Complement Component C5 is a protein that plays a crucial role in the immune system's complement pathway. It is part of the complement system, which helps the body fight infections and clear damaged cells. When activated, C5 is cleaved into two fragments, C5a and C5b, each with distinct functions in immune responses. C5a acts as a powerful inflammatory mediator, attracting immune cells to sites of infection or injury. In contrast, C5b initiates the formation of the membrane attack complex, which can directly destroy pathogens. Dysregulation of C5 can lead to various diseases, highlighting its importance in maintaining immune balance.