How does abatacept really work in rheumatoid arthritis?

PURPOSE OF REVIEW: The purpose of this review is to summarize the current knowledge concerning the mechanisms of action of Abatacept in patients with rheumatoid arthritis.

RECENT FINDINGS: Abatacept (CTLA-4Ig) represents a soluble, recombinant, fully humanized fusion protein, comprising the extracellular domain of CTLA-4 and the Fc portion of IgG1. Abatacept binds to the costimulatory molecules CD80 and CD86 on antigen-presenting cells (APC), thereby blocking interaction with CD28 on T cells. In humans, Abatacept treatment was shown to be effective in patients with various autoinflammatory diseases including rheumatoid arthritis. Although the prevention of T-cell activation by interfering with signaling via CD28 still represents the main mechanism of action Abatacept acts on additional cell populations including regulatory T cells (Treg), monocytes/macrophages, osteoclasts, and B cells.

SUMMARY: Effects of Abatacept on other cell populations besides T cells have to be taken into account and might represent a valuable contribution to the therapeutic success.