Aim: Elevated levels of BAFF have been detected in serum and synovial fluid samples from patients with rheumatoid arthritis (RA), increased expression of BLyS results in the presence of anti-DNA antibodies, rheumatoid factor (RF), circulating immune complexes,which are the typical symptoms of RA.The objective of this study was to investigate the effect of BLyS and its receptors in different stages in rats with adjuvant-induced arthritis(AA).Methods: Histopathological changes of the spleen were observed by HE staining.The levels of BLyS, interferon (IFN)-γ, interleukin (IL)-1, tumor necrosis factor(TNF-α),transforming growth factor beta (TGF)-β1,IL-6and IgG, IgM, IgA were measured by enzyme-linked immunosorbent assay.The expression of BAFF, TACI, B-cell maturation antigen (BCMA) and B cell activating factor-receptor (BAFF-R) were investigated by q-PCR in spleen and Bone marrow dendritic cells(BMDC).The localization and expression of CD103 were investigated by immunohistochemistry in spleen.The expression of activation markers(CD80, CD86 and CD40 and MHC Ⅱ molecules) and endocytic capacity using flow cytometric analysis.Result: The levels ofBLyS, IL-6, TNF-α,IFN-γ were increased in serum and supernatant DC of AA rats from d7.BAFF, TACI and BCMA expression are increased in d7, BAFF-R expression is decreased from d7 to d28 in BMDC.However BAFF and BAFF-R expression are increased in d14, in spleen.CD80, CD86 and CD40 and MHC Ⅱ molecules were incressed obviously in BMDC from d7 and endocytic capacity of BMDC were decressed from d7.CD103 distributed distinctly increasing in white pulp,red pulp and marginal zone.Conclusion: BAFF levels are increased in both BMDC and spleen in early stage.BAFF play a crucial role in the progress of pathogenesis in AA, but in different cell may through different receptor signals.