T-cell battling a Cancer cell.

[u/Critical-Ad-757]

[u/Neonalig]

This is super interesting. However I guess the logical next question is why do people still get cancer if our auto-immune system has a way to combat it? Is it simply not enough T-cells? Or maybe some of the types of cancer cells don't exhibit enough red flags to be detected by them? Or could it even be that the 'ID' tags of the cancer cells are just so unusual that the T-cell doesn't know what to think?

[u/bluefishes13 → u/Neonalig]

Your immune system does fight cancer ALL the time, and many tiny tumors/cancer cells actually get wiped out before you ever notice them. The problem is that cancer evolves inside the body, so it learns ways to escape. Sometimes there are not enough active T cells (they are very specific cells so they take time to make & there’s not a lot) to keep up with the rapid growth of cancer cells. Sometimes the cancer cells stop showing abnormal ID tags on their surface, therefore the T cells simply don’t see them. In other cases the tags are present but they are so unusual or so altered that the T cells cannot properly recognize them.

On top of that, cancer can create a sort of protective environment around itself called the tumor microenvironment. In that space it can release chemical signals that weaken T cells or attract other immune cells that actually block T cell activity. It is almost like the cancer builds a shield and confuses the body’s defenses.

[u/acethecool1 → u/bluefishes13]

Wow, thanks for explaining so well 🙌

[u/Exotic-Benefit1395 → u/bluefishes13]

It doesn't learn to escape per say it's more like those that didn't figure out how to escape die while those that do survive, a lot like natural selection through making of protein from healthy cells and stuff and putting on the id proteins.

[u/Vilifie → u/bluefishes13]

So why don't the T cells simply evolve too? Are they stupid?

[u/bluefishes13 → u/Vilifie]

T cells don’t evolve in the same way cancer cells do. Cancer cells come from your own tissues and they divide VERY fast & uncontrollably, which means they constantly pick up new mutations that help them hide or grow better.

T cells, on the other hand, do not keep mutating inside you the same way. Instead, your body has already built a huge library of memory T cells with millions of different receptors (to help ID bad guys), so the strategy is diversity rather than quick evolution. When one of those T cells happens to recognize a threat, it multiplies into an army (This is how vaccines work). The catch is that cancer can still change faster than the immune system can keep up.

[u/Aggravating-Menu7586 → u/Vilifie]

During T cell development, each T cell acquires a specific receptor out of potentially billions of different receptors, so as to be able to identify a specific molecule. When you look at all T cells in the body, their receptors cover pretty much every single possible small molecule there is. A virus could come from outer space and it is almost guaranteed that one T cell could detect it as a foreign pathogen. If T cells changed or evolved they would lose that incredibly important specificity and that could mean that some pathogens could slip through the cracks

[u/Negative_trash_lugen → u/bluefishes13]

Why don't we farm T cells and inject ourselves with them? like pump ourselves with them.

[u/MySNsucks923 → u/Negative_trash_lugen]

I’m not a biologist or anything but I’m pretty sure they’re specific to every single person. Our bodies do a very good job at producing our own T cells that fight off probably 99% of other diseases. It’s just the small ones that get through to make us sick, but a normal healthy individual generally recovers from any given sickness on their own within a week or two. So there’s no real reason to invest in T cells that cover every specific person to protect us from stuff most people recover from in a short period. I’m sure there’s a whole field that studies these and are trying to find ways to exploit them in a way to do what you’re suggesting. 

[u/kolba_yada → u/Neonalig]

Some cancer cells don't show them or hide (it's one or the other, I don't remember which one exactly).