Clinical value of B-cell-activating factor receptor in childhood idiopathic thrombocytopenic purpura

Background: B cells play a key role in the pathogenesis of autoimmune diseases by secreting autoantibodies, presenting antigens, and secreting cytokines. Activation of autoreactive B cells is largely mediated by a cytokine called B-cell-activating factor (BAFF), which mediates its signal mainly through BAFF-R. The present study aimed to clarify the impact of BAFF/BAFF-R dysregulation on disease activity and response to therapy in childhood thrombocytopenic purpura (ITP). Materials and methods: Forty-three patients (23 acute and 20 chronic ITP) and 20 age-matched and sex-matched healthy controls were enrolled in this study. Serum BAFF was determined using the enzyme-linked immunosorbent assay technique and the expression of BAFF-R on CD19+ B cells was detected by flow cytometry. Results: In serum, BAFF level and BAFF-R expression were significantly higher in both acute and chronic ITP patients than in the controls (P⩽0.001). No significant difference was found in the BAFF level and BAFF-R expression between acute and chronic ITP (P=0.456 and 0.124, respectively). After treatment with immunosuppressive therapy, BAFF level and BAFF-R expression were significantly decreased in acute ITP compared with levels before treatment (P⩽0.001). No significant difference was found in the serum BAFF level, whereas BAFF-R expression was significantly higher in active ITP than inactive ITP (P=0.544 and 0.015, respectively). Conclusion: Our data suggest that BAFF-R is more relevant than serum BAFF as an activity biomarker in ITP patients. It will be interesting to assess the possible implications of this upregulation of BAFF-R on BAFF-targeted therapy in ITP patients, especially those with active disease.