CTLA4 and rheumatoid arthritis: However, because macrophages play a crucial role in various steps of the synovial RA pathophysiology, the aim of this in vitro study was firstly, to search for the presence of the B7.2 molecule on the surface of cultured synovial macrophages (SM) obtained from active RA patients, and then to investigate the modulatory effects of CTLA-4-Ig in a co-culture of RA SM or macrophages together with an activated T cell line [21].