Quantitative Complement Levels in Renal Diseases
Abstract
Background Complement activation accompanies immune‐mediated kidney injury, but patterns of C3, C4, and properdin changes vary by disease. We evaluated these serum components in Turkish patients with chronic glomerulonephritis, amyloid nephritis, acute post-streptococcal GN, and chronic pyelonephritis compared to healthy controls.
Methods Fifty-five patients (27 chronic GN, 19 amyloid nephritis, 6 acute GN, 3 chronic pyelo-nephritis) and 13 controls had serum C3, C4, and properdin measured by single-radial immunodiffusion. Results were expressed in mg/dL and compared using t-tests.
Results Chronic GN patients showed normal C3 with significant C4 and properdin reductions (p<0.05), indicating classical and alternative pathway activation. Amyloid nephritis cases had elevated C4 (p<0.01) but normal C3 and properdin, suggesting isolated C4 activation. Acute GN exhibited marked C3 depletion (p<0.001) with normal C4 and properdin. Chronic pyelonephritis patients and controls had all components within normal ranges.
Conclusion Distinct complement profiles emerge in different renal diseases. C3 depletion is characteristic of acute post-streptococcal GN, C4 elevation of amyloid nephritis, and combined C4/properdin reductions of chronic GN. Quantitative C3, C4, and properdin assays can aid differential diagnosis and understanding of renal immunopathology.
Keywords
Complement C3, Complement C4, Properdin, Glomerulonephritis, Amyloidosis
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