I wanted to start with a little history. These are some beautiful illustrations from the

我想先從一點歷史開始。這些美麗的插圖都是來自一本長達千頁的書

Florentine Codex which is thousands of pages long. It was created over about 45 years by

書名是 - Florentine Codex。這本書花了超過45年的時間製作

this guy, this friar. And basically what we did was he studied Aztec culture and how it

作者是這位修士。基本上他研究阿茲特克文化以及它如何

changed over his lifetime. So we've converted a lot of this to English and you can find

在他的一生中改變。然後我們已經把很多他的內容翻譯成英文

some if it on Wikipedia. It's just fascinating. So you could see these rituals and these chieftains.

你可以在維基百科上找到相關的資訊。它們非常吸引人。你看這些傳統儀式和頭目（首領）。

And he would describe all of it. But a sad part of that is that he describes how small

他描繪了這一切。但可悲的是他描述了天花

pox came and devastated the Aztec. And it's one of the reasons why the Spanish were able

如何降臨，然後摧毀了阿茲特克人。這就是其中一個西班牙人能夠

to conquer them. And so they didn't have a immunity to it. And that's what this is about.

征服阿茲特客人的原因。總而言之，這一切都是因為他們對天花沒有免疫力。

So basically what happens with any kind of a infection, a viral infection like this,

基本上任何類型的感染，或是病毒感染，

is you have a virus. And that virus is essentially going to gain entry inside your cells. It's

都是病毒造成的。這些病毒必需進入到你的細胞內。

going to use the machinery of your cell to make copies of itself. And more copies of

它利用你的細胞，複製更多的自己，做出更多的病毒。

itself. And more copies of itself. And eventually it's going to destroy the cell and it's going

最終，他會摧毀那細胞，然後散佈出去，感染其他的細胞。

to spread off to infect other cells. And so that seems awful. In other words when you

這一切似乎很可怕。換句話說，當你感冒時，

get a cold what's happening is that your cells are making viruses which are spreading to

你的細胞正在製造病毒，然侯傳染到更多的細胞。

more cells. And if it weren't for our immune system we would be devastated by all the viruses

而如果不是因為我們的免疫系統，我們將遭受到我們身旁所有病毒的摧折。

that are around us. And so we have to have protection. And so I like the analogy of a

因此，我們必須要有保護。我喜歡的把這比喻為

castle. A castle needs protection as well. And so if you're building a castle, you have

城堡。城堡也需要保護。所以如果你正在蓋一個城堡，

to think about a few ways to defend yourself. First of all you have to defend yourself from

你一定要想想如何保護自己。首先，你要保護自己

the outside. So it's good to have a moat. It's also good to have a really large wall.

受到外部的干擾，所以有條護城河還不錯。蓋座圍牆也是個好選擇。

So it's hard for people to get over it. And this castle's great because it's got water

這樣外人就不容易進去。這個城堡很棒，因為它周圍有水

on all sides of it. You also have to have soldiers. So if anybody were to ever get close

你還必須有士兵。這樣如果任何人接近大門

to the gate you could shoot them with arrows or pour hot tar on them. But if they were

你可以用箭射他們或潑他們焦油。但是如果他們

to breach the wall you have to be able to fight them there as well. But probably when

能闖到圍牆，你還是要和他們奮戰。

you're defending a castle a more important thing is you have to have intelligence. You

但當你在保護城堡時，更重要的事莫非於有智力了。

have to have spies that are sent out to surrounding areas to do reconnoissance and figure out

你必須派間諜去附近偵察或蒐集情報

what's going on. To recognize invaders when then come. And so I'm going to quit talking

瞭解入侵者何時會來。現在我要結束城堡這話題。

about castles and we're going to talk about the immune system. But the same thing works

我們要來談免疫系統。但同樣的事情也在我們身體中發生著。

inside us. And so the idea of a castle wall. Let's start with that. And so what protects

從城牆開始。到底是甚麼在保護我們不受到感染

us from infection, our castle wall is going to be our skin. And so what our skin provides

城堡的城牆就像是我們的皮膚。我們的皮膚提供我們一層屏障

us with is it provides us with a barrier. So there's going to be a barrier of cell,

所以這屏障是一堆的細胞

dead cells, on the top. And keratin on the top. It's also going to have a really low

在頂部（上層）的是死掉的細胞。然後角蛋白在它的上面。 所以它的pH直非常低。

pH which makes it hard for any kind of bacteria to live there. And we're also going to have

pH值正是造成細菌很難生存的原因

chemicals on the surface of our skin that are going to disrupt certain viruses. And

