title: The cellular signature of urinary immune cells in Lupus nephritis: new insights into potential biomarkers.
abstract: BACKGROUND
  Urinary T cells represent a reliable noninvasive biomarker for proliferative Lupus nephritis (LN). Little is known about the presence of T cell subsets, B cells and macrophages in the urine although they may further improve the validity of urinary cellular biomarkers for LN.
  
  
  METHODS
  We analyzed contemporaneous blood and urine samples of patients with active LN (n = 19), other Systemic Lupus Erythematosus (SLE) patients (n = 79) and urine samples of patients with diabetic nephropathy (DN; n = 14) and anti-neutrophil cytoplasmatic antibody (ANCA) associated vasculitis (AAV; n = 11) by flow cytometry.
  
  
  RESULTS
  Numbers of urinary T cells, B cells and macrophages correlated with disease activity and were significantly higher in the active LN group. Urinary T cells showed excellent distinction of patients with active LN, CD8+ T cells (AUC of ROC = 1.000) and CD4+ T cells (AUC = 0.9969) alike. CD19+ B cells (AUC = 0.7823) and CD14+ macrophages (AUC = 0.9066), as well as the clinical standard proteinuria (AUC = 0.9201), failed to reach these high standards. Patients with DN or AAV also showed increased urinary cell counts, although the CD4/CD8-ratio was significantly lower in SLE compared to in DN (p = 0.0006). Urinary CD4+ T cells of active LN patients proved to be mainly of effector memory phenotype and expressed significantly more CD40L and ki67 than corresponding blood cells. Urinary Treg counts correlated with disease activity.
  
  
  CONCLUSIONS
  Despite of detectable urinary cell counts for B cells and macrophages, T cells remain the best urinary cellular biomarker for LN. A low CD4/CD8-ratio seems to be characteristic for LN.
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. katharina.kopetschke@charite.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Kopetschke
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. jan.klocke@charite.de.
authors.forename: Jan
authors.initials: J
authors.lastname: Klocke
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. anna-sophie.griessbach@charite.de.
authors.forename: Anna-Sophie
authors.initials: AS
authors.lastname: Grießbach
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. humrich@drfz.de.
authors.forename: Jens Y
authors.initials: JY
authors.lastname: Humrich
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. robert.biesen@charite.de.
authors.forename: Robert
authors.initials: R
authors.lastname: Biesen
authors.affiliation: Department of Rheumatology, Universitätsklinikum Schleswig-Holstein, Lübeck, Germany. duska.dragun@charite.de.
authors.forename: Duska
authors.initials: D
authors.lastname: Dragun
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. gerd.burmester@charite.de.
authors.forename: Gerd-Rüdiger
authors.initials: GR
authors.lastname: Burmester
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. Philipp.Enghard@Charite.de.|Department of Rheumatology, Universitätsklinikum Schleswig-Holstein, Lübeck, Germany. Philipp.Enghard@Charite.de.
authors.forename: Philipp
authors.initials: P
authors.lastname: Enghard
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. gabriela.riemekasten@charite.de.|Department of Rheumatology, Universitätsklinikum Schleswig-Holstein, Lübeck, Germany. gabriela.riemekasten@charite.de.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Riemekasten
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001402:B-Lymphocytes / Q000276:immunology*; D015415:Biomarkers / Q000652:urine; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008181:Lupus Nephritis / Q000175:diagnosis / Q000276:immunology* / Q000652:urine*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D015415:Biomarkers