Breakdown products of C3 and Factor B in hemolytic-uremic syndrome

Serum concentrations of Clq, C4, C3, and Factor B but not properdin were significantly decreased in patients with HUS compared to values in normal control subjects (p value < 0.01). Sera from 13 HUS patients obtained early after the onset of the disease showed breakdown products of Factor B (Ba, Bb) by immunoelectrophoresis; 12 of these sera showed C3 breakdown products (C3c, C3d). Sera from seven patients studied 1 month to 3 years later no longer demonstrated any breakdown products of Factor B or C3. These data suggest that the complement system is activated in HUS. The concept that immunological mechanisms play a major role in this disease is additionally supported by the occurrence of IgM, C3, and fibrin in glomeruli and renal vessels.