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We all know we should donate blood, but probably don't as much as we

should. Every year almost 5 million Americans need blood transfusions and

would likely die without them. Approximately 32,000 pints of blood are

used each day in the United States for people who lose blood during operations

or from traumatic injuries. Others need blood transfusions because of ongoing

illness like sickle-cell anemia where they all need transfusions throughout

their lives. The network of blood donation and transfusion in any country

is a hugely vital part of keeping sick or injured people alive and well. This

wouldn't be so complicated if we all had the same type of blood, but we don't. And

some of us have such rare blood types that any injury, any procedure, or any

accident can be life-threatening. Imagine your blood was so rare and so

unique that should you get hurt, almost no one else in the worlds donated blood

would be able to save you. So rare and so valuable that your identity needs to be

concealed to keep a never-ending stream of requests for it at bay. So rare that

scientists would do almost anything to get their hands on a pint of it to study.

For the people who have the rarest blood type in the world, Rh null this is their

reality. It's the world's most dangerous blood type to have because only 43

people in the world are discovered to have it. Meaning if you get hurt,

basically no one else's blood would be compatible with yours. Injuries that

would be serious but treatable for everyone else would probably be fatal

for you. Most of us have probably heard of the usual blood type system, or even

know our own blood type. O+, AB-, A+, O-. This

classification determines who we can donate blood to or receive it from. There

are a total of 33 different classification systems recognized but

most people only need to worry about the two most common ones, the ABO and Rh

systems. The ABO system classifies blood based on the presence of antigens,

antigen A and antigen B. You can have one or the other, both, or neither. Antigens are

glycoprotein markers embedded in the cell membrane and help your immune

system to distinguish between your body's own cells and foreign cells like

viruses or bacteria. In an A blood type the A antigen is found on the blood cell

itself and an A or anti-B antibody is found in the blood serum. In a B blood

type a B antigen is found on the blood cell and a B or anti-A antibody is

found in the serum. Blood type AB has both A and B antigens on the blood cells

and neither of the corresponding antibodies against them in the serum. And

blood type O has neither antigen on the cells but has antibodies A and B in the

serum. When blood is donated, the red blood cells are separated from the

plasma where the antibodies are located through a process called blood

fractionation. This ensures that only the red blood cells get donated and not

their corresponding antibodies since that would cause an adverse reaction in

the recipient. Your immune system will produce antibodies against any blood

antigens you don't have in your own blood. Therefore a person with type A

blood that receives B blood would have an ABO incompatibility reaction. The

anti-B antibodies present in the patient's blood would agglutinate

with the B antigens on the donated red blood cells making the blood cells clump

together and block small blood vessels. The immune system would then attack the

new blood cells and destroy them. It's rare for this to happen but if it does

it is serious and potentially fatal. Transfusion is considered safe as long

as the serum of the recipient does not contain antibodies for the blood cell

antigens of the donor. So this is why if you have type AB blood you're a

universal recipient - you don't have either of the antibodies that would

attack A or B donor blood. However this also means you can only donate blood to

other people who have A B blood. If you have type O blood you're universal donor.

You can give your blood to a A B or O without triggering their

immune system. But this is also why people with O blood can only receive

Type O blood. However there are other antigens that

need to be accounted for beyond the ones and the ABO system before donating or

receiving blood safely. This is where the rhesus system comes in. The rhesus, or Rh

system, is the second most significant blood group system. These are the most

important antigens with the most significant one being the D antigen.

Although there are lots of other Rh antigens RH-D is the most significant

because it's the most likely of the Rh antigens to produce an immune response.

Depending on whether the RH-D antigen is present, each blood type is assigned a

positive or negative symbol. People who are Rh-D negative can only receive Rh-D negative

blood. But people who are Rh D+ can receive either Rh D positive or Rh D negative

