Therefore, in patient cohort 1 we compared the following synovial features between the pooled SpA group (50 samples) and the RA group (52 patients): lining layer thickness, vascularity, global cellular infiltration, lymphoid follicles, plasma cells, PMCs, CD3, CD4, CD8, CD20, CD38, CD138, CD68, CD163, CD1a, CD83, CD146, αVβ3, E-selectin, ICAM-1, VCAM-1, intracellular citrullinated proteins and MHC–HC gp39 peptide complexes. Here, CD38 is linked to rheumatoid arthritis.