Main feature of chemotaxis is -

Ans. is 'd' i.e., Unidirectional locomotion of neutrophils When a host encounters an injurious agent, such as an infectious microbe or dead cells, phagocytes that reside in all tissues try to get rid of these agents.At the same time phagocytes and other host cells react to the presence of the foreign or abnormal substance by liberating cytokines/ chemokines and various other mediators of inflammation.Some of these mediators act on the endothelial cells in the vicinity and promote the efflux of plasma and the recruitment of circulating leucocytes to the site where the offending agent is located.Chemotaxis is recruitment of leucocytes at the site of injury. Leucocytes moves towards the site of injury because of the chemokines/cytokines present at the site of injury. Chemotaxis is defined as movement of leucocytes oriented along a chemical gradient