Natural Killer Cells: a Fascinating Evolutionary Arms Race

[@SteveMould]

I've got another video coming about how Killer T Cells are made. It's crazy. The sponsor is Skillshare - the first 500 people to use this link will get 2 free months of Premium Membership no strings: skl.sh/stevemould9

[@iloveengineering2242]

I think it's helper t cell idk correct me if I'm wrong

[@TheHookUp]

@@iloveengineering2242 helper T's and Cytotoxic (killer) T's are different cell types and have very different functions. Helper T cells are there to make sure your immune system doesn't attack your own cells.

[@DarkSlimeSera]

I just want to say I learned this from the Cells at Work anime first.

[@iloveengineering2242]

Ok

[@andrezzz_]

As a medical biotechnology student, I absolutely love these kind of topics! I really like your videos and your ability to communicate to the public, without going into many complicate details. Also, earlier this year, a group of researchers in Cardiff University discovered a particular subpopulation of killer T cells that could have the potential to recognise many types of cancer via a mechanism similar to MHC1. That would be a huuuge step forward for scientific research. Looking forward to the next video on T cells!

[@x--.]

Who's a good Killer-T? Who's a good Killer-T cell? YOU, you a good Killer-T cell. So good.

[@TheHookUp]

As a high school biology teacher I always watch your videos with a shred of terror that I have been teaching things the wrong way for 15 years. Marking myself safe on this one, well done.

[@TheHookUp]

Also a few other extensions I think are pretty cool: 1) NK cells play a large role in the prevention of cancer presumably due to the fact that cancerous cells produce very few non-growth based protein products. 2) Stress seems to lower overall NK counts in the body, again, presumably to allow the body to recover from physical injuries.

[@epochdoc2259]

X factor drug being called by out of control cells help get good circularity to the cell for proper drug perfusion.

[@letsgocamping88]

Do you also cover yourself in fabric in a ball on the floor while waving around pipe cleaners?

[@elooflskhu5358]

So our bodies are nothing but giant fascist police states?

[@samwalker4438]

The animations are excellent but I kinda love the lofi live action representations, like the vision molecule video 😂

[@heaslyben]

I feel the same. I am feeling the "both and" energy.

[@hueyiroquois3839]

He should have had the dog demonstrate the release of cytotoxins,

[@zonzaykay]

Shouldn't have read lofi as loli fkkkk

[@stevethea5250]

@@hueyiroquois3839 timestamp

[@NonExistentAlex]

My therapist: Steve Mould in a bag isn't real, he can't hurt you.

[@iitool]

Dude, there is a dog in your circulatory system. I dont think you should be so worried about a virus right now

[@DoctorX17]

Cell Steve is the best thing to happen to this channel

[@mjames7674]

When is Killer T Cell dropping his next album?

[@germenfer]

This made my day, thanks!😂

[@AaronRotenberg]

Someone please clip 3:18-3:27 and upload it with no context.

[@CaveyMoth]

Don't forget 5:16 - 5:21 !

[@MrOrzech1]

What about 6:01-6:05?

[@ChaseMakes]

So I clipped all of them and made a playlist for it. Here's the link: kzbin.info/aero/PLjZhB1wzjtSChhksucxU4gv0q5NzfNyBv I hope you have a good day.

[@marquez2447]

@@ChaseMakes Beautiful.

[@anothrto1045]

No context Mould is the oddest

[@diogonunes1865]

"I am not going mad" "This process is happening all the time inside a healthy cell"

[@imveryangryitsnotbutter]

*a padded cell

[@QuietSk8er46]

Can you do a similar video on allergic reactions? I've had food allergies for years and I've had several scary close calls (or at least that's how I perceived them) only to be looked at funny for showing up at urgent care. The information you've presented like this at such a simple-to-understand but also really in-depth level would (A) raise awareness for people with allergies and their experiences and (B) help people with allergies FIFO (find out before they freak out) which can save money (not having to visit a hospital for small reactions) or save energy spent worrying. Thanks for your amazing videos!

