-No environment's static
over time.
The climate will change,
the composition of organisms
that live in that environment
will change.
- As a species,
we've endured massive changes
in our surroundings
cataclysmic shifts.
Our greatest challenge
has always been adapting.
And that means
constantly defending
against all of the threats
we face in the organisms
that live among us.
The immune system, essential
to our survival every second,
is the most complex and least
understood piece of our biology.
And that's because
it's always changing.
As new enemies crop up, this
system meets the challenge
and is transformed.
-The immune system is basically
our body's defense system
against all things foreign.
Not only is our immune system
effective at k*lling.
It's also really effective
at communication, memory,
tagging other cells
when it needs the help.
It's a huge specialized army.
-And to the naked human eye,
it's invisible.
Unlike other systems,
where we can point to a center,
like the heart or the brain,
the immune system is a unique
in that it lives everywhere.
And it is always on the move.
-Survival out here is extreme.
There are days when I feel like
I'm floating
across the landscape
and everything is beautiful.
And then there are other days
where I'm totally wrecked,
exhausted, dehydrated,
very sleep-deprived.
I know full well that at any
point in time I could die here.
My name is Cat Bigney,
and I have been teaching
and consulting in the wilderness
for over two decades.
In many ways, this is my home.
At times I'll spend months
out here
with very limited contact
with the outside world.
To survive in this environment
requires a lot of awareness
and the ability to embrace
hardship and discomfort.
Ouch.
Every time I'm out,
I end up having some sort of cut
or abrasion,
cactus spines in my hands
and feet.
It's just part of it.
-On a microscopic level,
our bodies are in a constant
struggle with the environment.
And the immune system manages
every second of that struggle.
-Our skin has cells
that are very specialized
to create a boundary between us
and the outside world.
-Imagine you're in the midday
desert heat.
You're walking on hot,
loose rocks.
What are you relying on most
to stay alive?
It's your biggest organ,
and it also happens to be the
bedrock of the immune system.
Skin.
-From the moment we are born,
we are exposed to the external
environment and the sun's rays,
but also the extraordinarily
complex environment
that's generated from
our own body's inner workings.
-The outermost layer of our skin
is like a brick wall
that can breathe.
It's made up of cells
that bind tightly together
to keep out UV rays
and foreign objects.
And the oil that sits on top of
these cells is antibacterial,
another first line of defense.
And in our 20 or so square feet
of skin
are tens of millions
of immune cells
that activate
when there's a threat.
But as tight a barrier as it is,
occasionally something
does end up slipping through
the top layer.
Microscopic bugs, or microbes,
can hitch a ride in
on almost anything.
When they do,
there's an immediate reaction.
-On the outside of microbes
there are these little molecules
called antigens.
Our immune system
is specifically trained
to recognize foreign antigen,
friendly antigen.
And if it recognizes foreign,
that's when the cascade
of defense starts.
-Below that top layer of skin
is another one
20 times thicker.
When something foreign gets down
deep enough,
the immune cells sense it
immediately.
They send a signal
inside the body.
Blood will rush
to the damaged area.
White blood cells called
neutrophils will swarm in
and k*ll the microbes by
eating them.
To us, inflammation might seem
like a bad thing.
But really it's just proof
that the immune cells are doing
their job.
-I trust that my body can handle
superficial infections out here.
The desert environment is
pretty forgiving in some ways
because it's so arid and dry,
it is somewhat sterile.
So if I have a scratch
in the desert,
my body will naturally be able
to fight that off a lot better
than if I were in
a jungle environment.
-After the infection has been
brought under control,
the body then has to repair
that spot where the microbe
got through.
- Our bodies have
this innate capacity to repair,
and some of our tissues repair
themselves more than others.
Like skin, for example,
is constantly regenerating.
-Even without a breach,
we shed about 40,000 skin cells
a minute,
or 50 million every day.
So when a wound heals,
that outer layer of cells dies
and falls off.
But beneath them are cells
that constantly replenish
the skin above it,
and those new cells have
a memory.
