As previously shown, the number of CD68+ macrophages in the intimal lining layer and synovial sublining was similar between the two diseases (Figure 1A, D), whereas CD163 expression was higher in the SpA compared with the RA intimal lining layer (P < 0.05) (Figure 1B), but similar in the synovial sublining (Figure 1E). This evidence concerns the gene CD68 and rheumatoid arthritis.