title: Participation of B-cell-activating factor receptors in the pathogenesis of immune thrombocytopenia.
abstract: ESSENTIALS: Dysfunctional B-cell-activating factor (BAFF) system is related to many autoimmune diseases. The regulatory functions of BAFF/BAFF receptors were investigated in an in vitro coculture system. Different regulatory roles of BAFF were investigated via different receptors in immune thrombocytopenia. The upregulated BAFF receptors on autoreactive lymphocytes lead to their hypersensitivity to BAFF.
  
  
  CONCLUSIONS
  
  
  
  BACKGROUND
  The pathogenesis of immune thrombocytopenia (ITP) remains enigmatic. B-cell-activating factor (BAFF) and its receptors (BAFF receptor [BAFF-R], transmembrane activator and calcium modulator and cyclophilin ligand interactor [TACI], and B-cell maturation antigen) play central roles in the integrated homeostatic regulation of lymphocytes.
  
  
  OBJECTIVE
  To investigate the pathologic roles of BAFF receptors in regulating the bioactivities of lymphocytes in ITP.
  
  
  METHODS
  An in vitro culture system was established by stimulating CD14(-) peripheral lymphocytes with platelet-preloaded dendritic cells in the presence of recombinant human BAFF (rhBAFF; 20 ng mL(-1)). The functions of BAFF receptors were specifically blocked with blocking antibodies.
  
  
  RESULTS
  BAFF-R, besides prolonging the survival of B cells in both patients and healthy controls, prominently promoted the survival of CD8(+) T cells and the proliferation of B cells in patients with ITP. TACI, as a positive regulator, not only promoted the proliferation of CD4(+) and CD8(+) T cells, but also significantly enhanced the secretion of interleukin-4 in patients with ITP, but not in controls. Besides revealing the pathologic roles of BAFF receptors, these results also indicate that lymphocytes of patients with ITP have enhanced antiapoptotic or proliferative capacity as compared with those from healthy controls when exposed under similar stimulation of rhBAFF. Further study demonstrated that activated autoreactive B cells and CD4(+) T cells from patients with ITP showed significantly higher expression of BAFF-R or TACI than those from healthy controls.
  
  
  CONCLUSIONS
  Both BAFF-R and TACI are pathogenic participants in ITP. Their dysregulated expression in patients with ITP may lead to hyperreactivity of activated autoreactive lymphocytes in response to rhBAFF, and thus is highly significant in the pathogenesis of ITP.
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: Y-N
authors.initials: YN
authors.lastname: Min
authors.affiliation: Department of General Medicine, Second Hospital of Shandong University, Jinan, Shandong, China.
authors.forename: C-Y
authors.initials: CY
authors.lastname: Wang
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: X-X
authors.initials: XX
authors.lastname: Li
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: J-H
authors.initials: JH
authors.lastname: Qiu
authors.affiliation: Department of General Medicine, Medical Research Institute for Tumor Prevention and Cure, Shandong University, Jinan, Shandong, China.
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: L-L
authors.initials: LL
authors.lastname: Shao
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: Y-W
authors.initials: YW
authors.lastname: Wang
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.|Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Jinan, Shandong, China.
authors.forename: J
authors.initials: J
authors.lastname: Peng
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.|Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Jinan, Shandong, China.
authors.forename: M
authors.initials: M
authors.lastname: Hou
authors.affiliation: Hematology Oncology Center, Qilu Hospital, Shandong University, Jinan, Shandong, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Shi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017209:Apoptosis; D053264:B-Cell Activating Factor / Q000494:pharmacology; D053265:B-Cell Activation Factor Receptor / Q000819:agonists / Q000276:immunology / Q000378:metabolism*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D001792:Blood Platelets / Q000276:immunology / Q000378:metabolism*; D016022:Case-Control Studies; D049109:Cell Proliferation; D002478:Cells, Cultured; D002908:Chronic Disease; D018920:Coculture Techniques; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D053303:Transmembrane Activator and CAML Interactor Protein / Q000494:pharmacology; D055815:Young Adult
chemical_list: D053264:B-Cell Activating Factor; D053265:B-Cell Activation Factor Receptor; D016207:Cytokines; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; C108467:TNFRSF13B protein, human; C435926:TNFRSF13C protein, human; C505719:TNFSF13B protein, human; D053303:Transmembrane Activator and CAML Interactor Protein
keywords: B-Cell activation factor receptor; B-cell maturation antigen; B-cell-activating factor; immune thrombocytopenia; immunomodulation; transmembrane Activator and CAML Interactor Protein