Complement activity in plasma is hardly affected by C1-INH treatment. (A-D) Complement activation as measured by C4b/c and C3b/c detection in EDTA plasma by ELISA. (A) C4b/c levels at baseline do not differ between patients with AIHA and HCs. (B) C4b/c is at low levels, similar to HCs, throughout the trial. (C-D) C3b/c levels at baseline are all significantly increased compared with HCs and are reduced significantly at t = 36 hours only. (E) C3 levels are at the lower end of normal values (red area). (F-G) C4 and C2 levels are below normal values (red area) at most timepoints, indicating high consumption of C2 and C4. Data expressed as median + IQR. Significance was tested using the Mann-Whitney test (A,C), Wilcoxon matched-pairs signed rank test (B,D), and mixed-effects analysis with Geisser-Greenhouse correction (E-G). ∗P ≤ .05, ∗∗P ≤ .01, ∗∗∗P ≤ .001.