The pro- or anti-inflammatory effector functions of IgG antibodies are regulated through their interactions with activating and inhibitory Fc receptors on target cells. Recent publications now show that these pro- or anti-inflammatory effects of IgG antibodies are also determined through the intrinsic glycosylation pattern of their Fc part. Sialylated IgGs show anti-inflammatory effects. In this project we want to investigate whether serum IgG antibodies present during an acute allergic response against birch pollen are different to those present after hypo-sensitization with birch pollen allergen Bet v 1 regarding glycosylation pattern and function.