title: B cell attracting chemokine 1 (CXCL13) and its receptor CXCR5 are expressed in normal and aberrant gut associated lymphoid tissue.
abstract: OBJECTIVE
  In mice, the B lymphocyte chemoattractant (BLC) CXC chemokine ligand 13 (CXCL13) is sufficient to induce a series of events leading to the formation of organised lymphoid tissue. Its receptor, CXCR5, is required for normal development of secondary lymphoid tissue. However, the human counterpart, B cell attracting chemokine 1 (BCA-1) has only been detected in the stomach and appendix and not in other parts of normal or diseased gut. Hence to elucidate the potential role of this chemokine and its receptor in human gut associated lymphoid tissue (GALT), we analysed their expression in normal intestine and ulcerative colitis (UC).
  
  
  METHODS
  Frozen sections of surgical specimens were studied by multicolour immunofluorescence staining, in situ mRNA hybridisation, and reverse transcription-polymerase chain reaction.
  
  
  RESULTS
  BCA-1 mRNA was detected in all normal colonic and UC specimens. BCA-1 was produced and accumulated in relation to peripheral dendritic elements of lymphoid follicles in Peyer's patches and normal colon, as well as in irregular lymphoid aggregates in UC lesions. BCA-1 was partially associated with the traditional follicular dendritic cell phenotype but also with extracellular fibrils in GALT structures. CXCR5 protein was expressed by mantle zone B cells and appeared at a high level on scattered germinal centre T cells.
  
  
  CONCLUSIONS
  BCA-1 and CXCR5 are expressed in normal GALT structures as well as in irregular lymphoid aggregates in UC. This strongly suggests that BCA-1 plays an important role not only in the formation of normal GALT but also in the generation of aberrant lymphoid tissue in inflammatory bowel disease.
authors.affiliation: Laboratory for Immunohistochemistry and Immunopathology, Institute of Pathology, and Department of Surgery, University of Oslo, Rikshospitalet, Oslo, Norway. hege.carlsen@klinmed.uio.no
authors.forename: H S
authors.initials: HS
authors.lastname: Carlsen
authors.forename: E S
authors.initials: ES
authors.lastname: Baekkevold
authors.forename: F-E
authors.initials: FE
authors.lastname: Johansen
authors.forename: G
authors.initials: G
authors.lastname: Haraldsen
authors.forename: P
authors.initials: P
authors.lastname: Brandtzaeg
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000378:metabolism; D054382:Chemokine CXCL13; D019743:Chemokines, CXC / Q000378:metabolism*; D002648:Child; D003093:Colitis, Ulcerative / Q000276:immunology / Q000378:metabolism*; D003106:Colon / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D008875:Middle Aged; D010581:Peyer's Patches / Q000378:metabolism*; D010641:Phenotype; D054380:Receptors, CXCR5; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000378:metabolism
chemical_list: C110663:CXCL13 protein, human; C095085:CXCR5 protein, human; D054382:Chemokine CXCL13; D019743:Chemokines, CXC; D054380:Receptors, CXCR5; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine