The genes expressed similarly in bone marrow and SLE PC but not in tonsil PC include ADA, BCL6, MYC, LCK, SYK, ACAT1, S100A4, CAV1 and surface markers CD19,-22, -72, -79 and CD83. Notably, in SLE PC, expression of some genes did not match that expected from the bone marrow PC profile, including CXCR4, ITGA6 and PECAM1, which may reflect abnormal migration of SLE PC to tissue niches. Here, PECAM1 is linked to systemic lupus erythematosus.