blood. The negative blood types, A negative, B negative, AB negative, and O

negative are more rare than their positive counterparts. And while the D

antigen is the most important one in the Rh system there are a total of 60 other

Rh antigens making it the largest of any of the blood classifications. And while

these eight blood types are the most common way of describing our blood, each

of these eight types can be subdivided much further. There are millions of

varieties, each classified according to the exact antigens that coat the surface

of our red blood cells. To know your exact blood type you'd have to write it

out antigen by antigen. Luckily for most of us many of the

antigens we have don't affect our ability to receive or donate blood

because pretty much everyone else also has them. For example more than 99.9%

of people carry the antigen called Vel. So for most of us donating

blood to one another we wouldn't need to worry about this antigen as it wouldn't

trigger an immune response. But for every 5,000 people there's one person

who does lack the Vel antigen who shouldn't receive blood from the other

4,999. Their immune system recognizes the

Vel antigen as foreign and if given Vel positive blood they could have

kidney failure and possibly die. But doctors do screen for as many of these

variants as possible to make sure to find the best match for a blood

transfusion. But sometimes this best match isn't really possible and this is

why the rarer your blood the harder things get. The world's rarest blood type,

Rh-null is called Rh-null because it has none of the 61 antigens present in the

Rh blood system we previously discussed. It is rare enough to have a few of the

antigens in the Rh system missing from your blood but the chances of missing

them all are astronomically small. Doctors call it the golden blood because

for anyone who has any type of rare Rh blood type, missing a few antigens here

or there, the Rh-null blood can be accepted where other more typical blood

types could not be. It has enormous life saving capabilities but for those who

have it it can be a curse. Most of us likely take for granted that if we get

hurt the nearest hospital will be able to sort us out. But if you're one of the

few with Rh-null blood life is inherently more dangerous. You can't

receive blood from anyone else except the 42 other people that exist who have

been found to have the same blood type. And of the people known to have it only

a handful of them are active donors and they're spread across the world. And the

logistics of shipping blood around the world are stupidly complicated.

Bureaucracy and paperwork can hold things up at the borders, which can

create a myriad of issues. Fresh blood has a shelf life of four weeks and it

has to be stored at four degrees Celsius, which is challenging during

transportation, especially to remote areas. This means that any holdup at

customs can render the blood unusable. And some countries have very restrictive

rules in regards to importing blood. The UAE for example won't accept any blood

into the country that isn't from the Gulf states. These types of logistics and

bureaucracy make it very hard for someone with rare blood to get a

transfusion, especially in a sudden emergency when they need the blood fast.

For one Swiss man with Rh-null blood, this meant as a child, he couldn't go to

summer camp or do outdoor sports because his parents feared he could get an injury

with no ability to get a blood transfusion. As an adult he can't travel

to countries without modern hospitals. The only realistic way he can navigate

this danger is to continuously donate blood to himself,

meaning twice a year he donates blood to keep on reserve in case he ever needs it.

And he can't really donate much more than that because Rh-null blood also comes

with some adverse effects. The Rh antigens that most of us have are

thought to play a role in maintaining the integrity of the red blood cell

membrane. Red blood cells which lack Rh antigens have an abnormal shape and an

increased osmotic fragility. This means that red blood cells break down quicker

than they should resulting in a hemolytic anemia. This can lead to

fatigue, shortness of breath, and jaundice and thus makes frequent blood donation

impossible. And because only a handful of people with this rare blood ever donate

it, this places a large burden on those who do when someone else needs this type

of blood. Because Rh-null blood can be donated to anyone with a rare

combination of Rh negatives in their blood type, every once in a while they

may get an urgent call to donate. The Swiss man we mentioned before once had a

call that a newborn baby was in dire need of his type of blood. To save the

baby's life he would need to make his way to the donation center. This meant

taking a taxi to Geneva and taking time off of work, none of which is allowed to

be reimbursed due to the blood donation laws in some parts of Europe. He was able

to help in this instance, but quickly realized that the cost and burden of

donating his valuable blood would ultimately fall on him. Anyone with this

rare type of blood is given the gift of being able to help someone at a time of

need, an ability to help where no one else can. It probably feels pretty

amazing to know you've played a part in saving someone's life. But this also

comes with the unfortunate burden of being, in a sense, on call for your entire

life, should the need for your blood arise. This poses an interesting ethical

question. It's up to you to donate blood at a moment's notice, whether you're in a

client meeting, at your own wedding, or on vacation. At what point does your moral

obligation to help someone else in need begin and end? But for every person who was

otherwise doomed without this donated blood, the importance of it obviously

can't be overstated. And this serves as a reminder that hospitals around the world

rely on the good deed of blood donation to save lives, whether your blood is rare

or not. Since the very first blood transfusions in the 1800s

they have saved millions of lives and played a vital role in shaping our

modern world. In times of peace they've saved citizens from unfortunate

accidents and in times of war have saved the lives of countless wounded soldiers.

During World War II the American Red Cross flew almost two

hundred thousand pints of whole blood from the US to the Allied forces in

Europe. More than fifty thousand pints of blood were needed for the soldiers

fighting during the D-day invasion of Normandy alone. The level of coordination

needed for the collection and transport of this much blood is astounding, and you

can learn more about logistics like this in Real Engineering's new "Logistics of

D-Day" series available exclusively on Nebula, the streaming platform made by

the best educational content creators, like Wendover Productions, Medlife

Crisis, BrainCraft, and our other channel Real Engineering. Nebula is a place for

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