C3a

C3a is a protein fragment produced when the complement system is activated. The complement system is a crucial part of the immune system, composed of over 30 proteins that work together to defend the body against infections.12

When the complement system is triggered, a chain reaction occurs, leading to the activation of a key protein called C3. This protein then splits into two fragments: C3a and C3b. C3a's primary role is to promote inflammation, helping to alert the immune system to an infection. C3b, on the other hand, binds to the surface of invading microorganisms, marking them for destruction by other immune cells or directly damaging them by forming membrane attack complexes.12