Inflammation from damage
sensitizes those cells,
so the next time around,
they actually respond faster.
Skin, it turns out,
that's been roughed up before
can heal twice as fast.
So after decades
of cactus thorns,
Cat's primary defenses are
way tougher than most of ours.
-I didn't know that survival
was a thing
until I was 19 years old.
I had a very atypical upbringing
and grew up
in a very remote environment,
and many of the things
that people consider
to be survival skills
were part of my everyday life.
It's important
for people to trust
what's going on
inside their bodies
as well as what their body
can physically do
with the outside world.
This is why survival
is important to me
and it's important for me
to teach it.
Panic, exposure, and dehydration
are the number-one K*llers
out here.
So I need to know what resources
are available,
how much water is in the area.
If your skin isn't hydrated,
it can't do what it needs to do.
I've been in situations
where I've been so dehydrated,
I'm begging my body to continue
for the potential
of finding water.
I may be climbing up some huge
feature to look out for water,
just praying
that I can keep going.
Dehydration at a level where
your body doesn't want to work
and you're talking yourself
into every footstep.
-As strong as it can be,
the immune system's ability
to protect us isn't unshakable.
It depends on how healthy
the body is as a whole.
Water is essential
to immune function.
And it's monitored by the brain.
-Thirst is primarily regulated
by a part of the brain
called the hypothalamus.
And the hypothalamus
has receptors
that can sense a concentration
of the blood
and decide whether we need
a little more fluid
to thin the blood out
a little bit
or whether maybe
we're overhydrated
and we don't need to drink
anymore.
The kidneys also play a role.
So like lots of things in the
body, this is a team approach,
with multiple different organs
involved.
-The body is always paying
attention to water
because it's essential
to everything,
especially clearing out toxins.
Fluid is constantly flowing
through us, carrying bacteria
and other toxins to our
lymph nodes to be destroyed.
These grapelike bunches
of immune cells
are little filters that cleanse
our internal environment.
Dehydration backs up the system.
Without enough water,
waste can't be flushed out
as efficiently,
and immune function suffers
which can lead to
an infection.
-Out here, you can consume
quite a bit of water
and still your mouth will be dry
because it's so arid.
It's important to constantly
be monitoring that.
Running water.
This is golden.
I have to boil it
to k*ll any parasites.
So I won't drink it now,
but I'll get some
to bring with me.
-Cat's ability to survive
comes from knowing
how to use natural resources
to her advantage
and understanding the limits
her body can be pushed to.
Over time, some of those
limits have gotten more extreme.
-Your body will adapt
to surviving in these elements
over time.
But initially,
while your body's adjusting,
it's incredibly difficult.
I have been in situations
where I'm in a bad place,
but the most important thing
is that I trust my body.
The desert's an interesting
place in terms of temperature.
It can get really, really hot
during the day,
but at night, the desert
can become very, very cold
because there's nothing
to keep that heat in.
I've literally had
my water freeze during the night
and then been in temperatures
over 100 degrees during the day.
-After years of training,
Cat's body is uniquely equipped
to handle these
massive fluctuations,
through a process called
acclimatization.
And, like hydration,
it involves the brain.
-There is a capacity for
the brain to regulate hormones
that impact
our body temperature,
our basic homeostasis.
-So in sweltering heat
of the day,
Cat's baseline body temperature
is naturally higher.
She'll also sweat more, and
her sweat will be diluted more,
which leaves more salt
inside her body for energy.
And during the freezing nights,
she'll shiver less,
allowing her to retain
more heat.
- Maintaining
a core body temperature
is paramount
in a survival situation.
That's why shelter is essential.
The environment
wants to suck heat from me
while my body's desperate
to gain any heat that it can,
so what I'm doing
is changing the environment
so I've buffered myself
from the landscape.
-It's a constant negotiation
between body and nature.
And survival means trusting
that you can handle
more than you think.