[@raykent3211]

I second that request! A cousin of mine has a dangerous allergy to peanuts, hospitalised three times. Others speak of "nut allergies". But a peanut is not a nut, it's a pea, a legume like a pea or lentil. She's fine with true nuts and all legumes except the so called peanut. Eh? Good territory for Steve.

[@BrigadierPickles]

I love how you cut it so the video at 00:00 is instantly you talking about the video. You cannot get any further away from the Wadsworth Constant.

[@user255]

It's quite useless constant anyway. I don't think I have subscribed to any channel where it applies.

[@Xenro66]

Thank you for sharing this, I had no idea this even existed. I looked it up, tried it out in some messages I've sent to friends (and ones they've sent me)... And this "constant" is eerily close to working flawlessly. I can take basically any transcript, cut off the first 30% or so and the meaning remains in tact. E.G: your initial post, trimmed as close to 30% without cutting into a word or being grammatically wrong: "00:00 is instantly you talking about the video. You cannot get any further away from the Wadsworth Constant." That was a 25% cut. Fascinating!

[@burt591]

@@Xenro66 kzbin.info/www/bejne/imekYalprb6fbc0

[@ncot_tech]

It also applies to the end of videos too.

[@user255]

@@Xenro66 It "works" only because you know the cutted content. Let someone else cut beginning of something you have not read and it definitely does not work.

[@paulsmyers203]

Dog, "Oh no. The human that provides food has gone mad. I'm totally screwed."

[@Talaxianer]

8:45 How does the natural killer cell detect that the number of MHC molecules is small?

[@Kermal111]

NK cells do not only bind to MHC, but also a few different things that are expressed on both normal and abnormal cells. Some of them trigger NK activation, some inhibit it. MHC is one of the things that inhibit the response. So if it happens to bind to a cell with low MHC expression, the balance will swing towards activation and the cell will be killed.

[@ilikaplayhopscotch]

Bartosz Makowski thanks! Not sure I’ll ever need to know that, but I do!

[@buttonasas]

@@Kermal111 What does "low MHC expression" mean and, more importantly, how is it detected?

[@electronresonator8882]

@@Kermal111 I see, only cells with normal number MCH expression are preserved

[@nickpatella1525]

That Scar “express” means “to show on the surface” more or less. So if a living thing “expresses a trait”, it has that trait in its DNA and exhibits it. Expression of a trait can be disabled or inhibited when something blocks the creation of the proteins or whatever is necessary to show that trait.

[@britishidiots3842]

The immune system and the brain - the two most complicated systems of the human body, three years into a degree in biomedical sciences and I’m still completely baffled by the both of them

[@lecuyermarcandre]

I've spent 15 years studying both and I'm still there with you. That feeling won't stopped. 😋

[@Cosmolovescheese]

Man have you looked into the biochemistry involved in the liver??? The body is just mad complicated in general 😅

[@NicksAreOverrated]

Small correction for 1:32 - Ribosomes do not read DNA but mRNA which is based on your DNA but slightly different

[@jamesmnguyen]

While correct, it doesn't apply to the topic at hand.

[@amineaboutalib]

he obv knows, but it indirectly reads dna, he's not wrong

[@brunojambeiro6776]

That’s right. He mentions it on a different video p( I think it was the one about magnets and virus).

[@qnicks23434]

There's an anime on Netflix about it. "Cells at work".

[@defaultmesh]

6:22 i don't know why i expected you to say "it can no longer respawn"

[@iwanabana]

just a small tiny thing that bugged me: the "green tick"/"red cross" seems like a poor choice for the mechanism, as the red cross may also suggest that the proteins don't fit. Better would be "don't care" vs "ooooh, a match!" followed by a big red exclaimation mark.

[@Christopherfife]

What about the poor old dendritic cell? That CD8+ T cell needs priming. Loved the video, as always. A great job at simply communicating complex information.

[@CircuitrinosOfficial]

@6:01 You should have used a dog treat for this one.

[@pyromen321]

I’m always impressed by both the quality of your videos and your proud lunacy!

