Aberrant expression of BAFF in T cells of systemic lupus erythematosus, which is recapitulated by a human T cell line, Loucy.
B cell-activating factor of the tumor necrosis factor (TNF) family, or BAFF, is mainly produced in monocytes and dendritic cells, and indispensable for proliferation, differentiation and survival of B cells. BAFF is a type II membrane-bound protein and the extracellular C-terminal fragment is released from the cells as soluble BAFF (sBAFF), which binds to specific receptors on B cells. Accumulating evidence suggests that BAFF plays an important role in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE). In this study, we developed a sensitive sandwich ELISA system to quantify the amount of sBAFF using our own mAb. Treatment of peripheral T cells of SLE patients with an anti-CD3 antibody triggered robust expression of BAFF and subsequent release of sBAFF from the cells. On the other hand, the stimulus induced only marginal elevation of sBAFF from normal T cells. These data indicate that BAFF is expressed in T cells upon stimulation at least under pathological conditions. Expression of BAFF was also largely induced in a human T cell line, Loucy (American Type Tissue Collection CRL-2629), in response to several stimuli, while other T cell lines so far examined produced the cytokine almost constitutively. These data suggest that Loucy recapitulates some of the characteristics of SLE T cells. Investigation of molecular and cellular mechanisms of production of BAFF in Loucy demonstrated that expression of BAFF was regulated through a signal transduction pathway which involves c-jun NH2-terminal kinase and p38, and that shedding of BAFF was catalyzed by a membrane-bound protease, furin.
Yoshimoto
Keiko
K
Division of Rheumatology and Clinical Immunology, Saitama Medical Center, Saitama Medical University, Kawagoe, Saitama 350-8550, Japan. keiyoshi@sc.itc.keio.ac.jp
Takahashi
Yasue
Y
Ogasawara
Mie
M
Setoyama
Yumiko
Y
Suzuki
Katsuya
K
Tsuzaka
Kensei
K
Abe
Tohru
T
Takeuchi
Tsutomu
T
D053264:B-Cell Activating Factor; D002460:Cell Line; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D045683:Furin / Q000276:immunology / Q000378:metabolism; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000276:immunology / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000276:immunology* / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis / Q000276:immunology*; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000276:immunology*
D053264:B-Cell Activating Factor; D008565:Membrane Proteins; C505719:TNFSF13B protein, human; D014409:Tumor Necrosis Factor-alpha; D048031:JNK Mitogen-Activated Protein Kinases; D045683:Furin