-I've faced many nights
wondering if I would be alive
in the morning,
with heat, with hypothermia,
through monsoons,
flash floods,
through extreme dehydration.
I think that people
are innate survivors.
I wouldn't be here right now
if someone in my past hadn't
been an excellent survivor.
And that's true of everyone
on the planet.
The hallmark of our species
is being innovative and creative
and overcoming and adapting.
But we've lost faith
in that ability.
We've lost faith in our ability
not to conquer nature,
but to live in it.
It's really important
for us to reconnect with nature
because it teaches us something
about ourselves.
-The human body
is often characterized
as being sort of weak, right?
Like, compare ourselves
to predators,
like lions and tigers
or something.
We don't have big, sharp teeth
or claws.
We're not incredibly strong
for our body size.
So when we think about humans
that way, I'm always surprised
by the sorts of situations
that humans can survive.
-Although raw nature feels
more dangerous
the reality is that
every environment on earth
is teeming with threats
that we can't see.
-Our immune system
is incredibly effective
at defending our bodies.
We encounter
thousands of pathogens
or microbes every single day,
from kitchen counters
to doorknobs
to sitting on a subway.
And the vast majority of
the time, we don't even notice.
-But how does our body know
what to do in the first place?
And why is it that some things
make us sick and others don't?
What we do know
is that everyone's immune system
is different
and how it functions is altered
constantly,
starting from the very moment
we're born.
-So we'll say it together.
- You start it. Yeah.
- We'll both say we're twins.
- Okay.
So you start it.
- Hi. I'm Magaly.
- I'm Carolina.
And we're twins.
- Sorry.
-No. Say, "And we're twins,"
and then look at
I see us as two completely
different people,
We don't dress alike.
We don't have the same taste
in, like, outfits or food
or anything like that.
I dress very ranchy.
And she's more stylish.
She's more girly than I am.
She loves to do her makeup
and things like that.
-I like to go shopping.
I like to go to the mall,
go watch movies.
My room's always clean.
Carolina's room is a mess
all the time.
-If I could not go home,
I would not go home.
I would just love to be
at the ranch every day,
almost all the time.
Twenty-four/seven,
I'll be here with the horses.
-When she comes back
from the ranch, she stinks.
Um, everybody tells her
to go shower.
-Every person's immune system
is like a fingerprint.
Even if you share DNA, a house,
or, in the case of twins
a womb.
-People ask a lot, "What do you
think it is, nature or nurture,
that can affect
our susceptibility to disease?"
And the answer is for
a lot of things, it's both.
We can see within twins
with the same genetic material
there are definitely things that
are genetically predetermined,
but they're not fixed.
Think about why people get sick.
If you think about the flu,
tons of people are exposed.
Some people get really sick.
Some people get a little sick.
And some people don't get sick
at all.
And that has a lot to do
with the health of the host,
what I like
to call terrain theory.
And your terrain
is really your immune system.
-Locked into your DNA
are bits of code
that determine things about your
health long before you're born,
like how cancer
runs in the family
or how a genetic mutation
can help predict the likelihood
you'll develop a disease.
That's the only piece of our
terrain that can't be changed.
Then there are parts
of our immune system we get
just before we're born,
from our mothers.
-Both of my parents originated
from Zacatecas, Mexico.
-
-My mom was raised on a ranch
and away from the city.
So if she was sick,
it was an hour or two hours
away from the doctors,
so they had to figure
everything out at home.
Even now, it's very rare
to see her sick.
So I think that me and my mom
are a lot the same.
-When mothers pass down
antibodies to their fetuses,
this is called passive immunity.
And this is really important
to protect their fetuses
and their newborn babies
when their immune systems
are still developing.
-Along with all the nutrients
that a baby gets
from its mother in the womb,
it also absorbs her antibodies.
These chemicals are leftovers
from infections
that she's fought
throughout her life.
And miraculously, she's able
to pass this protection on
to her child
through the placenta
even if the infection
happened decades ago.
A baby won't be immune
to everything,
but enough to keep it safe for
the first period of its life.