在我們的皮膚表面還有些化學物質會破壞某些病毒

also we're going to have bacteria that crowd out our skin. And so it makes it hard for

同時我們還有一層細菌覆蓋在我們的皮膚上

other bacteria to gain entry. We have what are called normal flora that just live on

所以這讓其他的細菌難進入到我們體內。我們有個叫"皮膚正常微生物叢"的東西在我們皮膚上

our skin. And so all of this is going to provide protection against infection. But occasionally

所以這些東西全部都在保護我們受到感染。

you know that that get's breached. Occasionally you cut yourself or a pin prick or something

但偶爾，他們還是會被侵入。有時你會割傷或刺傷自己。

like that gains entry. And so that would be just like the soldiers making it over the

劃出傷口，讓細菌有機會進入到你身體裡。這就像是士兵們翻牆進入城堡一樣。

wall. And so what do we have? Well we have a call to arms. We have inflammation. So basically

結果勒？我們要下令軍隊開戰了。我們發炎了。

we have chemicals that are released that cause our body to respond to that. Now you constantly

導致我們的身體釋放化學物質做為回應。

are being infected, especially if you are a teenager because you get acne. So what is

現在的你不段的受到感染。尤其是青年們，因為你們有青春豆

acne? Acne is essentially an infection in the pores of your skin. So it's bacteria that

什麼事青春痘？它基本上就是皮膚上的孔受到感染造成的。

are living and feeding inside our body. And so how do we fight that? Well we'll plug it

所以它們就是住在我們身體裡從我們這裡得到能量的細菌。 那我們怎麼抵抗它們？

up for one thing, but we have swelling. So we're going to increase the heat. But basically

它們會腫脹。所以我們要增加他的溫度。但基本上

we're going to send soldiers in there. And those soldiers are the macrophages. Those

我們將在派兵去那。這些士兵是"巨噬細胞"。

are going to be the eaters or the big eaters. And what they're going to do is they're going

它們就像體內的清道夫。而他們要做的事就是

to find anything that's not part of our body and they're going to eat it. So any invader

把發現不是我們身體的一部分東西都"吃"掉。

is called antigen. And so basically what a macrophage will do is it will notice that

任何的入侵物被稱為"抗原"。巨噬細胞會找到不是我們身體的一部分

this is not part of our body. It will grab on to it. It will take it into the macrophage.

它會抓住它然後把他帶入巨噬細胞內。

It'll secrete lysosomes and enzymes into it which break it up. It will lots of times present

它會分泌溶酶體和酶到它裡面，破壞它。

that on its surface, but eventually gets rid of it. And so this is an actual picture of

很多時候它都會在表面上，他是最終都還是會把他踢出去。

a macrophage. And you can see it's grabbing I don't know if it's viruses or bacteria on

這照片就是一個巨噬細胞。你可以看到它抓一個病毒或細菌我也不確定

either side. And so that's great. But the one thing about it is it attacks anything

這棒極了！但重點是他會攻擊任何不是我們身體一部分的東西

that's not us. In other words if you get a heart implant from someone else, or you get

換句話說，如果你有心臟植入，或者你有心臟移植手術

a heart transplant, those macrophages are going to attack it as well. It's going to

這些巨噬細胞也會攻擊它。然後把他們摧毀掉

kill that. And so we also have what's called a specific immune response. Specific immune

因此我們也有"后天免疫系统"

response is more like the spies. And so basically here's an antigen again. An antigen is going

后天免疫系统就像是間諜。這是個抗原。

to have specific proteins on its surface. But to fight that we use what are called antibodies.

這抗原的表面上的特定的蛋白質。要對抗它們，我們必需要用抗體

And so the name antigen means an antibody generator. In other words it generates the

抗原的名字就是指抗體產生器（以英文來說Antigen = 'Anti'body 'gen'erator）。換句話說，它會製造

formation of antibodies. So what are antibodies? Antibodies are going to be proteins produced

抗體的形狀。那麼什麼是抗體？抗體就是我們身體製造的蛋白質

by our body. And basically they all look the same. They're this Y kind of a shape. So they're

基本上他們看起來都一樣。他們長得像這樣 - Y形狀的。

a Y shape like this. We produce almost an infinite number and an infinite variety of

