C4 a

《英文msh词典》C4 a
[入口词] C4 a
[主题词] Complement 4a
[英文释义] Smaller fragment formed when C1s splits C4 into C4a and C4b. As an anaphylatoxin,C4a causes symptoms of immediate hypersensitivity but it has weaker activity than C3a or C5a.