A link between B cell receptor expression and autoantibody production in rheumatoid arthritis
By now, it is a well known fact, that B cells play an important role in the development of autoimmunity. On the one hand, they are the precursors of the antibody-secreting plasmablasts and memory cells; on the other hand they also act as antigen-presenting cells.
Various cells of the immune system express a plethora of receptors that bind to the
Fc-portion of immune complexes containing IgG (Fc-gamma-receptors, FcγR), but
B cells and plasma cells only express the low affinity FcγRIIb. This receptor has repressive functions and mediates the deletion of autoreactive B cells and the inhibition of IgG secretion, thereby helping to preserve B cell tolerance.
Human autoimmune diseases that are characterized by an abnormal production of autoreactive antibodies have been suspected to come along with impaired FcγRIIb function. Alterations of the expression of FcγRIIb on B cells have been shown for Lupus erythematosus and several other autoimmune diseases, but until now, data have been lacking for rheumatoid arthritis. (more…)