title: The role of CD8+ CD40L+ T cells in the formation of germinal centers in rheumatoid synovitis.
abstract: In rheumatoid synovitis, lymphocytes can be arranged in follicular structures resembling secondary lymphoid follicles. To understand the organizing principles of this ectopic lymphoid tissue, the cellular components contributing to synovial follicles were examined. In 9 of 24 synovial tissue biopsies, lymphoid aggregates were found consisting of CD4+ T cells and CD20+ B cells. In four of the nine patients, the follicular centers were occupied by CD23+ CD21+ cellular networks representing follicular dendritic cells involved in germinal center reactions. In five patients, CD23+ cells were absent from the centers of the aggregates, suggesting that fully developed germinal centers are generated in only a subset of patients. To identify factors involved in the regulation of the synovial microarchitecture, cell populations contributing to the follicles were quantified by digital image analysis of immunostained tissue and by flow cytometry of tissue-derived lymphocytes. Proportions of CD4+, CD20+, and CD68+ cell subsets were surprisingly invariant, irrespective of the presence or absence of CD23+ follicular dendritic cells. Instead, tissue biopsies with CD23+ germinal center-like regions could be distinguished from those with CD23- T cell-B cell aggregates by a fourfold increase in the frequency of tissue-infiltrating CD8+ T cells, a fraction of which expressed CD40 ligand (CD40L). The data suggest a previously unsuspected role of CD8+ lymphocytes in modulating germinal center formation and raise the possibility that CD8+ CD40L+ T cells are involved in aggravating pathologic immune responses in rheumatoid synovitis.
authors.affiliation: Department of Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
authors.forename: U G
authors.initials: UG
authors.lastname: Wagner
authors.forename: P J
authors.initials: PJ
authors.lastname: Kurtin
authors.forename: A
authors.initials: A
authors.lastname: Wahner
authors.forename: M
authors.initials: M
authors.lastname: Brackertz
authors.forename: D J
authors.initials: DJ
authors.lastname: Berry
authors.forename: J J
authors.initials: JJ
authors.lastname: Goronzy
authors.forename: C M
authors.initials: CM
authors.lastname: Weyand
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000473:pathology; D019013:CD40 Antigens / Q000502:physiology*; D023201:CD40 Ligand; D016827:CD8 Antigens / Q000502:physiology*; D018414:CD8-Positive T-Lymphocytes / Q000473:pathology; D002465:Cell Movement / Q000276:immunology; D005260:Female; D018858:Germinal Center / Q000473:pathology*; D006801:Humans; D008024:Ligands; D018655:Lymphocyte Count; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000502:physiology*; D008875:Middle Aged; D013583:Synovial Membrane / Q000737:chemistry / Q000276:immunology / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D019013:CD40 Antigens; D016827:CD8 Antigens; D008024:Ligands; D008562:Membrane Glycoproteins; D023201:CD40 Ligand