title: [Expression of IL-21 in the peripheral blood of myasthenia gravis patients and its correlation with anti-AChR-Ab class switch].
abstract: OBJECTIVE
  To explore the role of IL-21 in the pathogenesis of myasthenia gravis (MG) and its influence on the the class switch of anti-AChR antibodies.
  
  
  METHODS
  Blood was taken from 26 patients and 18 healthy controls, and the expression of IL-21R mRNA in peripheral blood mononuclear cells (PBMCs) was detected by RT-PCR. The expression of IL-21R on B lymphocytes was measured by flow cytometry, while the concentrations of serum IL-21 and the levels of anti-AChR-IgG and its isotype IgG(1), IgG(2), and IgG(3) were tested by ELISA.
  
  
  RESULTS
  The serum concentration of IL-21 in the MG group was higher than that in the control group (31.686±8.499 pg/mL, 15.147±6.366 pg/mL) and the difference was significant (P<0.01). IL-21R mRNA expressed on PBMCs in the MG group was higher than that in the control group (0.139±0.052, 0.101±0.022), and the difference was significant (P<0.05). There was no difference between ocular MG and generalized MG subgroup (P>0.05). Compared with the control group, the expression of IL-21R on B lymphocytes also increased in the MG group (P<0.05). In the anti-AChR-Ab positive MG group, the serum concentration of IL-21 showed positive correlation with anti-AChR-IgG(P<0.05),but no correlation with its isotype IgG(1), IgG(2), and IgG(3), respectively(P>0.05). Expression of IL-21R mRNA in the PBMCs showed no correlation with the level of serum anti-AChR-IgG and its isotype IgG(1), IgG(2), and IgG(3), respectively(P>0.05); however the expression of IL-21R in B lymphocytes showed positive correlation with anti-AChR-IgG and it's isotype IgG(1) and IgG(3) (P<0.05,P<0.01,P<0.05), but no correlation with IgG(2) (P>0.05).
  
  
  CONCLUSIONS
  IL-21 might induce the class switch of anti-AChR antibodies to IgG(1) and IgG(3) isotype through IL-21R on B lymphocytes which promotes the pathogenesis of the MG.
authors.affiliation: Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Tian
authors.forename: Huifen
authors.initials: H
authors.lastname: Huang
authors.forename: Ai
authors.initials: A
authors.lastname: Jian
authors.forename: Song
authors.initials: S
authors.lastname: Ouyang
authors.forename: Weifan
authors.initials: W
authors.lastname: Yin
authors.forename: Weiwei
authors.initials: W
authors.lastname: Duan
authors.forename: Huan
authors.initials: H
authors.lastname: Yang
mesh_terms: D000293:Adolescent; D000328:Adult; D001323:Autoantibodies / Q000145:classification / Q000276:immunology*; D005260:Female; D006801:Humans; D017578:Immunoglobulin Class Switching / Q000276:immunology*; D007074:Immunoglobulin G / Q000145:classification; D007378:Interleukins / Q000097:blood* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000097:blood / Q000276:immunology*; D012333:RNA, Messenger / Q000097:blood / Q000235:genetics; D011950:Receptors, Cholinergic / Q000276:immunology*; D053655:Receptors, Interleukin-21 / Q000097:blood / Q000235:genetics; D055815:Young Adult; D000098546:Interleukin-21
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G; D007378:Interleukins; D012333:RNA, Messenger; D011950:Receptors, Cholinergic; D053655:Receptors, Interleukin-21; D000098546:Interleukin-21