[@JakubH]

wow :O I am always amazed how such a complicated mechanisms evolved just by natural selection

[@TheDeGhoul]

Now Im sitting here utterly amazed like the way I use to feel in school Biology. I had always been fascinated to learn about how mother nature does things. It has been a long time since someone re-ignited that same feeling in me. I enjoy watching informative videos such as this on many different topics, but for some reason, this video made me feel like a child again. I was so disappointed when the video ended. I wanted the explanation to go into how the sickness then araises in the body, like the HIV or Corona example. Thanks. I'm looking forward to the next one Steve.

[@jacobprentice2649]

Long comment=bigger brain so good for u

[@Sauspreme]

I'm glad you put in animations. But at the same time, I'm glad you filmed the live action adaptations as well.

[@craquerbarrel]

Steve Mould, I listen to your videos while working and it is nice experience. Thank you for your work.

[@RFC-3514]

8:38 - "Papers please. Your papers look fine... but you do not have _enough_ papers. Please execute yourself, for the glory of Apoptotzka."

[@ChaseMakes]

So I clipped all of the moments where he used himself inside a blob and made a playlist for it. (3:18) Here's the link: kzbin.info/aero/PLjZhB1wzjtSChhksucxU4gv0q5NzfNyBv I hope you have a good day.

[@tobiasthrien1]

6:06 Isn't that just amazing? In order to protect itself the body developed a self destruction mechanism. You just need to need to release some cytotoxins and the cell dies. At a first glance that sounds like a pretty big vulnerability. Harmful organism could use the same mechanism! But they don't because it is not in their interest. They need the cell. So insteed this becomes extra save. Despite exposing itself so much (i.e. making it easy to kill the cell) it doesn't have to fear being exploited because no one benefits from just killing everyting. That was a lot of anthropomorphizing, but i was just to excited to keep this for myself.

[@raykent3211]

It's fascinating. You can't repair a car engine without replacing parts, and an animal's body needs to keep replacing cells. The outer layer of our skin is exposed to UV, may become cancerous, so we routinely kill skin cells and shed them. That may account for most of the dust in your house.

[@youtubersingingmoments4402]

The altruism is staggering. If I could, I'd give a military-style funeral to every one of my cells who made such a sacrifice for the greater good. They do it without asking questions, which makes me wonder how much more efficient humans would be if we didn't have emotions or consciousness... imagine if everybody was in this together for the advancement and protection of our "body" (the Earth and our species).

[@ygrabo]

Molecular biologist here; everything you said was correct :) Simplified, of course, but correct. That's good to see!

[@VyvienneEaux]

I just read all about these in a textbook for four hours this morning! I think you must be tracking my studying habits just to release videos at the best time, because this sort of thing happens regularly.

[@groupcaptainbonzo]

Brilliant. Informative, entertaining. At just the right level. Fabulous stuff

[@luxbalthazar7646]

This was phenomenal. I often find this subject matter ineffable and you ingeniously illustrated it. Bravo!

[@rixzvice8875]

Studying Immunology & Disease with college right now. Probably the first Steve Mould video I was able to keep up with!

[@trawelgrad5471]

Dat live-action! WoW! Made my day :)

[@Cerevisi]

If I wasn't unemployed, and struggling for $, I would be a patreon. Best I can do is share this content with friends... Great stuff Mr. Mould! Am a fan!

[@foofighter8173]

This morning I was reading the exact same topic so extremely coincidental but really happy there was a further explanation of other cells, thanks a lot.

[@lockhandel]

Excellent video. Keep up the good work Steve!

[@Lukionest]

Love your videos. An idea for you to investigate: I like to drop a couple of ice cubes into my Keurig-brewed coffee because it is initially too hot to drink. Since the ice cubes from my fridge are all the same size, I tend to think of them as all having equal amounts of cooling power or "coolth" (a term I've made up which is the opposite of warmth.) Usually I drop the cubes in right after brewing is done, but I've also dropped them in near the beginning of brewing. What I've wondered is if the Keurig introduces the same amount of warmth to my mug each time and the ice cubes deliver the same amount of coolth each time, then how does introducing the ice earlier in the brewing cycle affect the final temperature of the coffee, say two minutes after brewing is done, assuming the ice has completely melted by that time in both cases? There are lots of variables here. Does the longer cooling time when introducing the ice early result in colder coffee or does the greater temperature difference between the coffee and the room allow for more heat transfer, and thus colder coffee when introducing the ice later?

