Complement C4a

**Definition:** The smaller fragment formed when complement C4 is cleaved by COMPLEMENT C1S. It is an anaphylatoxin that causes symptoms of immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE) but its activity is weaker than that of COMPLEMENT C3A or COMPLEMENT C5A.

**Tree numbers:** - D12.776.124.486.274.024.260 - D12.776.124.486.274.350.250

**Synonyms:** - Complement Component 4a - C4a Complement - Complement 4a