Fig. 1.

Samples of five aHUS patients containing eculizumab showed a high degree of hemolysis in the alternative pathway (AP) hemolytic assay (a). No C5b-9 was formed in these samples in the AP Wieslab test (b). Moreover, no soluble C5b-9 (sC5b-9, c) was formed during in vitro activation of normal human serum control (NHS) with zymosan A when eculizumab was added; however, generation of the C3 activation product C3bBbP remained unaffected (d). In the AP hemolytic assay, the serum of C5-deficient donor showed lysis similar to that of NHS spiked with 500 µg/mL eculizumab (e). This lysis was suppressed in the presence of 40 µg/mL compstatin Cp40 (f). Rabbit erythrocytes pre-exposed to NHS spiked with 500 µg/mL eculizumab (g) or C5-deficient serum (h) under AP-permissive conditions showed high osmotic fragility, which was restored by the addition of Cp40