[@ChaosPootato]

I like "coolth" hahaha I have pretty much zero deep knowledge of thermodynamics but I'd say if there is a difference it's gonna be really small because the area of exhange between the hot coffee and the colder air is quite small compared to the volume of liquid in the mug. For my surface level understanding, putting the ice right after the brewing would result in a slightly warmer coffee in the end because of the temperature difference being lowered faster as you stated

[@VyvienneEaux]

Sorry to obtrude-- does the Keurig have a hotplate like a regular coffee machine? That might be a good variable to mention here.

[@retnuh360]

Does the coffee spread all over the ice when put during the brewing? Cause I guess that a liquid flowing on/spread over a surface have more efficient thermal exchange with the air rather than when flowing in a standard tubular shape directly into the mug. Only trying to guess here, must not be that, curious of the answer BTW! Note that it could be easily tested for by putting the ice after brewing but having a similar shape made out of something not as cold as an ice and then compare with the "ice after" case. (thus eliminating the "coldth factor and only keeping the pouring shape factor")

[@heaslyben]

This question reminds me of a Matt Parker video from a while back. I think it's relevant -- do you find it to be applicable? kzbin.info/www/bejne/eXTYkoqnnbupf8U

[@heaslyben]

I totally love "coolth" 😁

[@iCandlelightCrusade]

Have you heard of Cells at Work / Hataraku Saibou? It's an anime with anthromorphic cells such as Killer T cells, red blood cells, macrophage etc. Seems similar to this topic!

[@Agent-47-eh]

You look like one of my Chemistry teachers back in school who accidentally started a fire but was loved by all. Great video

[@emilsvahn5400]

The video quality is fantastic!

[@MaryAnnNytowl]

"I am _not_ going mad," he says to an empty room. This feeling I know. This feeling I live.

[@YotamPeleg]

Steve love biology more than other topics I see. As do I. Love both his topics and his explanations.

[@kale991]

Oh god it's the vsauce effect. Steve is slowly starting to lose his mind too

[@grantpeterson2524]

It’s crazy how similar viruses in computers and in microbiology behave. Killer T cells are like antivirus programs, going through your system and comparing literal “bits” of data to a database that is known to be dangerous. As a mechanism to prevent this, the viruses oftentimes try to selectively disable the ability of the antivirus to scan where it resides

[@midotah]

you did a nice job, much simplified , but for more detail here the best documentary to explain it well

[@dylanbarclay7818]

Honestly this seems like its beyond me, but Steve's explanations make things seem so normal and logical.

[@GFmanaic]

« So.... how do you make a living? » Steve: 3:19

[@BryanWLepore]

The remarkable protein complex that translocates the proteasome peptide products is - IIANM - the Peptide Loading Complex : en.m.wikipedia.org/wiki/Peptide_loading_complex ... of which the Transporter Associated with Antigen Processing is just one part : en.m.wikipedia.org/wiki/Transporter_associated_with_antigen_processing (Edited : added PLC as the main point of this)

[@Cosmolovescheese]

oh god no don't remind me of studying MHC loading 😅 horrifying flashbacks

[@nseaspatetico]

You definitely deserve more views than these. Commenting for the algorithm!

[@jfraser3]

3:30 Im not going mad ..... i think ya all ready halfway there ;) keep up the good videos.

[@kyrothegreatest2749]

Fantastic video as always

[@shlimeball475]

The killer T cells are like the bodyguards for the bodyguards if that makes sense

[@Gr0nal]

It baffles me that the natural killer cell can 'count' the MHC molecules... how does that work?

