How do neutrophils cause inflammation?

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Doing a college essay which is partly about bronchiectasis and am trying to explain the vicious circle of bronchiectasis. I think it’s important to speak about how the bodies own immune response also adds to this circle but I just need some help understanding HOW neutrophils cause inflammation like my books say? Thanks 🙂

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Neutrophils can amplify inflammation but are not the primary, igniting source of an inflammatory response – that’s would be something like a virus, bacteria, toxin, trauma, or stress.

Essentially, cells send out signals when the are damaged by infection or other cause mentioned above. Cells in the area then release **cytokines** that ramp up the inflammatory response. Each specific cytokine (ex: TNF-a, IL-1, IL-6, etc.) has a specific job. For example, some cytokine dilate blood vessels so that more blood (carrying the fighter cells like neutrophils) can come to the area of damage. Others make blood vessels “leaky” (AKA increase vascular permeability) so that the fluid carrying these response cells can leak out of the blood stream and into surrounding tissues. Combined, this is what causes the visible signs of inflammation such as swelling, redness, and heat that you’d see with an infected cut, for example.

Some inflammatory mediators (cytokines, chemokines) attract white blood cells (such as neutrophils) to the site of infection/inflammation/damage. **Neutrophils are the first white blood cells to report for duty in an acute inflammatory process**. They then start eating pathogens and eventually, kill themselves and the pathogens within them. This is a nonspecific response to infection, so this is the innate immune system. Neutrophils also release pro-inflammatory molecules (like cytokines) that recruit other kinds of cells to help fight the infection. One such cell type is macrophages, which then come in to continue the clean-up process and release factors that start the healing process.

In summary, it’s all a complicated network of inflammatory signals (certain signals pulling neutrophils in, then neutrophils releasing even more signals to continue the inflammatory response).

Probably more in depth than you need, but [this Osmosis video](https://www.osmosis.org/learn/Inflammation) animated the process I just described.

*It’s been a while since I studied immunology, so please feel free to correct me!*