Autoantibodies are considered to be major players in the pathogenesis of various autoimmune diseases. Although the antigenic target is usually known, both the mechanism by which autoantibodies are generated and the mechanism by which they contribute to disease pathogenesis are frequently unknown. Moreover, autoimmune diseases are different from infectious diseases because of the continuous presence of the antigen that can cause persistent stimulation of the autoreactive immune response.

In rheumatoid arthritis, autoantibodies to citrullinated antigens are considered to be involved in disease pathogenesis, although also here, the underlying mechanisms are incompletely understood. Antibodies are glycoproteins, with glycans attached to both the Fc part and the Fab portion. These glycans modulate the way by which antibodies interact with both the respective autoantigen and specific receptors on the surface of immune cells. In fact, variations in glycan structures can determine whether an antibody initiates or inhibits inflammatory responses. Based on these considerations, we have studied the glycosylation of IgG anti-citrullinated protein antibodies (IgG-ACPA) in detail and observed specific glycosylation patterns in both the Fc part and the Fab portion. In part, these glycosylation patterns are acquired shortly before disease onset. These studies give insight into potential interactions between IgG-ACPA and Fcγ-receptors as well as cell surface lectins. The presentation will cover the above mentioned aspects and provide data on ACPA-specific glycosylation patterns.

Disclosure of Interest None Declared