Characterization of factors influencing on-chip complement activation to optimize parallel measurement of antibody and complement proteins on antigen microarrays

► Complement C3 deposition can mask array-bound IgG molecules from being detected. ► Modest dilution of blood delivers reliable data on IgG binding and C activation. ► Concentrations of bivalent cations need strict control for reproducible data. ► Properdin initiated AP activation is not suitable for normalizing C3 deposition. ► IgG capturing from serum can serve as reference protein for normalization.