCAP. The inhibition of Bet v 1-induced basophil activation was compared between unmodified samples and samples depleted of IgG1 or IgG4. The stability of Bet v 1-antibody complexes was assessed using ELISA and surface plasmon resonance.

Bet v 1-specific IgG1 levels peaked at 12 months of AIT, while IgG4 levels peaked at 24 months. Serological IgE-blocking activity reached its highest point at 6 months and remained elevated throughout the treatment period. In the first year of therapy, the depletion of IgG1 significantly reduced the inhibition of basophil activation, while the absence of IgG4 had minimal impact on IgE blocking. However, over time, IgG4 became the main inhibitory isotype in most individuals. IgG1 and IgG4 exhibited high avidity for Bet v 1 from the start of AIT, with no significant increase during treatment. Bet v 1-IgG1 complexes were more stable than Bet v 1-IgG4 complexes.

Despite the constant avidity of AIT-induced allergen-specific IgG1 and IgG4 antibodies, their dominance in IgE-blocking activity shifted throughout treatment. The inhibitory role of allergen-specific IgG1 should not be underestimated, particularly in the early stages of AIT.

Source: jacionline.org/article/S0091-6749(23)00036-2/fulltext