Activation of Complement System in Henoch-Schönlein Purpura Nephritis.

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.

The Transition from Thin Basement Membranes to Typical Alport Syndrome Morphology in Children.

Some children with thin basement membranes (TBM) turn out to have Alport syndrome (AS). In our population of 58 children initially diagnosed with TBM, three were eventually diagnosed with AS. As a group, these three were first biopsied at a younger age, and had gross rather than microscopic hematuria. Only one had lamellations initially. Seven others had some degree of basement membrane lamellations at initial biopsy, but none of these have developed other features of AS. We concluded that at least 5% of children initially demonstrating TBM go on to manifest the classical electron-microscopic findings of AS during childhood. Episodes of gross hematuria with TBM can be a significant clue of AS. Genetic and/or immunofluorescent studies for type IV collagen, and continued long-term follow-up should be done in all children with TBM.