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Brief introduction into immunology (Background reading) - The innate immune system

4 important questions on Brief introduction into immunology (Background reading) - The innate immune system

What is the mechanism of a phagocyte?

All phagocytic cells have receptors on their surfaces, like mannose receptor, complement receptor etc. That stimulate the phagocytosis of microbes. These receptors attach to the surface proteins of specific pathogens, which also induce the release of cytokines that communicate with the leukocytes. The bound pathogen is engulfed and destroyed via oxidative mechanisms in the phagocyte and finally degraded. Portions of the digested pathogen will then be presented to components of the adaptive immune system.

Phagocytosis has 2 major roles:

Destruction of the pathogen and the simultaneous secretion of messenger molecules that trigger supportive responses such as inflammation, Messenger cells

can have local effect, due to chemotaxis and attraction of many phagocytic cells
may also induce increased permeability permitting leukocytes to have greater access to the area as well as natural killer (NK) cells

2. Induction of the adaptive immune response via antigen-presentation

Serum amyloid A and C-reactive protein (CRP) can have a rise in the blood as much as 2000x within hours after injury or infection. This fast response is regulated by:

Cytokines, like IL-1, IL-6 and TNF-alpha secreted by phagocytes.

What are Toll-Like Receptors (TLR)?

Transmembrane proteins with a long extracellular part and an intracellular part responsible for signal transition finally resulting in the activation of NF-kB. This nuclear factor (NF) plays an important role in the induction of immune and inflammatory reactions.