Increased random movement of neutrophils
Increased adhesiveness to intima
Unidirectional locomotion of neutrophils
Chemotaxis is defined as a unidirectional movement of leukocytes up to a concentration gradient of chemotactic molecules. All granulocytes, monocytes and to a lesser extent lymphocytes respond to chemotactic stimuli with varying rates of speed.
Chemoattractants are exogenous or endogenous. Exogenous agents are bacterial products. Endogenous mediators are:
- Components of complement pathway C5a.
- Products of lipoxygenase pathway LTB4.
- Cytokines particularly those of chemokine families.