Polymorphonuclear neutrophils
Polymorphonuclear neutrophils are cells of innate immunity because they do not have a specific antigen receptor, and they can exercise their effector functions without having encountered the antigen (they do not require priming).
Haematopoiesis / cytology
Polymorphonuclear neutrophils originate in the myeloid contingent. As their name implies, they have a polylobed nucleus (classically 2 to 5 lobes) with a cytoplasm that is poorly coloured by the May-Grunwald-Giemsa stain. They represent 50 to 70% of circulating leukocytes.
Functions
Antigen internalisation
Polymorphonuclear neutrophils have the capacity for diapedesis in addition to being the most numerous in the circulating blood, which leads to a great capacity to be relocalised in the tissues. Once in the tissues, neutrophils will notably have an antigen internalisation activity (endocytosis) thanks to three mechanisms:
Cytokine production
Polymorphonuclear neutrophils can release into their environment the contents of their granules including cytokines, particularly chemotactic ones.
What should be remembered
Polymorphonuclear neutrophils participate in the immune reaction as part of innate immunity. They have the particularity of being able to perform diapedesis, that is to say, pass through an endothelial wall to relocate from the blood compartment to the tissues. They are the first cellular actors recruited to the site of inflammation, particularly in the context of transplantation, where they can both internalise the antigen and recruit other immune effectors.
