F8 and rheumatoid arthritis: In the synovial tissue of our patient cohort, we measured the expression of CD68, a macrophage marker, given the clinical correlations found in RA; FVIII, an endothelial cell marker, due to the hypervascularity and vessel tortuosity evident in inflammed PsA synovium compared to that of RA [13-16]; and CD3, a T-cell marker.