In our in vitro study, the capability of CTLA4-Ig treatment to induce the upregulation of CD163 and MerTK gene expression, together with that of CD204 and CD206, in cultured RA-MDMs seems to promote the shift into an M2 macrophages phenotype which might have a role in the reduction of inflammation in RA patients. Here, MERTK is linked to rheumatoid arthritis.