我們出和各式各樣不同種類的抗體和數不清的抗體

them. But at the top of the Y you're going to have different shapes. In other words,

但在頂部的Y要具有不同的形狀

you're going to have a shape that looks like this. But you're also going to have an equal

換句話說，你可能會友形狀看起來像這樣。但你也可能會有像這樣的形狀

shape that might look like this. And you're going to have an equal shape that might look

或看起來像這樣。或有一個相同的形狀看起來可能像這樣

like this. And so we're going to have all of these different shapes at the top. But

所以我們將有所有這些不同形狀的頂部。

we're only going to produce the shape for the one thing that we're infected by. So basically

但我們只打算製造出可以對抗侵入我們身體的抗原的特定的行狀

the antibody will dock to the antigen. And when it does that basically it marks the antigens

抗體會綁住抗原。當它綁住抗原時，它對抗原作上了記號

so macrophages can find it. And it also makes it harder for them to do their job. Imagine

所以巨噬細胞能找到它。這也使得他們更難完成他們的工作。想像一下

if I had another antibody here. And another antibody here. And another antibody here.

如果我在這裡有另一個抗體。另一個抗體在這裡。另一個抗體在這裡。

It's hard for them to do their job. And so when you gain immunity, specific immunity

這是很難讓他們完成工作。因此當你獲得免疫 - 后天免疫系統

or specific immune response what that means is you have the ability to produce these antibodies.

后天免疫系統讓你有能力製造這些抗體。 這就是為什麼當你感冒時，你不會再得到相同的感冒。

And that's why when you have a cold you're not going to get that same cold again. And

所以我們怎樣才能做到這一點呢？如和辦到的呢？ 我們需要淋巴細胞（淋巴球）。

so basically how do we do this? Or how does this work? Well we need what are called lymphocytes.

淋巴細胞是白血球的一種。基本上淋巴細胞分為兩種。

Lymphocytes are a type of white blood cells. And so basically there are two types of lymphocytes.

可分為T细胞和B细胞

There are B lymphocytes and then there are T lymphocytes which will get to in just a

好吧。B淋巴細胞是在骨髓中製造的。他們負責

second. Okay. So B lymphocytes are made in the bone marrow. And they're responsible for

體液免疫反應。我將在播客中再提到這單字很多次。

a humoral response. Now this term I'm going to show you a couple more times in this podcast.

體液是指在液體中。像是在血液中。

Humoral means in the fluid or in the humers of your body. So that means in the blood.

在淋巴裡，淋巴管，在組織液（間質液）。

In the lymph material. In the lymph vessels. In the interstitial fluid. And so humoral

體液反應，就是任何時候，有細菌在我們身體的液體裡。

response, what I want you to think about is going to be anytime there are viruses free

B淋巴細胞的工作就是製造抗體。

in the fluids of our body. And what the B lymphocytes do is they produce antibodies.

那麼它們是如何做到呢？基本上你有一個NaiveB細胞(=還未接觸抗原的Ｂ細胞) 他將去感應他抗原的形狀

So how does that work? Basically you have a naive B cell. It's going to sense the shape

我等一下會告訴你他怎麼做到的。

of the antigen. I'll tell you how that works in just a second. But basically what it's

但它主要就是製造抗體。因此B淋巴細胞的工作就是是要造特定的抗體給特定的抗原

going to do is it's going to produce antibodies. And so what B lymphocytes do is they produce

換句話說，如果我們被細菌感染

all of these antibodies that are specific for the antigen. So in other words if we're

我們稱這個病毒A1，我們將製造特抗體給特定的抗原

infected by this virus, we'll call this virus A1, then we're going to produce antibodies

我們也將製作記憶B細胞，使我們對特定的細菌有一輩子的免疫力

for that specific antigen. We're also going to produce memory B cells so that we have

所以那些是B淋巴細胞 你也許想說

that immunity for the rest of our life. So those are the B lymphocytes. And so you might

如果他們攻擊我們身體內的病毒，那麼T淋巴細胞做什麼呢？

think, if they attack the viruses out inside our body then what do the T lymphocytes do?

T淋巴細胞是負責細胞介導反應。這是什麼意思呢？

Well the T lymphocytes are responsible for cell mediated response. What does that mean?

他們將瞄準並殺死我們身體內已經被感染的細胞。

They're going to target and kill the cells inside our body that are already infected.

