Immunity system complexity: T cells memory (Introduction)

by David Turell , Tuesday, April 14, 2020, 21:47 (1683 days ago) @ David Turell

A new study showing how they develop:

https://www.sciencedaily.com/releases/2020/04/200414122750.htm

"The discovery that immune T cells have a spectrum of responsiveness could shed light on how our immune system responds to infections and cancer, and what goes wrong in immune diseases. Researchers found that T cells responded very differently to immune signals the more 'training' they had been exposed to.

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"T cells are key white blood cells that fight infection and disease, and act like police directing the immune system response. Babies are born with inexperienced -- naïve -- T cells, which change as they come into contact with bacteria or viruses, to create specific memory T cells that can 'remember' fighting against these infections. These memory T cells can then react more quickly the next time they meet the same threat, telling the immune system to remove the infection rapidly. This is how vaccination protects against disease, by delivering a safe form of an invading virus or bacterium, to train our immune system by building up specific memory T cells.

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"The researchers discovered that instead of having a simple switch, from naïve to memory cell, there appeared to be a whole continuum of T cell development. They revealed that the more often a T cell had been activated by one signal, the further along the line of memory T cell development -- its 'training' -- it was, and the faster it could respond to that specific signal.

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" 'Previously people thought that memory T cells had two stages of development, but we discovered there is a whole spectrum of memory experience. From naïve T cells that have never been activated, to highly trained memory T cells which can react quickly, and many intermediate T cells in between. This spectrum not only affects how fast a cell can respond, but even what signals it can respond to."

"The study showed the T cells also had a continuum of responsiveness to other chemical signals, revealing they were less specialised than previously thought. They found that even highly trained memory T cells could be triggered by other, new immune signals.

"The researchers discovered that some signals created very different responses in memory cells, depending on their experience level. When a specific chemical signal (transforming growth factor -TGF) was added to naïve T cells, they responded by producing regulatory T cells to calm down the immune system. However, the same chemical had the opposite effect on experienced memory cells, triggering them to release more chemicals that cause inflammation."

Comment: Fighting infections is a lifelong battle. T cells are beautifully designed for the
battle, but not perfectly. They can overreact and cause autoimmune diseases.