[@lecuyermarcandre]

It doesn't really count anything. Having normal MHC-I molecule on the surface gives the message to NK cells that everything is normal. It acts as a negative signal, preventing the activation of NK cells. If there isn't enough MHC-I there's less chance that the NK cell will come in contact with one. Also, if the cell is infected by a virus or it is a cancer cell it will also have on the surface other molecules that are giving the NK cell positive signal (meaning a signal to activate the NK cell). Therefore, the absence of negative signal and the presence of positive signal activates the NK cell which kill the cell infected with a virus or the cancer cell. It's a bit more complicated then that, but that's the main idea.

[@questionminecrafter]

@@lecuyermarcandre thanks for the explanation, it really cleared my doubt!

[@chrisg3030]

@@lecuyermarcandre You say "Also, if the cell is infected by a virus or it is a cancer cell it will also have on the surface other molecules that are giving the NK cell positive signal (meaning a signal to activate the NK cell)" But doesn't Steve say HIV initiates endocytosis on such molecules (pulls them back in), at least enough to avoid detection by NK cells?

[@lecuyermarcandre]

@@chrisg3030 some cancer and some virus have evolve ways of hiding from the immune cells. That's one of the way, but not all of them do. They can also force the cell to produce molecules that give a "don't kill me signal" to immune cells. Some molecules express by cancer cells can even promote death of immune cells or render them ineffective.

[@chrisg3030]

@@lecuyermarcandre Are there situations where "don't kill me signals" are disobeyed by the NK cells, for example if there's also an MHC1 molecule on the surface presenting a viral fragment? Anyway, one thing we can be sure of seems to be that there's no "final step" in this deception and counter-deception story, despite what Steve says at 8:28.

[@LaGuerre19]

In this video: The Hopes and Dreams of Viruses. Next up: The thoughts and prayers of paramecia, The will to power of tardigrades. All joking aside, this was a brilliant explanation -- blue body suit and all.

[@COM70]

Brilliant and humerous.

[@tanman999]

Do one on Prions.

[@trelligan42]

That hair, those eyes - yet he *_sounds_* calm ... and sane ...

[@ardeneques]

Great video thanks Steve, looking forward to the next one and more like these.

[@cedalege]

Love your videos Mr. Mould!!

[@Yahgiggle]

fantastic video very interesting - love this sort of teaching / learning

[@mayank5636]

This is SO AWESOME!!

[@markfrellips5633]

These are collegiate level topics but if you presented this to children with the life-action demonstrations, kindergarteners would be yelling, "Tag, Apoptosis" as they play in the courtyards

[@l1keagrrrl]

Stumbled upon your video about entropy and now im invested

[@Luxcium]

😳 WOW !!! You kept me interested in the Skill Share part (after clicking away a million times in other youtube videos I am now fully trained to click away at the exact moment *JUST BEFORE* the host is about to wrap up with sponsors... lets pretend this conditioning is now “part of my ADN“ [see I am using inverted quotes ' “ ' instead of normal ones ' ” ']) If one day for a reason or an other I decide to subscribe I will make sure to go trough your affiliate link !!! (Probably no one will ever see how much effort I put into my comment unless people are liking up my comment with the blue thumb up)!

[@GordonWrigley]

Nice explanation, it'd be cool to hear about the rest of the system. Where do the Killer T cells come from, how do they know what to look for etc.

[@Cosmolovescheese]

Oof blimey those are some big questions there with answers that you can study for years. Sounds like you want to look up about haematopoiesis, and VDJ recombination

[@tim40gabby25]

Beautifully explained.

[@AlintaMcMurdo]

So this is why I’m so screwed without nk cells. Can you please do more immune videos. NK cells aren’t the only thing I’m deficient in so I’m sure you will cover others I don’t have if you do enough of them lol.

[@NeilGirdhar]

Great video. You could tie this in with the revolutionary new cancer treatments: chimeric antigen receptor therapies whereby the immune system is trained to attack cancerous cells.

[@nonnnth]

Proteasome sounds like a word to describe something involved with tea

[@CrazyBunnyGuy]

And this, among many other similar tales, is why I decided to study biology (especially immunobiology) at the university. :)

[@frankowalker4662]

Well explained, thank you.