好吧。那麼什麼是T淋巴細胞嗎？他們在哪裡製造？答案是胸腺

Okay. So what are the T lymphocytes? Where are they made? They're made in the thymus

胸腺在我們的心臟上面。基本上他們製造

gland which kind of sits on the top of our heart. Basically what they do is they create

自然殺傷Ｔ細胞。因此殺傷T細胞是活化的T細胞。

what are called kill T cells or killer T lymphocytes. And so a killer T cell is an activated T cell.

基本上它會在我們的身體內找到所以被細菌感染的細胞

Basically what it will do is it'll find any of the cells inside our body that are infected

它會綁住它們然後殺死那些細胞。

with a virus. It'll dock next to them and it will kill our own cells. And so it's going

他不僅會殺死我們的身體內被病毒感染的細胞。甚至會殺死癌細胞

to kill any of the cells inside our body that are infected by the virus. Or even cancerous

所以它是在胸腺中製造的，然後使我們的細胞死亡

cells, it's going to kill them. So it's made in the thymus and it produces cell death inside

所以T淋巴細胞負責細胞介導，意思是殺死我們體內被感染的細胞

us. And so the T lymphocytes are responsible for this cell mediated, I mean killing cells

我來總結一下下，這上面是體液免疫反應

inside, our cells that are infected. B lymphocytes are going to be in the humers of our body.

那麼是什麼細胞負責的呢？答案是B細胞。

And so if I were to summarize this a little bit, this would be the humoral response up

這下面是細胞介導。負責的是T細胞。

here. So what type of cells are responsible for that? Those is going to be the B cells.

讓我們先來看看左邊這裡發生了什麼事？

And here's the cell mediated down here. Those are going to be the killer T cells. And so

有個被巨噬細胞吃掉的抗原。巨噬細胞將會把抗原用碎。

before we get to that let's look over here on the left side. So basically what's happening?

然後把碎片從表面釋出。因此我們使用一種化學物質叫MHCII(major histocompatibility complex II)。

We have an antigen that is eaten by a macrophage. That macrophage is going to chop up that antigen.

這是第二型主要組織相容性複合體。它要他的表面上呈現抗原的形狀

It's going to present pieces of it on its surface. And so we use a chemical called MHC2.

然後我們將用到這個超級重要的細胞，叫做輔助型T細胞

It's major histocompatibility complex 2. It's going to present the shape of that antigen

輔助型T細胞將綁住然後偵測抗原的形狀

on it's surface and now we get this cell right here which is super important. It's call the

它使用另一種蛋白叫做CD4 (cluster of differentiation 4 表面抗原分化簇4受体)

T helper cell. What the T helper cell is going to do is it's going to dock and it's going

來檢測抗原的形狀。輔助型T細胞則是負責啟動

to physically sense the shape of that antigen. It uses another protein called CD4. And it's

體液和細胞介導的免疫反應。 讓我們來看看什麼輔助型T細胞要做什麼

going to sense the shape of that antigen. The helper T cell is responsible for initiating

輔助型T細胞是要把那麼形狀告訴B細胞

both the humoral and the cell mediated immune response. So let's see what helper T cell

所以它可以產生更多的抗體。它要激活巨噬細胞。因此它可以殺死更多的細胞

is going to do. Helper T cell is going to tell that shape to the B cells. And so it

因此它是負責體液免疫的反應。

can produce more antibodies. It's going to activate macrophages. So it can kill more

輔助型T細胞也將激活殺傷性T細胞。因此，他們可以殺死細胞

of them inside the humers of our bodies. So it's responsible for that humoral response.

被感染了的病毒。因此，如果是不為這些東西

And the helper T cell is also going to activate the killer T cells. So they can kill the cell

要不是因為輔助型T細胞，我們將不會那麼幸運。可悲的是，輔助型T細胞

mediated, or excuse me, the cell's that are infected by a virus. And so if isn't for these

會被艾滋病毒或患有艾滋病的人感染。所以你可以了解為什麼

guys, if it isn't for the helper T cells, we're out of luck. Now sadly, helper T cells

這是一個非常糟糕的事情。因為沒有輔助性T細胞，我們沒辦法正常抵抗我們遭受到的感染。

are the cells that are infected by HIV or people who have AIDS. And so you can see why

所以如果你有HIV，你是不會死的。你是會死於一些平常我們能夠抵抗的病毒

that's a really bad thing. Because without the helper T cells we can't fight normal infections.

