SELP and rheumatoid arthritis: TNF-α plays an important role in the recruitment of other leukocytes to RA synovial tissue [29], and this most likely pertains to the recruitment of pDCs to RA but not normal synovial tissue through expression of adhesion molecules such as intercellular adhesion molecule (ICAM)-1, CD62-E, and CD62-P and interaction with their ligands on pDCs [9,11,51-54].