In the synovial lining CD68, CD163 and HLA-DR were increased in SpA versus RA; in the sublining CD163 and HLA-DR were also increased. In contrast, costimulatory molecules and dendritic cell markers were scarce in SpA versus RA synovium. Interestingly, CD163 and CD68 were also increased in colonic lamina propria in SpA. CD163 and HLA-DR in the sublining were correlated with CRP and ESR. CD163+ macrophages expressed high levels of HLA-DR and could produce TNF-alpha but not IL-10. Anti-TNF-alpha therapy in SpA induced a decrease of CD163 in both synovial lining and sublining.