[@mehmetdemir-lf2vm]

excellent video. animations are awesome too :-)

[@112048112048]

Everyone else: _"Go to es kay el dot es aitch or use my link in the description..."_ Steve: _"Go to skull dot shhh..."_

[@sidharthcs2110]

New graphics looks amazing

[@vertexrikers]

Reeeaally expected you to hold out a sausage for the dog at 6:02 ;D

[@jaquo25]

The scale of it is mind boggling. To think that there are individualized T- cells, not for each virus, but a different one for each of the myriad snippets of proteins that might be presented by each virus. There's probably some overlap, though, since viruses do share a lot of code between each other so one T- cell might actually detect more than one virus that share the protein that it's coded for. I wonder if that's how some immune related diseases are caused when T-cells get coded for virus proteins that also show up in human code?

[@MCUxDaredevil]

I was just curious and thought if there really is a disease or a syndrome that makes the Killer T cells malfunction. Do you know about anything like that? Something that makes the Killer T cells think that normal human proteins are harmful or have originated from a virus?

[@Cosmolovescheese]

Absolutely, there are many! Killer t cells undergo lots of strict controls (called tolerance) to make sure they don't attack your own body. Some examples are multiple sclerosis, rheumatoid arthritis, and diabetes!

[@chichcnc]

Khaaa haaa ha! That was Brilliant! LOVE your humour! Another great video Steve.

[@danielroder830]

You say that viruses have "found ways", but viruses are not really living things. What i would like to know more about is how exactly did viruses come to exist and how and why do they evolve.

[@lecuyermarcandre]

They evolved for the same reason we do, because having some traits facilitated their reproduction. As for where they are coming from, I don't think there is a consensus yet, but one hypothesis is that a transposon (jumping DNA/gene) found it's way in a vacuole formed by a cell and "infected" another cell.

[@invictusdomini8624]

"Let me tell you what I've been learning recently with SkillShare," Noped right to the pause button, you're not going to fool me! O_O

[@maxximumb]

3:19 I feel dirty after watching that.

[@arnold-pdev]

Before the immune system developed, what could possibly slow down the spread of viruses? Did the emergence of viruses trigger an extinction event?

[@lecuyermarcandre]

An "immune response" as been around since the first uni cellular organisms. So the complexity of the immune system has evolved with every species.

[@generalpartridge7653]

Awesome video, very interesting

[@HasanProd]

Great Video, Kudos

[@Convolutedtubules]

I love the humour in this one. Take it easy Steve.

[@Aditya-yg1ce]

The doggie finds a red protein made of beef jerky and then he secretes fluid to the blue glob.. and the blue glob blows up 😂😂.. Cheers Steve..👍🏼

[@timsarai]

Another great video 👍

[@bazoo513]

Very good. A natural next video would be about autoimmune diseases.

[@jimmybutler3728]

Good explanation keep up the good investigations...

[@RafaIII]

great video as usual. I laughed out loud with the real life representation :)

[@Wolforce]

Hah "I'm not going mad! ". Keep trying to convince yourself mate. XD Awesome video, as always!

[@HuyV]

How such complex chemistry evolved (read trial and error with random mutations) is kinda mind boggling.

[@nebularwinter]

Cool! Where did you learn this stuff about the immune system?

[@diwakar8815]

the best "Cell" Cosplay ever at 3:18 lmao................

[@oddessy5633]

rest of the immune system: "we look for the presence of the unexpected." Natural Killer cell: " I look for the absence of the expected."

[@radubasturescu5798]

Natural killer cells: There is an impostor AMOGUS

[@julienbeavis448]

Ooo, loving the use of skulduggery.

[@DeclanMBrennan]

One question: How does the Natural Killer Cell know there are too few mh2 molecules on the surface? Is it doing something analogous to counting ? Amazingly sophisticated.

[@Cosmolovescheese]

So natural killer (NK) cells don't just recognise MHC, they recognise lots of surface molecules on cells. Some are stimulatory for the NK cells, some (like MHC) are inhibitory. If the stimulatory outweighs the inhibitory, the NK cell is activated and induces apoptosis. It's not a discrete counting system, more a threshold of rates of reaction within the NK cell