C5b-9 deposition by flow cytometry on PIGA-null TF-1 cells. (A) Loss of CD59 expression on PIGA null TF-1 cells vs wild type TF-1 cells. (B) Comparison of C5b-9 deposition between aHUS and TTP samples and their heat-inactivated controls (HaHUS and HTTP, respectively). (C) Representative experiment of C5b-9 deposition after incubation with acute TTP serum (black) vs heat-inactivated control (light gray). (D) C5b-9 deposition after incubation with serum from a patient with aHUS in remission (black) compared with heat-inactivated control (light gray). (E) C5b-9 deposition after incubation with serum from a second patient with acute aHUS (black) compared with heat-inactivated control (light gray). HaHUS, heat-inactivated atypical hemolytic uremic syndrome serum; HTTP, heat-inactivated thrombotic thrombocytopenic purpura; MFI, mean fluorescence intensity.