After a few months,
those antibodies start to fade
as the baby encounters
different microbes
and learns to fend for itself.
What we encounter and when
is a huge part
of why everyone's immune system
is different.
-The longer I practice medicine,
the more I believe that nature
is less significant than nurture
for most diseases.
And the really great thing here
is that a lot of these factors
are under our control.
-I was raised on a ranch.
We would always be around cows,
pigs, chickens, sheep
you name it.
-During childhood,
our bodies come in contact
with all the microbes
in our surrounding world.
And our immune system
will see this and say,
"I'm gonna remember
that foreigner."
-It's the same as building
a muscle.
If you don't flex it,
it won't get stronger.
When a young body has to defend
against something,
cells release antibodies
that k*ll the threat.
Other cells then remember
how to make that antibody
so that if the same bug
comes back,
it can be k*lled instantly.
These are the same antibodies
that might one day be passed
down to the next generation.
-So the training early on is
the immune system says, "Okay.
This is nothing.
We can just ignore this.
Ooh. This is super serious.
Red alert.
We really need to do something
about this."
And this training seems to be
really essential.
-Kids who spend time in nature
seem to have an advantage.
-I'm part of an escaramuza team.
Escaramuza
I could describe that as, like,
the Mexican rodeo.
It's kind of like a dance
with eight girls
riding on top of a horse.
You're turning, you're spinning
within each other
and things like that.
A horse isn't born
to do all this,
so everybody has to be
super focused
and have good control
of their horse.
It's very rare
for me to get sick.
And if I do get sick,
like, with a cold,
it'll last one or two days.
As to my sister,
she'll be in bed
for like two weeks.
You know, she's
It hits her hard.
-When I was in high school,
I did get sick.
I stayed home for like a month,
I think I had, like,
a respiratory virus.
It was not fun.
-Kids who are not exposed
to enough germs early on
are really at a disadvantage
and are at a higher risk
for developing disease
because their immune system
doesn't know what to do
when it sees something later on.
-As we age, the training that
happens in our immune system
involves a wide range
of different cells
with different jobs.
But there's one type of cell
that carries most of the weight.
-T cells are the powerhouse
cells of our immune system.
They help make antibodies
against other diseases.
They work with signaling
to other parts
of the immune system.
They can k*ll cells that are bad
on their own.
They also can remember things
so they have a memory component
to them, too
to prevent future infections
or diseases.
-Like all blood, these cells
are born in the bone marrow.
Then they migrate
to the thymus gland.
It's here that T cells
go through serious training
and they pick up
different skills.
Some T cells leave the thymus
as assassins.
Others come out as intelligence,
capable of remembering a virus
for fast detection
and fast execution.
Because of all this action,
the thymus is larger in kids,
and it peaks
in our teenage years.
-What I love about being here
the most
is the bonding
with the horses
grooming him, washing him
sweeping, mopping.
By the end of the day,
I'm extremely dirty.
My sweat, the horses' sweat
It's a very messy job,
but I love it.
-I see so many parallels between
the animal kingdom and us.
And I see that
as we differentiate ourself
more and more,
we're actually getting sicker
and sicker.
So I try to look at what's
going on in the natural world
and what animals do.
Horses take dirt baths
because there are
ammonia-oxidizing bacteria
in the dirt
that can neutralize the sweat
and help clean them.
Getting out
and getting sweaty
all the things that seem to work
so well in the animal kingdom,
I think work really well for us
as humans.
-Exposure to animals can give
the young immune system a boost.
But it's a double-edged sword.
Animals are also the source
of some of our most
devastating diseases.
-Zoonotic diseases
come in many shapes and sizes,
and some are really,
really creepy.
What happens is you have
an animal host
and then something
that transmits it to a human.
It could be, like, a spider
or a mosquito.
This represents
a huge public-health threat
that could get a lot worse
in the future.
-The bubonic plague, malaria,
swine flu, Zika, COVID-19
Many of our
most lethal outbreaks
can be traced to wildlife.
