The
terminal complement complex (TCC) has been reported to play an important role in the pathogenesis of
proteinuria not only in experimental
nephritis but also in human
glomerulonephritis. In order to clarify the clinical significance of TCC, the author investigated a total of 129 pediatric patients with the following glomerular diseases: idiopathic
nephrotic syndrome (INS; 40 cases),
IgA nephropathy (IgAN; 48 cases), mesangio-capillary
glomerulonephritis (MPGN; 16 cases),
lupus nephritis (LN; 16 cases),
purpura nephritis (5 cases) and membranous
nephritis (4 cases). Results were analyzed in relation to the responsiveness to
steroid treatment in INS and the degree of
proteinuria and histopathologic severity in glonerulonephritis groups. In 40 patients who underwent renal biopsy, the localizations of
vitronectin and
clusterin, both of which are regulatory
proteins for TCC, were examined by immunofluorescence microscopy in conjunction with that of TCC for the study of the mechanism of local defense in
glomerulonephritis. The urinary TCC levels were elevated in 9 (90%) of 10 patients with
steroid-resistant INS, while they were elevated only in 2 of 30
steroid-responsive patients. In
glomerulonephritis groups, urinary TCC levels were elevated in 13 of 48 patients with IgAN, 6 of 16 with MPGN, 8 of 16 with LN, 2 of 5 purpural
nephritis and 1 of 4 with membranous
nephritis. Urinary TCC levels correlated with histological severity in IgAN and showed a reciprocal relation to C3 levels in MPGN and LN. Immunofluorescence findings showed that localization of TCC was quite similar to that of C3 in
glomerulonephritis groups.
Vitronectin and
clusterin were also demonstrated to deposit in similar pattern to TCC. These results suggest that in INS urinary TCC levels could predict the responsiveness to
steroid therapy and might be useful as a non-invasive diagnostic method in differential diagnosis of INS. In IgAN, urinary TCC could be a useful marker of histologic severity. The deposition of
vitronectin and
clusterin together with TCC in glomerulus suggests the possibility that
vitronectin and
clusterin play a role in reducing the formation of TCC in glomerular tissues.