Background: This study aims to evaluate the immunological features of gastrointestinal (GI) bleeding in children with Henoch-Schönlein purpura (HSP).
Study Design: This retrospective study was conducted on children with HSP. Demographic and clinical data were collected, including serum immunoglobulin (Ig) levels, complement C3 and C4 levels, and lymphocyte subtype percentage.
Results: A total of 446 hospitalized children had HSP. Eighty-six children with HSP had GI bleeding, 114 had proteinuria, and 107 had hematuria. Lower arthralgia, prolonged glucocorticoid use, increased white blood cell counts, elevated neutrophils and neutrophil-to-lymphocyte ratio, reduced IgG and C3 levels, elevated CD19⁺ cell percentage, and reduced CD3⁺ cell and natural killer cell percentages were associated with GI bleeding risk in patients with HSP. Multivariate regression analysis revealed that arthralgia, glucocorticoid use, increased neutrophil percentage, reduced IgG and C3 levels, and increased CD19⁺ cell percentage were independent predictors of GI bleeding. Further analysis indicated that the combination of C3 and CD19⁺ cell percentages had a high predictive ability for GI bleeding in children with HSP.
Conclusion: This study indicated that reduced C3 and increased CD19⁺ cell percentages contributed to the development of GI bleeding in children with HSP. Specific immunologic profiles may be strongly correlated with GI bleeding risk in children with HSP.

Keywords: children, complement, gastrointestinal bleeding, Henoch-Schönlein purpura, lymphocyte subtype