And how close we live to animals
and to each other
plays a huge role.
That's something that
wasn't true for our ancestors.
-If you look at foraging people
or hunter-gatherers and stuff,
the significance of infectious
disease is relatively low.
Today you have
a lot of individuals
that live in very large groups
that are in close proximity
and often interacting
with each other.
Then that does breed
conditions for pandemic disease.
-As our population grows,
outbreaks are becoming
more frequent.
If hindsight is 20/20,
what can we learn from those
who faced past plagues
and lived to tell the tale?
-I had a sense of being
out of my body.
I was feverish,
had joint aches and pains,
copious vomiting and diarrhea.
I didn't realize how sick I felt
until my mother came to
the isolation center to see me
and she said I looked like
I was a zombie.
My name is Adaora Okoli.
I'm a medical doctor entrusted
in infectious diseases,
and I survived Ebola in 2014.
- Viruses cause
millions of deaths every year,
but most of them
come from diseases
that we are familiar with,
like the flu or HIV.
So when a disease
that's been lurking quietly
in an obscure cave
suddenly jumps to a human
and starts to spread,
it's cause for alarm.
Especially if it happens in
a place with limited resources.
-Growing up in Nigeria,
I fell in love with medicine
and the idea of helping people.
A lot of people really didn't
have access to healthcare.
If you were in
an emergency situation
and you didn't have the money
to pay,
you couldn't see the doctor.
I felt that, you know, being
a doctor would to be on the side
where I could be actually able
to help people.
When I finished medical school,
I started working
as a medical officer.
And it was during that time
that the Ebola outbreak struck
in West Africa.
-The Ebola virus has already
k*lled over 3,000 people
across West Africa.
- A growing number
of health workers
are falling victim
of the disease,
adding yet more pressure to
an epidemic the WHO has called
the most severe
acute public-health emergency
in modern times.
-Although deadly outbreaks
end up being remembered
as epic battles,
every major epidemic that has
brought humanity to its knees
can be traced back to something
imperceptibly small.
-There are some pathogens
which are really aggressive
or dangerous,
and a lot of it has to do with
their mechanism of action
or how they attack our bodies.
-A cell is, you know,
most simply speaking,
the basic unit of life.
It's the smallest functional
unit that life can be.
You could argue that viruses
are a little smaller.
-A virus is this little
biological agent
that has one central goal
To get inside of cells,
reproduce itself,
and then spread to another host.
And along the way,
it can cause a lot of damage.
-Viruses emerged from the ether
about 1.5 billion years ago.
And the fact that
they've been around so long
means they're really good
at what they do.
When a virus enters
a host cell
it hijacks it, causing it
to spit out copy after copy
of new virus particles
that burst out of the cell
into the bloodstream.
A virus doesn't just want to
colonize that single host.
It wants to spread
through populations.
-What made the 2014 outbreak
of Ebola widespread
and so dangerous is people
were contracting the disease
without even knowing it.
And by that time, there were
land crossings happening
between Guinea, Liberia,
Sierra Leone,
and the disease
built a community base
and was spreading before
any alarms went off.
-And that type of growth
gets out of hand quickly.
Say you start
with one sick person.
If that number doubles
every three days,
you're gonna end up with
67 million infections
in under three months.
-On the 20th of July 2014,
I was working in
a private hospital in Nigeria,
and a Liberian diplomat
was wheeled into the hospital
with mysterious symptoms.
And when I saw him in bed,
he had his IV bag
right next to him.
So the first thing I did
was pick up the IV bag
and put it back on the stand.
And that might have been the
route of entry into my system.
Twenty-four hours later,
I got a call.
The patient had tested positive.
He had Ebola.
And 24 hours after we had
the result,
the patient was found dead
in his bedroom.
At that point, the fear was more
than we could handle.
It could be any of us
the next day.
-Ebola is an incredibly
infectious disease.
That means that in every drop
of infected fluid,
there are millions
of viral particles.
