Expression And Significance Of Interleukin-21 In Serum Of Children With Henoch-schonlein Purpura

Objective: To observe the changes of serum interleukin-21(IL-21)levels which is the major cytokine secreted by serum follicular helper T cells(TFH),and to investigate the role of IL-21 in the pathogenesis ofHenoch-Schonlein purpura(HSP)in children.We also aimed to find new targets for HSP treatment.Methods:A total of forty hospitalized children in Linyi Central Hospital with acute Henoch-Schonlein purpura from January 2017 to October 2017 were enrolled in this study.Twenty healthy children in outpatient examination were taken as normal control group.All the diagnoses of children with HSP were in accordance with the diagnostic criteria of Evidence-based diagnosis and treatment of Henoch-Schonlein purpura in October 2012.According to the recommendation of "diagnosis and treatment of Purple Palsy nephritis" in the Nephrology Group of the Chinese Academy of Pediatrics.The study group was divided into two groups: HSPN group(20 cases)and NHSPN group(20cases).At the same time,according to the history of infectious diseases(such as acute upper respiratory infection,acute tonsillitis,acute bronchitis,bronchopneumonia,etc.)within 2 weeks before the onset of the disease,40 cases of HSP were divided into two groups: infected HSP group(26 cases)and non-infected HSP group(14 cases).By statistical analysis,there was no significant difference in age and gender between each group(P >0.05).Venous blood samples were collected on an empty stomach in the morning.The serum was separated and stored in the refrigerator at-80 ?(for IL-21).The serum immunoglobulin IgG IgA and IgM were also tested at the same time.All subjects had no history of renal disease,allergic disease and other autoimmune diseases within 24 hours before blood collection.Serum IL-21 level detection was detected by double antibody sandwich ELISA.Immunoglobulin was detected by Turbidimetry in serum immunoglobulin.Results:The level of serum IL-21 in children with HSP was(1509.9 + 213.6)ng/L.It was significantly higher than that of the healthy control group(85 9.3 �95.9)ng/L(P < 0.001).The serum IL-21 level in HSPN group was 1535.3 �205.5 ng / L in acute phase.The serum IL-21 level in NHSPN group was 1484.6 �223.8ng / L in acute phase.There was no significant difference between the two groups(P > 0.05).But the serum IL-21 level in HSPN group and NHSPN group was significantly higher than that in healthy control group(P < 0.001).The serum IL-21 level of children with HSP infection in acute phase was(1515.9 �190.9)ng/L.The serum IL-21 level of children without HSP infection was(1503.9 �238.9)ng/L.There was no significant difference between the two groups(P > 0.05).However,the serum IL-21 level of both groups was significantly higher than that of healthy control group(P < 0.001).There was a significant positive correlation between serum IL-21 level and IgA level in children with HSP at acute stage(r= 0.838,P < 0.001).But there was no significant difference in IgA expression between HSPN group and NHSPN group(P > 0.05).Conclusion : Serum lL-21 level was significantly increased in children with Henoch-Schonlein purpura in acute phase.However,there was no significant difference in the expression of serum lL-21 between children with HSP without early renal damage and between children with HSP without preinfection.There was a significant positive correlation between serum lL-21 level and serum IgA level in children with acute Henoch-Schonlein purpura.The results suggested that the increased expression of lL-21 in Tfh cells may play an important role in the pathogenesis of HSP.But the relationship with Henoch-Schonlein purpura nephritis remains to be further studied.