{♫Intro♫}
Our immune systems are incredible disease-fighters,
thanks in no small part to proteins called antibodies.
Their job is simple: grab onto things your body wants to get rid of, and only those things.
This act alone can be enough to prevent a virus from infecting a cell,
or stop a toxin from working.
And even if not, it flags the problem so your immune cells know what they need to deal with.
In fact, antibodies are so powerful that doctors and scientists use them a lot—to
detect specific molecules, tackle diseases, and even treat snakebites!
And they have the potential to do much, much more.
Antibodies are also called immunoglobulins, and they’re Y-shaped proteins with sticky tips.
They’re made by a special kind of white blood cell called B lymphocyte or B cell.
And your body has billions of different B cells in it.
So right now, you’re capable of making billions of unique antibodies.
That’s why your immune system can fend off so many different attackers.
Though, you aren’t producing all those antibodies at once.
Most of your B cells are “immature”, which means they’re just kind of sitting
around with the special antibodies they produce embedded in their outer membrane.
They wait this way until something sticks to one of those antibodies.
That tells the B cell there’s something out there for its antibody to grab!
So it “matures” and starts ramping up production.
We call that “something” an antigen,
no matter what it is — a bit of a virus, a toxic protein, whatever.
Like, nowadays, we use the sticking power of antibodies in pregnancy tests!
Animals, or, more recently, cells are used to make antibodies which
bind to the hormones that signal pregnancy.
And those are the detection part of your at-home pregnancy test!
Similar tests exist for things like drugs and pathogens.
Now, especially when it comes to using antibodies to fight disease,
it’s important to note that antigens are small.
That’s because the sticky part of an antibody is only a few nanometers wide.
Meanwhile, the viruses that infect us tend to be one or two
orders of magnitude larger — and bacteria are even larger than that!
So a single pathogen has many potential antigens, or places where different antibodies could attach.
Some of those antibodies may be more effective than others
at actually stopping the pathogen from causing harm.
We call those neutralizing antibodies… because they neutralize things.
But neutralizing or not, once antibodies are floating around in the blood,
their sole job is to stick to their antigens.
That way, if nothing else,
other immune cells can spot them and destroy whatever they’re attached to.
Now, once your body’s dealt with a problem,
some of the B cells that were called to arms become memory B cells.
Essentially, they go back to waiting, but the body is
extra careful to make sure they stick around in case the offender shows up again.
This is how vaccines work!
The only real difference is that, to generate those memory B cells,
they use part of a pathogen or a weakened one in place of a full-on infection.
But sometimes, the process of ramping up antibody production is too slow or not robust enough.
And it's thanks to those cases that scientists and
doctors first figured out how to use antibodies as medicines.
Antibody-based medicines only really became a thing at the end of the 19th century.
One of the biggest breakthroughs happened in 1890, when two scientists set out to find
a treatment for diphtheria — a bacterial disease that was killing a lot of people.
These particular bacteria release
deadly toxins that can kill a person before their immune system can clear the infection.
Now, at the time, no one knew about antibodies. That wasn’t a term yet.
What they had figured out was that animals could develop a resistance to toxins.
They then showed that whatever it was that made them resistant
could be found in the fluid part of their blood.
So they tried giving this fluid, called serum, to other animals.
And it saved those animals from an otherwise deadly dose of the toxins.
The next logical, if risky, step was to try the same thing in people.
So, the team injected the diphtheria toxins into horses,
waited a bit, and then took some of their blood and removed the actual blood cells.
The resulting serum was then transfused into human patients with the disease.
And the treatment was so successful that it won the first ever Nobel Prize
in Physiology and Medicine in 1901!
Around that time, scientists tried the same kind of thing to treat snakebites.
Much like diphtheria toxins, by the time the body ramps up
antibody production to neutralize snake venom toxins, it’s often too late.
So scientists invented antivenoms: the cleaned-up serum from animals injected with venoms.
And they work by boosting the amount of venom-neutralizing antibodies in a person’s blood.
That said, there is a catch to using other animals to make antibodies:
these treatments also tend to contain other proteins from the animals.
And when our immune system sees those, they can trigger
a separate immune response — one that can cause nasty side effects or be life-threatening.
One way around this is to use convalescent plasma.
It’s essentially the same sort of antibody-packed serum, but from people.
Since the blood is human, there’s less likelihood of a bad reaction.
And in the early 20th century, convalescent plasma was used for
all sorts of diseases — including, famously, the global flu pandemic of 1918.
Then, it somewhat fell out of favor, because antibiotics became a thing.
It’s always considered an option, though. Like, we tried it for MERS,
SARS, ebola, and most recently, COVID-19.
But by and large, antibody-based medicines have moved beyond using actual blood.
That’s because, in 1975, antibody researchers had another Nobel Prize-winning breakthrough.
They fused a B cell with a rapidly-reproducing blood cancer cell.
That allowed them to make lots of copies from that B cell — and,
in turn, a large, pure sample of the cells’ antibodies.
This was the beginning of monoclonal antibody treatments, which are now
all the rage in medicine.
Remember: the immune system doesn’t just make one type of antibody per invader.
It makes tons of different ones, some of which are better than others.
With blood-based treatments,
you’re stuck with whatever antibodies happen to be in there in whatever concentration.
But monoclonal methods allow you to produce lots of a really good antibody,
so the medicines are more potent and have fewer side effects.
The first therapeutic monoclonal antibody
was approved in 1986 to stop kidney transplant patients from rejecting their new organ.
And as of January 2020, just under 80 other monoclonal antibody drugs have been approved
in the US, including ones for cancer, rheumatoid arthritis, Crohn’s disease,
psoriasis, migraines, and asthma.
We’ve been tapping into the incredible power of antibodies for over a century.
And in that time, we’ve gotten better and better at making them.
Nowadays, the hardest part is finding a great antibody to mass produce.
And that’s where a lot of the research is focused now.
Unfortunately, we’re out of time! So if you want to learn more about that,
you’ll have to wait for another day.
Like… tomorrow! Because this is just the first of three episodes in our mini-series on antibodies!
Tomorrow’s episode will dive into how scientists find and create
the best monoclonal antibodies for use in medicines and things like pregnancy tests.
Then, in our last installment, we’ll talk about what the future
of antibody-based technologies might look like.
We hope to see you tomorrow! And if you want to make sure you don’t miss an episode,
be sure to subscribe and ring that notification bell.
{♫Outro♫}