University of Central Florida (UCF) PCB3233 Immunology Practice Exam 1

The primary function of C5a in the immune response involves its role as a potent chemotactic factor. C5a is one of the anaphylatoxins generated during the activation of the complement system, specifically from the cleavage of complement component C5. Once formed, C5a plays a crucial role in the immune response by helping to recruit neutrophils and other immune cells to the site of infection or inflammation.

Neutrophils are essential components of the innate immune system. When C5a is produced, it binds to specific receptors on the surface of neutrophils, leading to their activation and migration toward the area where C5a is present. This migration is vital for the effective clearance of pathogens. Neutrophils help eliminate invading microbes directly through phagocytosis and also release reactive oxygen species and other mediators that contribute to the inflammatory response.

Understanding the action of C5a emphasizes its importance in acute inflammatory responses—facilitating the quick recruitment of immune cells to manage infections. This process can significantly enhance the body's ability to respond to potentially harmful pathogens in a timely manner.