Effect of Antigen Valency on Autoreactive B-Cell Targeting

Many autoimmune diseases are characterized by B cells that mistakenly recognize autoantigens and produce antibodies toward self-proteins. Current therapies aim to suppress the immune system, which is associated with adverse effects. An attractive and more specific approach is to target the autoreactive B cells selectively through their unique B-cell receptor (BCR) using an autoantigen coupled to an effector molecule able to modulate the B-cell activity. The cellular response upon antigen binding, such as receptor internalization, impacts the choice of effector molecule. In this study, we systematically investigated how a panel of well-defined mono-, di-, tetra-, and octavalent peptide antigens affects the binding, activation, and internalization of the BCR. To test our constructs, we used a B-cell line expressing a BCR against citrullinated antigens, the main autoimmune epitope in rheumatoid arthritis. We found that the dimeric antigen construct has superior targeting properties compared to those of its monomeric and multimeric counterparts, indicating that it can serve as a basis for future antigen-specific targeting studies for the treatment of RA.