Chemotaxis in response to activation of cells results in -
Random multidirectional movement
Unidirectional motion
Adhesion to endothelium
Augmeted oxygen dependent bactericidal effect
Ans. is 'b' i.e., Unidirection motion Chemotoxis After extravasation from the blood vessels, leukocytes emigrate in tissues towards the site of injury by chemotoxis. Chemotoxis is unidirectional locomotion oriented along a chemical gradient. o This chemical gradient is created by the substances called chemoattractants (chemotactic agents), which maybe:? I. Exogenous --> Bacterial products 2. Endogenous --> C5a, LTB4, IL-1, TNF, IL-8. Note : C5a is the most powerful chemoattractant. How does chemotactic agents induce chemotaxis ? o Chemotactic agents bind to G-protein coupled recepotors on the surface of leukocytes. o This results in activation of intracellular GTPases. o The GTPases induce polymirization of actin at the leading edge of the cell and reorganization at trailing edge. o Locomotion involves rapid assembly of actin. Remember o Phagocytosis also involves assembly of actin.