CD30(+) T cells in rheumatoid synovitis: Mechanisms of recruitment and functional role

High serum levels of soluble CD30 (sCD30) have been reported to better pred ict the response to second line therapy in rheumatoid arthritis (RA). It is believed that sCD30 is released by CD30(+) T cells present in the RA synov ium, However, both the mechanism of recruitment to the joint and the functi onal role of this T. cell subset in the pathogenesis of the disease remain unknown. This study confirmed higher levels of sCD30 in the serum and synov ial fluid (SF) of RA patients compared with normal controls. However, analy sis of mRNA and cell surface CD30 expression showed that CD30(+) T cells ar e detectable in the SF, but not in the synovial membrane. In contrast, T ce lls expressing the CD30 transcript, but not the surface molecule, were foun d in the peripheral blood of both RA and normal controls. CD30 surface expr ession was up-regulated by adhesion and migration through endothelium in vi tro and in a delayed-type hypersensitivity model in vivo. Although the grea t majority of fresh or cloned CD30(+) T cells from SF produced both IFN-gam ma and IL-4, CD30 expression strictly correlated with IL-4 synthesis in syn ovial T cell clones. In addition, CD30(+) T cell clones also produced high amounts of the anti-inflammatory cytokine IL-10. On this basis, we would li ke to propose that synovial CD30(+) cells may play a role in the control of the inflammatory response. Serum sCD30 may reflect such cell activity and, therefore, explain the previously demonstrated correlation between high sC D30 serum levels and positive response to therapy.