title: Expression of P-glycoprotein in lymphocytes of children with nephrotic syndrome treated with glucocorticoids.
abstract: BACKGROUND
  Glucocorticoids are still the mainstay of therapy for nephrotic syndrome (NS) in children. Poor response to glucocorticoids may relate, in part, to the overexpression of P-glycoprotein (P-gp). The aim of the present study was to determine the expression of P-gp in lymphocytes (CD3) in the peripheral blood of children with steroid-sensitive nephrotic syndrome in the dynamics of the disease. The study group (I) consisted of 18 children, median age 5.75 years, with steroid-sensitive nephrotic syndrome, in whom the examinations were carried out three times: (A) before treatment, during relapse; (B) after 3-4 weeks of prednisone treatment; (C) 2 months after finishing prednisone treatment. The control group (II) consisted of 18 healthy children of the same age. P-gp expression in CD3 lymphocytes of peripheral blood was measured using flow cytometry. During NS relapse and prior to glucocorticoid administration, the CD3/P-gp level was higher (median 3.20%, range 0.80-7.80%) when compared to healthy controls (1.10%, range 0.30- 2.20%) (p<0.01). During glucocorticoid treatment, CD3/P-gp increased significantly and was much higher than in the control group (p<0.01) and in the NS children before treatment (p<0.01). In remission, the P-gp expression decreased, but did not achieve the values of the controls (p<0.05). Fourteen out of eighteen (14/18) children still showed P-gp values above the cut-off level. We also found a positive correlation between the P-gp expression and total prednisone dose in the NS children in all examinations: A: (r=0.540, p<0.05); B: (r=0.630, p<0.01); C: (r=0.653, p<0.01).
  
  
  CONCLUSIONS
  In conclusion, the overexpression of P-gp in remission, after finishing glucocorticoid treatment, may indicate that P-gp plays a role in the response to corticosteroids in nephrotic children.
authors.affiliation: 1st Department of Pediatrics, Medical University of Białystok, ul. Waszyngtona 17, 15-274 Białystok, Poland. annwasil@interia.pl
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wasilewska
authors.forename: Walentyna M
authors.initials: WM
authors.lastname: Zoch-Zwierz
authors.forename: Mirosława
authors.initials: M
authors.lastname: Pietruczuk
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000293:Adolescent; D017252:CD3 Complex; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D005260:Female; D005434:Flow Cytometry; D005938:Glucocorticoids / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D018655:Lymphocyte Count; D008297:Male; D009404:Nephrotic Syndrome / Q000188:drug therapy* / Q000378:metabolism; D011241:Prednisone / Q000494:pharmacology / Q000627:therapeutic use*; D012008:Recurrence; D012074:Remission Induction; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D017252:CD3 Complex; D005938:Glucocorticoids; D011241:Prednisone