In the complement system, which is not true?
A. C3a, C5a cause vasodilation, and increased vascular permeability.
B. C5a is a powerful chemotactic agent.
C. C5a activates the cyclo-oxygenase pathway of arachidonic acid metabolism.
D. C5 can be activated by kallikrein.
E. C3b, C3bi can act as op
C. C5a activates the cyclo-oxygenase pathway of arachidonic acid metabolism.
C5a is a potent chemotactic factor and anaphylatoxin that can increase vascular permeability and cause vasodilation, but it does not directly activate the cyclo-oxygenase pathway. The cyclo-oxygenase pathway is involved in the production of prostaglandins and is not directly activated by complement components.