Abrogation of TT30 inhibition of hemolysis and dose-response curve at different hematocrits; PNH patients not on eculizumab. (A) Abrogation of TT30 effect by the blocking anti-CR2 mAb 1048 and comparison with human recombinant fH. Absolute percentage lysis of PNH RBCs in aNHS with and without TT30 ± the blocking anti-CR2 mAb 1048, or with the human recombinant fH (1μM), the human fH SCR1-5 (fH portion of TT30, 1μM) or the human CR2 SCR1-4 (CR2 portion of TT30, 1μM). Histograms represent the mean values of 6 experiments (4 in duplicate) on RBCs obtained from 4 untreated PNH patients; error bars represent SEM. (B) dose-response curve of TT30 on hemolysis at different hematocrits. Lysis (y-axis) of PNH RBCs according to TT30 concentration (x-axis); lysis is expressed as relative percentage of the lysis observed without any inhibitor (in each experiment, 100% represent the lysis observed in aNHS). Curves represent the mean of 14 experiments performed on samples obtained from 7 PNH patients (1 was drawn 4 times, 1 drawn 3 times, and 2 drawn twice), at different percentage of hematocrits. The continuous black line indicates hematocrit 2%; continuous gray line, hematocrit 16%; and dashed black line, hematocrit 33%. Error bars represent SEM.