title: Elevated serum levels of interleukin 21 are associated with disease severity in patients with psoriasis.
abstract: BACKGROUND
  Psoriasis is an immune disorder involving numerous cytokines. Recent studies have shown that interleukin (IL)-21 plays an important role in a variety of inflammatory and autoimmune diseases. It is highly expressed in psoriatic plaques and promotes the proliferation of epidermis in mice. It seems that IL-21 plays an important role in the pathogenesis of psoriasis. However, whether or not it is elevated in the peripheral blood of patients with psoriasis and is associated with disease severity is unclear. Therefore, our study focuses on serum IL-21 levels and their correlation with disease severity.
  
  
  OBJECTIVE
  To detect serum IL-21 levels in patients with psoriasis and investigate the correlation between these and the Psoriasis Area and Severity Index (PASI) scores.
  
  
  METHODS
  Blood samples were collected from patients with plaque psoriasis and from healthy control subjects. Serum IL-21 levels were measured by enzyme-linked immunosorbent assay in 37 patients with psoriasis and 37 healthy controls. The PASI scores of patients with psoriasis and their correlation with serum IL-21 levels were evaluated.
  
  
  RESULTS
  Serum IL-21 levels were higher in patients with psoriasis than in healthy controls (P < 0·01). Serum IL-21 levels were positively correlated with PASI scores in the patients with psoriasis (r = 0·471, P < 0·01).
  
  
  CONCLUSIONS
  Serum IL-21 levels in patients with psoriasis are elevated and positively correlate with PASI scores. These results indicate that IL-21 may play an important role in the pathogenesis of psoriasis.
authors.affiliation: Department of Dermatology, Xijing Hospital, Fourth Military Medical University, 127 Changlexi Road, Xi'an 710032, China.
authors.forename: Z
authors.initials: Z
authors.lastname: He
authors.forename: L
authors.initials: L
authors.lastname: Jin
authors.forename: Z-F
authors.initials: ZF
authors.lastname: Liu
authors.forename: L
authors.initials: L
authors.lastname: Hu
authors.forename: E-L
authors.initials: EL
authors.lastname: Dang
authors.forename: Z-Z
authors.initials: ZZ
authors.lastname: Feng
authors.forename: Q-J
authors.initials: QJ
authors.lastname: Li
authors.forename: G
authors.initials: G
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007378:Interleukins / Q000097:blood*; D008297:Male; D011565:Psoriasis / Q000097:blood* / Q000473:pathology; D012720:Severity of Illness Index; D055815:Young Adult; D000098546:Interleukin-21
chemical_list: D007378:Interleukins; D000098546:Interleukin-21