title: Hereditary polycystic kidney disease is characterized by lymphopenia across all stages of kidney dysfunction: an observational study.
abstract: Polycystic kidney disease (PKD) is characterized by urinary tract infections and extrarenal abnormalities such as an increased risk of cancer. As mutations in polycystin-1 and -2 are associated with decreased proliferation of immortalized lymphoblastoid cells in PKD, we investigated whether lymphopenia could be an unrecognized trait of PKD.
  
  
  
  We studied 700 kidney transplant recipients with (n = 126) or without PKD at the time of kidney transplantation between 1 January 2003 and 31 December 2014 at Ghent University Hospital. We also studied 204 patients with chronic kidney disease (CKD) with PKD and 204 matched CKD patients without PKD across comparable CKD strata with assessment between 1 January 1999 and 1 February 2016 at three renal outpatient clinics. We compared lymphocyte counts with multiple linear regression analysis to adjust for potential confounders. We analysed flow cytometric immunophenotyping data and other haematological parameters.
  
  
  
  Lymphocyte counts were 264/µL [95% confidence interval (CI) 144-384] and 345/µL (95% CI 245-445) (both P < 0.001) lower in the end-stage kidney disease (ESKD) and CKD cohort, respectively, after adjustment for age, sex, ln(C-reactive protein) and estimated glomerular filtration rate (in the CKD cohort only). In particular, CD8+ T and B lymphocytes were significantly lower in transplant recipients with versus without PKD (P < 0.001 for both). Thrombocyte and monocyte counts were lower in patients with versus without PKD in both cohorts (P < 0.001 for all analyses except P = 0.01 for monocytes in the ESKD cohort).
  
  
  
  PKD is characterized by distinct cytopenias and especially lymphopenia, independent of kidney function. This finding has the potential to alter our therapeutic approach to patients with PKD.
authors.affiliation: Renal Division, Ghent University Hospital, Ghent, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Van Laecke
authors.affiliation: Department of Haematology and Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University Hospital, Ghent, Belgium.
authors.forename: Tessa
authors.initials: T
authors.lastname: Kerre
authors.affiliation: Renal Division, Ghent University Hospital, Ghent, Belgium.
authors.forename: Evi V
authors.initials: EV
authors.lastname: Nagler
authors.affiliation: Department of Nephrology, AZ Delta, Roeselare, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Maes
authors.affiliation: Division of Nephrology, OLVZ, Aalst, Belgium.
authors.forename: Rogier
authors.initials: R
authors.lastname: Caluwe
authors.affiliation: Renal Division, Ghent University Hospital, Ghent, Belgium.
authors.forename: Eva
authors.initials: E
authors.lastname: Schepers
authors.affiliation: Renal Division, Ghent University Hospital, Ghent, Belgium.
authors.forename: Griet
authors.initials: G
authors.lastname: Glorieux
authors.affiliation: Renal Division, Ghent University Hospital, Ghent, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Van Biesen
authors.affiliation: Renal Division, Ghent University Hospital, Ghent, Belgium.
authors.forename: Francis
authors.initials: F
authors.lastname: Verbeke
mesh_terms: D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000150:complications*; D008231:Lymphopenia / Q000150:complications*; D008297:Male; D008875:Middle Aged; D007690:Polycystic Kidney Diseases / Q000209:etiology* / Q000473:pathology*; D011379:Prognosis