讓我們再來重新看一次動畫吧

So if you have HIV you don't die of that. You're dying of normal infections that we

這是我們的抗原。請記住，這是我們的侵略者。所以基本上

would fight off. So let me kind of do this in cartoon style. If we were to animate it

我們的巨噬細胞將吃掉它。因此，巨噬細胞會把他抓進去

again. So what we've got here is our antigen. Remember that's our invader. And so basically

然後分泌酶進入它 目的是消化抗原。

what's going to happen is it is going to be eaten by a macrophage. So the macrophage will

然後擺脫它。 但它也是要會留下一點點的碎片。

take it in. It will secrete enzymes into to it which are going to digest that antigen.

抓住這重要的的主要組織相容性複合體。這將把他的形狀帶到其表面，

It will get rid of it. But it's also going to grab on to a little bit of that. It's going

現在，我們有輔助型T細胞。輔助型T細胞將綁住巨噬細胞

to grab on with this major MHC. It's going to take it's shape out to its surface and

它的要感應抗原的形狀。

now we have helper T cell. What's helper T cell going to do? Helper T cell is going to

現在它成為活化的輔助型T細胞。回想一下剛剛的流程圖

dock with that macrophage. And it's going to sense the shape of that antigen. It's now

他會哪裡去了呢？它可以激活巨噬細胞。但更重要的是

going to become an activated helper T cell. So thinking back to that flow chart just a

它會激活B細胞。現在，我們已有一個激活的B細胞。這將激活

second ago, where does it go next? Well it can activate macrophages. But more importantly

殺傷T細胞。現在通過克隆選擇(株落選擇)，它基本上是他們要做無性繁殖

it's going to activate B cells. So now we've got an activated B cell. It's going to activate

因此我們將會有一大堆的活化B細胞。

killer T cells. And now through clonal selection it's basically, they're going to make clones

然後還會有一大堆的活化殺傷T細胞。所以想想看

of themselves. We're going to have a whole bunch of activated B cells. We're going to

這裡上面將是體液反應。這裡下面將是細胞的介導反應

have a whole bunch of activated killer T cells. So now, thinking about it, this on the top

所以基本上我們抵抗這些抗原

is going to be the humoral response up here. And this down here is going to be the cell

我們將抗體黏到它身上，做上記號，所以巨噬細胞可吃掉它，摧毀它

mediated response. And so basically we can fight those antigens out here in the humers

我們還稍微滅活他們。但是如果你看這裡，這殺傷性T細胞

of the body. We do that by sticking antibodies to it so macrophages can eat it, break it

綁住我們身體內已經被抗原感染的細胞。

down. We also inactivate them a little bit. But if you look down here, that killer T cell

然後它會分泌酶進入它，把他摧毀。因此就是把他殺死

is docked with a cell inside our own body that's already infected by an antigen. And

所以基本上我們所做的是我們殺了抗原

so it's going to secrete enzymes into it that are going to break that down. So it's going

然後，我們已經殺死被感染的細胞。因此，這需花一點時間

to kill that. And so basically what we have done is we've killed them in the humers or

但是這將是你的免疫反應。而且他是針對那特定的抗原。

in the fluids of the body and then we've killed cells that are infected. And so this takes

在有那特定的抗原之前，我們不會產生抗體。

awhile. But it's going to be your immune response. And it's specific to that antigen. Until we

來討論感冒了，因為我現在感冒了，現在基本上會發生什麼事是

get that specific antigen, we're not going to produce the antibodies for it. So let's

該病毒會在我的身體內開始繁殖

talk about a cold, because I'm getting a cold right now. So basically what happens is you're

它會花我一點時間來製造Ｂ細胞和殺傷Ｔ細胞

exposed to the cold right here. The virus is going to start reproducing inside my body

所以會有一段滯後時間，但基本上我要去

and it's going to take me a little while for me to start building memory, excuse me, B

製造一大堆的抗體和效應T細胞。所以它們在我體內的數量將提高

cells and killer T cells. And so there's going to be a lag time but essentially I'm going

這段時間是我感覺自己感冒了。

to produce a whole bunch of antibodies and effector T cells. So that's going to increase

這是我的感覺到我自己我感冒了，但真正發生的事情是

inside my body. And this time right here is where I actually feel like I have a cold.

我的身體讚爛病毒抗戰病殺死它們。所以說如果我在未來再碰到相同的感冒

So this is me feeling like I have a cold, but really what's happening is it's my body

那麼在未來我會再接觸到它。但由於

fighting and killing off all the viruses. And so let's say I get exposed to that same