Just one pint of donated blood is enough to save three lives.
The blood you donate is actually sold on the open market and the blood industry is worth
$4.5 billion per year.
But blood saves lives.
If you began donating blood at the age of 17 and donated every 56 days, until you reach
76 years old.
You will have saved more than 1,000 lives.
But not everyone’s blood is the same.
Hollywood movies and TV shows regularly remind us that before someone can undergo a blood
transfusion, medical professionals must find out that person’s blood type and match it
with a suitable donor’s blood type.
But why?
What would happen if you were given the wrong blood type?
What even is a blood type and why do we have them to begin with?
Let’s find out.
There are four major blood types: A, B, AB and O. Blood type is hereditary and which
one you have, depends on your parents.
If both parents have A blood type, the child will most likely have an A blood type as well.
Similarly, B and B-type parents will produce offspring with B-type blood.
However, if one parent is A-type and the other B-type, the child will be AB-type.
Okay that’s all quite simple, but things get trickier when we introduce the O blood
type.
A and B blood types are dominant genes, or “alleles” to be more precise.
Whereas the allele responsible for O blood type in recessive.
This means if one parent has an O blood type and the other parent has either an A or B
blood type, then the child is most likely to have either an A or B blood type.
In order for someone to have an O blood type, both their parents have to have O blood types
too.
Making O blood types extremely rare and highly sought after in the medical field, there’s
also another reason why donors with an O blood type are desired so much, but we’ll get
to that later.
It’s all very well labelling them with letters but what does your blood type actually say
about your blood?
What makes A blood different from B blood?
Well, it all has to do with what type of sugars and proteins sit on the red blood cell.
Antigens are proteins or sugars that attach themselves to the membrane of red blood cells.
An antigen acts as an identifier to your immune system.
There are many different varieties of antigens and each has their own unique signature, a
way of identifying itself to your own immune system.
I’m sure you’ve heard of antibodies, they’re the little armoured knights of our bodies.
Whenever a foreign object, enters our blood stream, the immune system instantly dispatches
antibodies, like flying ninja-monkeys.
They make their way around the body and attach themselves to cells, if they find a cell that
wasn’t created by our own body, such as an evil pathogen, then the antibody exterminates
it.
But how does the antibody know which cells belong to our body and which are foreign intruders?
Well that’s where antigens come in.
Antigens have a unique configuration that our immune system is familiar with, when an
antibody attaches to a cell, it does so by connecting with the cell’s antigens.
If it recognizes the configuration of the antigen it kindly buggers off and leaves it
in peace.
If it can’t successfully attach to the antigen, because it has a configuration that the antibody
isn’t use to, it destroys the cell instead.
It’s kind of like the antigen and the antibody share a unique password, and only by exchanging
that password will the antibody leave that cell alone.
There are two types of antigen, A and B and the combination of those A and B antigens
that sits on your red blood cells, determines your blood type.
Someone who only has A antigens on their cells is said to have an A blood type.
Similarly, having only B antigens means you have a blood type of B. If you have a mix
of both A and B antigens on your cells you have an AB blood type.
People with an O blood type however, do not have any A or B antigens, but they don’t
have O antigens either, because there’s no such thing - they instead, have no antigens.
Because O blood types don’t have antigens on their cells, they are known as universal
donors.
This means their blood can be given to anyone with any blood type and it will be accepted
by the recipient’s body.
This is because an O-type blood cell doesn’t have any antigens, so the recipient’s antibodies
don’t have any way to attach to the blood cell and identify it.
What normally happens when a patient receives a blood transfusion is that the antibodies
are dispatched to latch onto the foreign blood cells and detect whether it has A or B antigens
upon it.
If the foreign antigens match the antigens of the recipients own blood, then the body
accepts the new blood.
For example, a recipient with a blood type of A can only receive blood with A antigens
or no antigens, as is the case with O-type blood.
Similarly, B blood types can only receive blood with B antigens or no antigens.
People of an AB blood type however, are able to receive blood with no antigens, A or B
antigens, or even a combination of both, because their antibodies are setup to recognise and
accept both A and B antigens.
AB blood types are therefore known as “universal recipients” because they can receive any
blood type.
If someone receives a blood transfusion of the wrong blood type and their immune system
rejects it, for example, if an A blood type receives B-type blood, then the results can
be catastrophic.
If you are given the wrong blood type the first thing you will experience is “a feeling
of impending doom”.
Yes, that is actually a genuine, medical symptom.
That feeling of impending doom will also be accompanied by severe flu like symptoms.
The cause of these symptoms is your immune system attacking the foreign blood cells.
Your body’s antibodies will detect that the antigens of the foreign blood do not match
the type of antigens of your own blood cells, and so it kills them.
The attack which ensues upon the foreign blood cells is both quick and aggressive.
When foreign blood cells of a different blood type are being killed off at such a rapid
rate, the dead blood cells can accumulate in the veins and cause a blood clot.
This is known as an “acute hemolytic transfusion reaction” and it can very quickly kill someone.
Because of this, hospitals are extremely careful and blood type mismatches happen very rarely,
but when they do, the resulting fatality rate is high.
If you think that blood types seem rather simple, I’m sorry to tell you, there’s
a little more to it than I’ve been letting on.
So up to now we have four blood types, A, B, AB and O. However, there are actually eight
blood types, at least within the ABO system.
Those are A+, A-, B+, B-, AB+, AB-, O+ and O-.
So where do the positives and negatives come from.
It comes from a third type of antigen, called the Rh factor.
Named after rhesus monkeys, in which it was first identified.
Your blood cells either have the Rh factor antigens or they don’t.
If the Rh factor antigens are present, then you have a positive blood type, if they’re
not present you have a negative blood type.
Rh negative blood may be given to patients with either Rh negative or Rh positive blood
types, providing their primary A, B or O blood type matches, as we talked about previously.
However Rh positive blood will only be accepted by someone who also has Rh positive blood.
I know this complicates things somewhat, but here’s a handy table that shows you which
donor blood types can be accepted by which recipient blood types.
So you can refer to it if you ever find yourself having to give an emergency blood transfusion.
You’re welcome.
In some cases, if a mother with Rh negative blood is carrying a foetus with Rh positive
blood, the mother’s antibodies can cross the wall of the placenta and attack the unborn
baby.
This is a condition known as “Haemolytic disease of the newborn”.
Some cultures believe that blood type actually reflects an individual’s personality.
Just like some people use astrological signs in the West, in Japan your ABO blood type
is believed to hold information about your personality, temperament and compatibility
with others.
Although this is not supported by modern science.
The belief is so strong, that in Japan, you’re highly likely to be asked what blood type
you are when you interview for a new job, or go on a date with a potential partner.
If you’ve ever played a Japanese video game, especially an RPG, you might have noticed
the character descriptions in the game’s manual include the character’s blood type,
right alongside features such as their name, gender and height.
You might think it strange that the game developers have even thought about what blood type the
game characters are.
But blood type-personality association is so strong in Japanese culture, that it’s
considered completely normal.
Although it’s interesting to learn about, there’s no need to keep a card in your wallet
or get a tattoo saying what blood type you are, in case you’re in a near-fatal accident
and need to receive blood.
Because these days, blood type tests are so fast and efficient, that it’s quicker and
more accurate for the doctors to run a test, than to go rummaging through your wallet to
find out your blood type.
The most common blood type is O+; O+ types make up 40% of the population.
Conversely, AB- is the rarest blood type, only 1% of the world are AB-.
Only 9% of the population have the precious and always in need, O- blood type.
If you possess O- blood you should feel quite empowered, because it’s the only blood type
that can be safely given to every human on the planet.