Anti-IgE IgG provides better protection against allergen challenges than anti-IgE(PNG) IgG
Given that anti-IgE IgG antibodies can regulate serum IgE levels and basophil sensitization, we investigated their ability to protect mice from allergen challenges after IgE passive sensitization. We first investigated whether passive immunization with anti-IgE IgG, anti-IgE(PNG) IgG or a control IgG prior to IgE sensitization can protect against the Fel d 1 challenge (Fig. 3A). Mice receiving anti-IgE IgG were protected from the Fel d 1 challenge, whereas this was not the case for mice immunized with the control IgG (Fig. 3B). Immunization of mice with anti-IgE IgG (PNG) also conferred protection compared to the control group. However, comparing the area under (AUC) (drop of body temperature over time) of all three groups shows that anti-IgE IgG antibodies are significantly better in protecting mice from Fel d 1 challenge compared to anti-IgE(PNG) IgG antibodies (Fig. 3C).
To ensure that not any residual anti-Fel d 1 IgG antibodies mediate the protection of the anti-IgE IgG antibodies, the same experiment was performed with Ara R as an allergen (Fig. 3D). The results showed the same protection as when Fel d 1 was used as allergen indicating that anti-IgE IgG antibodies confer protection. Anti-IgE IgG and anti-IgE(PNG) IgG could significantly better protect mice from the Ara R challenge than the control IgG. However, again, anti-IgE IgG was more protective than anti-IgE(PNG) IgG (Fig. 3E and 3F).
These results suggest that anti-IgE IgG antibodies mediate the protection from allergen-challenge by active immunization of IgE-Fel d 1 complexes. Furthermore, they indicate that IgE glycosylation impacts the formation of IgG antibodies, which are efficient in protecting mice from allergen challenges.