Final answer:
Decay accelerating factors (DAFs) function as a form of enzyme regulation to protect cells from their own complement system, preventing unnecessary or harmful immune responses.
Step-by-step explanation:
The use of decay-accelerating factors (DAFs) by cells to protect themselves from complement is a form of enzyme regulation of its function. These decay-accelerating factors help in inhibiting the binding and activation of complement components, preventing the complement cascade and protecting host tissues from damage. The complement system is an array of proteins, including DAFs, which is involved in the immune response, functioning to destroy extracellular pathogens. Since DAFs are essential in managing and regulating the activity of the complement system, they prevent an excessive or inappropriate immune response against the cells of the organism itself.