So if you come into contact
with someone who has it,
it takes almost nothing
to start an infection.
-Shortly after that, I started
to have joint aches and pain,
sore throat, loss of appetite.
Yeah, I was feverish,
I had vomiting and diarrhea.
And I thought, "This is it.
This is really it."
-A virus like Ebola
is extremely lethal
because Ebola
is specifically designed
to evade our immune system
and even mess with
cell signaling in our bodies.
It basically can hijack a ride
throughout our lymphatic
and bloodstream,
infect our bodies,
and it's way too late
when our immune systems finally
pick up on what's happening.
-Ebola's as*ault is merciless.
It attacks the
gastrointestinal tract,
causing diarrhea
and dehydration.
It attacks the kidneys,
which make it more difficult
for the body to produce plasma.
And finally,
the virus releases proteins
that damage the lining
of blood vessels,
which then start to leak.
That's why this disease has
a reputation of causing victims
to bleed from every orifice.
The blood-vessel damage leads
to a drop in blood pressure,
multiple organ failure
follows
then death.
- I was led
to the isolation center.
It was a dark room.
It was an abandoned building
that hadn't been used for years.
Every Ebola patient has a moment
of denial
because nine out of ten people
who have Ebola die.
What are the odds
that I would be the one
out of ten who would survive?
But I was using my clinical
knowledge at the time
as a doctor.
What kills people is
when they lose so much fluid
and their system becomes
overwhelmed with the virus,
which has replicated.
That's when they die.
So I thought to myself,
"I have to really drink
this oral rehydration solution."
I had a bottle in my hand
every time.
Even when I was asleep,
I had a bottle right next to me.
Just in case I vomited,
I could replace my fluids.
I could only hope that my immune
system was strong enough
to fight the virus.
-Even on its last legs, our
immune system keeps fighting.
T cells hone in
on Ebola-infected cells.
They bind to the surface
and release toxins
that travel through the cell's
membrane and k*ll them.
Other cells fire
chemical missiles
in the form of antibodies
to stop the virus in its tracks.
As the immune systems gain
the upper hand,
the body's systems
come back online.
And damaged tissue starts
to heal.
-Most people who survived
usually got better
after seven days or so,
and so it was a matter of time.
After five days,
I noticed that my symptoms
were starting to get better.
Fourteen days later,
my blood sample tested negative.
And that was It was
the happiest day of my life.
It was like being born again.
It was a rebirth.
-The Ebola outbreak in 2014
was eventually
brought under control
when we had international
efforts to understand
quarantining people
who were affected
and help prevent the spread
of future cases.
-And that's because what
we think of as Ebola's strength
is actually its weakness.
It's so deadly that victims die
before infecting enough people
for it to spread widely.
The thing about viruses
is that they actually want you
to stay alive.
A virus like COVID-19
is ultimately more lethal
because its victims stay alive
long enough
for it to spread like wildfire.
But the really terrifying
pandemic is likely yet to come.
-It's starting to seem as though
we're having emergencies
after emergencies
and we are seeing
the same things replicate,
the same things happen.
Viruses do not wait.
- In the future,
we could see a virus
that is as lethal as Ebola
and as contagious as COVID-10.
For Dr. Okoli,
her firsthand experience
with the horror of Ebola
caused her to shift focus
towards fighting
future epidemics.
-Since surviving Ebola,
I came to New Orleans
training in internal medicine
at Tulane University.
Hi. Good afternoon.
- Hi.
- I'm Dr. Okoli.
What brings you to the hospital
today?
-I've been having a dry cough,
and it's been coming in
at night.
-I have shifted my focus
towards infectious disease
and global health advocacy
specifically looking at how
we can reduce the burden
of infectious diseases
in low-income communities.
We're in an age now
where viruses do not respect
geographical locations,
they do not respect race,
they don't respect age.
We're in a world and a time
when people are mobile,
and all it takes is one person
to hop into a plane
and fly thousands of miles away.
