Immunity complexity: Controlling degree of response (Introduction)

by David Turell @, Friday, February 14, 2020, 01:01 (9 days ago) @ David Turell

Attack intensely or just a little. Immune cells make these decisions:

"Scientists and physicians have long known that immune cells migrate to the site of an infection, which individuals experience as inflammation -- swelling, redness and pain. Now, Northwestern University and University of Washington researchers have uncovered new evidence that this gathering is not just a consequence of immune activation. Immune cells count their neighbors before deciding whether or not the immune system should kick into high gear.


"The body's immune system is constantly working to maintain a delicate balance. When a threat is introduced, the system needs to respond strongly enough to fight off infection or disease but not so strongly that it causes harm.

"'When it comes to immune responses, it's the difference between life and death," Leonard said. "If your body over-responds to a bacterial infection, then you could die from septic shock. If your body doesn't respond enough, then you could die from rampant infection. Staying healthy requires the body to strike a balance between these extremes."


"To explore this phenomenon, the researchers examined macrophages, a type of immune cell that is part of the first line of defense for combatting infection and disease. They observed how macrophages responded to a chemical produced by bacteria -- a red flag that alerts the body to the presence of infection -- using techniques that enabled the researchers to watch individual cells' responses over time. They then used computational models to help interpret and explain these observations.

"'Over time, the cells observe their surroundings to get a sense of their neighbors," Muldoon said. "Each cell becomes poised to respond as a high activator or not. Now that we know there's this additional layer controlling the immune system, it opens up a whole avenue to study whether there are new targets for immunomodulation."


"'Biology has evolved so many fascinating and surprising ways to control complex processes," Leonard said."

Comment: Note the final entry. Of course there have to be controls: an out of control immune response could trigger severe autoimmunity and kill the host organism. Just as in blood clotting there are controlling feedback factors to produce just the right amount of activity. This is not a mechanism that can be developed by chance. It has to designed all At once to be perfect in its function or here will be death. Without accuratde feedback systems life could not exist. Design required.

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