Fig. 4

Macrophages are present in the lining- and sub-lining layer of the synovial membrane and co-localize with IL-10 and TNF mRNA. a–c Representative images of a patient 1, b patient 3, and c patient 8. Even if we could not detect an increased expression of CD163 in synovial fluid monocytes, it is clearly present in tissue monocytes/macrophages. Antibodies to CD14 and CD68 were also tested and provided similar staining, but CD163 provided the most specific staining. Monocytes and macrophages are found extensively in both the lining and sub-lining region of the synovial membrane. In situ hybridization targeting IL-10 (red dots) and TNF (blue dots) mRNA was performed in subsequent sections. Both TNF and IL-10 are found in areas that are dense in macrophage numbers. Staining for polarization markers revealed both single and co-expression of CD40 and CD206 in macrophages, as well as in other cell types as neither CD40 nor CD206 is specific for monocytes/macrophages. Individual channel images are found in grayscale in supplementary Fig. 7. Scale bar in 10x: 220 μm and in 20×: 100 μm. For immunofluorescence: 50 μm