Serum from healthy carriers of complement gene mutations induces C3 and C5b-9 deposition on ADP-activated microvascular endothelial cells (HMEC-1). (A-B) Endothelial surface area covered by C3 (A) or C5b-9 (B) staining after incubation of ADP-activated HMEC-1 for 4 hr with serum (diluted 1:2 in test medium) from aHUS patients (C3 deposits: n = 6, 4 with CFH mutations, 1 with C3 mutation, and 1 with CFI mutation; C5b-9 deposits: n = 7, 4 with CFH mutations, 1 with C3 mutation, 1 with CFI mutation, and 1 with CFHR1/CFH hybrid gene) or from their healthy relatives carrying the same mutations (C3 deposits: n = 5, 3 with CFH mutation, 1 with C3 mutation, and 1 with CFI mutation; C5b-9 deposits: n = 6, 3 with CFH mutation, 1 with C3 mutation, 1 with CFI mutation, and 1 with CFHR1/CFH hybrid gene) in the presence or not of the complement inhibitor sCR1 (150 μg/mL) or from 7 healthy relatives without mutations (C5b-9 deposits). Control serum range: dotted horizontal areas. Data are mean ± SE. °P < .001, °°P < .01, vs control serum; *P < .001, **P < .01 vs aHUS patients without sCR1; §P < .001 vs mutation carriers without sCR1; #P < .01 vs carrier; &P < .001, &&P < .01 vs no carrier. (C) Data of plasma SC5b-9 levels and serum-induced C3 and C5b-9 deposition on ADP-activated HMEC-1 in unaffected relatives carrying complement gene mutations (healthy mutation carrier, n = 7) and unaffected relatives without mutations (only C5b-9, healthy no carrier, n = 7). °Limits of normal ranges (as defined in supplemental “Methods”). *P < .05 vs control serum (statistical comparisons were made for each relative by comparing deposits in pixel2 recorded in 15 fields analyzed for the relative and for the corresponding control run in parallel, as detailed in supplemental “Methods”). £: Serum-induced C3 or C5b-9 deposits on ADP-activated HMEC-1. mut, mutation; n.a., not available; n.d., not done.
