Chemotaxis is mediated by?

Ans. is 'a' i.e., C5a o C5a is the most powerful chemo-attractant (chemokine).Chemotaxiso Chemotaxis is unidirectional locomotion of leukocytes towards the site of injury, oriented along a chemical gradient. This chemical gradient is created by substances called chemoattractants (chemotactic agents), which may be exogenous (bacterial products) or endogenous (C5a, LTB-4, IL-1, TNF, IL-8).