Final answer:
Positive acute phase proteins, such as C-reactive protein, mannose-binding lectin, and fibrinogen, play key roles in the body's early innate immune response. They help in opsonization, phagocytosis, and maintaining vascular integrity. Interferons are also critical early-induced proteins in combating viral infections.
Step-by-step explanation:
Some positive acute phase proteins serve as important factors in the body's innate immune response to inflammation and infection. These proteins include C-reactive protein (CRP), which is produced in the liver and binds to phosphocholine on the surface of dead or dying cells (and some types of bacteria), leading to their opsonization and enhanced phagocytosis. Other examples include mannose-binding lectin, which binds to mannose on pathogen surfaces and plays a role in opsonization as well, and fibrinogen, which aids in blood clot formation and supports vascular integrity during injury or infection.
Early-induced proteins like interferons are also significant in the immune response, particularly during viral infections. Although not typically present, they are produced rapidly by infected cells and help protect surrounding cells by inducing the production of antiviral proteins. The acute phase response also includes enhanced production of complement proteins that form part of the complement system, facilitating the destruction of pathogens.