Introduction: We studied the association between Henoch-Schönlein purpura nephritis (HSPN) and complement system activation. Methods: We retrospectively reviewed the pathologic findings and medical records of 35 children and 12 adults with HSPN and compared the differences according to C4d positivity in three groups consisting of total 47 patients, 35 pediatric and 12 adult patients, respectively. C4d staining of renal biopsy was additionally performed at the time of diagnosis or retrospectively using archival biopsy material. Results: The overall rate of C4d positivity was 53.2%: 20 (57.1%) of the 35 children and five (41.7%) of the 12 adults. Among the groups there was no significant difference in the severity of proteinuria, renal function, presence of crescents or mesangial proliferation stratified by C4d positivity, unlike IgA nephropathy. Conclusions: We suggest that the activation of complement system is not correlated with the clinical or pathological severity of HSPN.
Keywords: C4d; Henoch-Schönlein purpura nephritis; IgA nephropathy; children; complement system.