Abstract Background and Aims Complement is involved in numerous kidney diseases. However, functional approaches to properly examine individual's susceptibility to complement dysregulation are limited. Method We assessed ex vivo complement activation induced by sera from 38 healthy donors on resting microvascular endothelial cells (HMEC-1) with or without complement dysregulation by an anti-FH monoclonal antibody (OX-24 mAb). Following incubation, immunofluorescence was used to reveal and quantify membrane-bound C3c (evaluating C3b/iC3b) and C5b-9 with a computer-assisted method (H-score). Additionally, complement anaphylatoxins (C3a and C5a) were quantified in cell supernatants by ELISA. Further exploration of ex vivo complement activation profiles were conducted by next generation sequencing of a panel of alternative pathway genes in 32 donors. Results Increase in complement deposition on HMEC-1 surface was defined for a H-scoreC3c > 50 and/or a H-scoreC5b-9 > 30. Combined analysis of C3b/iC3b and C5b-9 deposition in 35 donors showed that one donor (2.8%) had an isolated increase in C3b/iC3b deposits, 3 (8.6%) had an isolated increase in C5b-9 deposits and one other (2.8%) had both increased C3b/iC3b and C5b-9 deposition. Genetic analysis of 32/38 donors revealed 3 heterozygous rare or low frequency missense variants in CFH (p.N1050Y and p.R1210C) and CFI (p.A76G) in 3/5 donors (60%) with increased complement deposition. Conclusion Our ex vivo model for measuring complement activation allowed the identification of distinct complement activation profiles among healthy donors, revealing genetic susceptibility in 3 donors. This new dynamic and functional model provides an exciting avenue for exploring the mechanisms governing complement dysregulation in various kidney diseases in research.