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.