Schematic overview of the complement system. Boxes indicate specific complement activation products measured by enzyme-linked immunosorbent assay (ELISA) and their relation to specific complement activation pathways. C1rs-C1inh complexes reflect classical pathway activation, C4bc reflects both classical and lectin pathway activation, and C3bBbP reflects alternative pathway activation. C3bc and terminal complement complex (TCC) are activation products of the final common and terminal pathways. MBL indicates mannose-binding lectin; MASP, MBL-associated serine protease.