Normal and PNH red blood cell (RBC) lysis by 1–12 fold dilutions of normal and PNH serum.

<p>Serum complement was activated by zymosan. Note that PNH serum, which contained eculizumab, was less active than normal serum. However addition of C5 protein at a final concentration of 100 µg/ml increased PNH RBC lysis to the same levels as control RBCs. Most importantly, ATA at a concentration of 1.67 µM completely blocked PNH RBC lysis. Values are mean±SEM, n = 4. Significance of differences was tested by two-way ANOVA. Multiple comparisons were followed with <i>post-hoc</i> Bonferroni tests where appropriate. The significance was p<0.01 for PNH patient serum with C5 added compared with PNH patient serum without C5 added, and p<0.01 for PNH patient serum with and without C5 compared with PNH patient serum plus ATA.