The serum complement system: a simplified laboratory exercise to measure the activity of an important component of the immune system.

The immune system is a vital physiological component that affords animals protection from disease and is composed of innate and adaptive mechanisms that rely on cellular and dissolved components. The serum complement system is a series of dissolved proteins that protect against a variety of pathogens. The activity of complement in serum can be determined by its ability to lyse red blood cells in vitro.