It's no longer them and us.
We're all in this together.
-The destruction from an
epidemic can have ripple effects
across continents
and generations.
But given how many bugs
are floating around in nature,
these events
are still pretty rare.
In fact,
there's a lot more danger
potentially lurking
within our own cells.
-Something that's just starting
to become understood
is why does the immune system
sometimes attack our own bodies
instead of threats
that come from outside?
Why is it that our immune system
is not good
at recognizing cancer?
Why do our own cells
sometimes go off script?
-The immune system has to
constantly strike a balance
between k*lling intruders
without damaging the body
in the process.
And when the threat
comes from our own cells,
that job gets even harder.
So now the cutting edge
of immune science
is a quest to understand
how we can harness
the power of the immune system
when it's our own bodies
who are the enemy.
-The only thing I remember
is going into the hospital,
them putting me to sleep,
and then waking up
to needles and tubes
and machines all around me.
I just remember my mom crying
on the side of the bed
and saying, like,
"You have cancer."
And to an 8-year-old, I wasn't
really sure what cancer is.
My name is Milton Wright.
I'm 26 years old, and I'm
a three-time cancer survivor.
I'm an active person.
I am usually boxing
or kickboxing
or going out for jogs.
And growing up,
I just ran around all day
around the neighborhood,
playing football.
When I was about 8,
I just started having
intensive pains.
And I just wasn't able to walk
anymore,
wasn't eating, wasn't drinking.
My weight was down
to my 2-year-old little sister
when I was 8.
Obviously something was way off.
I was diagnosed with leukemia,
a cancer that forms
in the bone marrow
and spreads out
through your blood,
destroying your cells
in your body.
-Our DNA is really
just a molecule.
It's not perfect.
It's prone to getting damaged
over time.
And if the DNA in our cells
get damaged,
then they lose their ability
to perfectly divide.
- Our cells come
with an internal clock
that tells them
when to divide and grow
and when to slow down and die.
But occasionally
a switch gets flipped
that says, "Keep dividing.
Don't stop."
When cells don't die as planned,
they crowd out
and k*ll healthy cells
disrupting the body's
complex balance.
When that happens, it's
the immune system that steps in.
In fact,
every day, your immune system
snuffs out the spark of cancer
without you ever knowing it.
The irony of leukemia
The sad irony
is that sometimes these
cancer-fighting cells go rogue.
White blood cells
in the bone marrow
start to divide unceasingly,
disrupting blood production
and causing
a system-wide breakdown.
-They ended up immediately
putting me
into a three-and-a-half-year
chemotherapy treatment.
Chemotherapy is gonna break the
body down no matter who you are.
It doesn't matter
if you're built like Mike Tyson.
Like, it it doesn't matter.
It can get to a point
where the chemo itself
is worse than the cancer.
-I'm Rebecca Gardner.
I'm an associate professor
at the University of Washington
and a pediatric oncologist.
Historically,
the way we've treated cancer
is we have developed
chemotherapies,
which target cells
that are growing quickly.
They're effective
at treating cancer,
but they're not specific,
meaning that they will target
a lot of your healthy tissues
as well.
And in kids, that's a big issue
because a lot of their cells
are growing quickly.
And so chemotherapy
can have devastating
long-term consequences.
-After finally being
in the clear, when I was 12,
you get back to normal life
as much as possible.
But then I relapsed
when I was 15 years old.
And I relapsed again
when I was about 20 years old.
A third time is pretty much
like that's it.
You're not gonna make it.
After all that happened,
the doctor came back in,
and she was like,
"We have this study
where we use your immune system
to fight off the cancer."
-The concept of immunotherapy
sounds very sci-fi.
At the heart of it,
it's a very simple idea.
Our immune system is designed
to protect us.
The issue is that cancer usually
comes from your own body,
and so your immune system is not
educated to recognize it as bad.
So immunotherapy is really
exploiting your immune system
to recognize your cancer cells
as being bad.
-Cancer is a cellular disease,
and each of those cells have
their own intelligence.
Interacting with our bodies
on that level,
as ecosystems
composed of trillions of cells,
I think can open up
a whole new way to view health
and disease
that is much more nuanced.
- A century ago,
scientists realized
they could treat cancer
by intentionally triggering
their patient's immune system,
like by injecting them
with a bacteria or a virus.
Now gene-editing technology
is allowing us
to educate the immune system
on the level of DNA
to target cancer with a new
and extreme precision.
-We felt like Milton was a good
candidate for this treatment
because he'd gotten chemotherapy
a couple times
and each time,
his leukemia came back.
Any time a treatment is new,
you're guarded.
You think, "Well, even though
all of this stuff looks good,
we're just not sure
if it's actually gonna work."
But Milton was like, "Okay.
Sounds good. Where do I sign?"
-You kind of go in blind,
but it's that or, you know,
nothing, so
- In Seattle,
he was the second patient
that we had ever done this for.
-Milton's immunotherapy began
with his T cells
being extracted from his blood.
The DNA of the cells
was then edited.
Imagine it's like changing
someone's eyes
from blue to brown.
In this case, they changed
the surface of the T cells
so that the cancer cells
would recognize them,
bind to them, and be k*lled.
The mutated T cells
were then injected
back into Milton's bloodstream
and unleashed.
-A couple days after that,
I started getting
flu-like symptoms.
They were like, "Yes!"
-To confirm the immunotherapy
is working,
doctors look for fevers,
aches, and nausea.
These symptoms are caused
by chemical signals
the immune system sends
to rally the troops.
Inside Milton's body,
his reprogrammed immune cells
were on the offensive,
attaching to
and k*lling his leukemia.
-I think it took three months.
Then just one day they came in.
They were like, "Good news.
It's gone."
They were like,
"You're officially cancer-free."
-You look at Milton,
who had really been failed
by chemotherapy.
We came up with
this new therapy,
and we were able to do it.
We were able to get him
into remission.
Hey, hey!
- Hi again.
I'm surprised you're out
of work, out of the office.
- I know.
It's amazing.
-What has it been,
like six years now, right?
- Yeah.
-I'm very thankful for her.
'Cause if it wasn't for her,
you know, I would
I would be six feet under.
I was taking like 110 pills
a day or something.
- I know.
Right?
You don't take any medicines
now.
- No.
- And just think.
When you walk by somebody,
they have no idea.
Right now about half the people
who respond stay in remission.
Our hope is we try to stay
one step ahead of everybody.
So, like, "Okay.
This is your trial now.
But if this one doesn't work
for you, we have this next one."
-It feels good knowing
that I can give back
to what the nurses and doctors
gave to me, which was life.
I'm actually working at
Seattle Children's Hospital now.
So I did a full 360,
from being a patient
to now I work with those same
patients that I once was.
-We've learned so much
that we're actually able to use
the immune system
to treat cancer.
And I think when you look
into the future,
that's what the future
of oncology is gonna be.
It's not gonna be chemotherapy
and radiation.
It's gonna be
very precision medicine.
It's gonna be immunotherapy.
- To know that you
can have something
that is not foreign
to your body protect you
and defeat the cancer cells
inside you
just feels empowering.
-Look at what humans have gone
through throughout history
from famine, natural disasters,
disease.
We have this incredible ability
to adapt to our circumstances
and persevere as a species.
I think we're incredibly
resilient.
-Our ability to survive
goes back to the limitless
potential of this system.
-I've developed a really
intuitive sense of trust
that the cells know what to do.
But we have the potential
to amplify
our body's natural ability
to heal
to move past repair
of the body
and think about the next level,
which is true healing.
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01x04 - Defend
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Diverse personal stories from around the world reveal how lives, passions and goals are facilitated by the human body's various complex systems; narrator Jad Abumrad.
Diverse personal stories from around the world reveal how lives, passions and goals are facilitated by the human body's various complex systems; narrator Jad Abumrad.