What’s my blood type?
In conjunction with World Blood Donor Day yesterday, we take a look at the importance of your blood group.
I FINALLY tested my blood type in school during a health screening. They told me that I am A positive. How many blood types are there?
It depends on the classification you use.
Most people commonly use two types of classifications: the ABO blood group classification and the Rhesus blood group classification.
So, our blood types are usually classified according to both these systems.
There are actually 35 different blood group classifications that have evolved over time!
How are these classifications made?
Take your red blood cells. They are spherical cells that carry oxygen and nutrients to your entire body.
But they also have 30 different substances on their surfaces that make up all sorts of blood group antigens.
Your blood type is determined by one of the many possible combinations of these antigens.
Over 600 different blood group antigens have been documented, which are utilised in different combinations in the 35 blood group classifications.
Nevertheless, we usually use the ABO and Rhesus classifications, as they are the most commonly-accepted ones, so as not to complicate matters, especially when it comes to blood donation.
Some rarer blood group types are linked to certain diseases.
For example, if your blood type lacks a certain antigen called the Duffy antigen, you will be resistant to certain species of malaria.
What is the ABO classification?
In this classification, there are two antigens in your red blood cells called antigen A and antigen B.
There are also two antibodies called antibody A and antibody B, which are present in your blood serum.
The type of antigen(s) you have determines your blood group, as follows:
Antigen A – Blood group A
● Antigen B – Blood group B
● Both antigen A and antigen B – Blood group AB
Neither antigen A nor antigen B – Blood group O
When you have a certain antigen, you will usually have the opposite antibody present.
For example, if you have antigen A, you will have antibody B.
If you have both antigen A and B, you will have no antibodies.
And if you have no antigens, you will have both antibodies A and B present.
Why are these antibodies important?
It is important to know that these antibodies exist because this is the basis of blood transfusion.
Blood transfusion is safe for you as long as the donor’s blood does not contain antibodies against your blood antigen.
Otherwise, the antigen and antibody will “fuse together” in a reaction called agglutination, which will cause a transfusion reaction and possibly result in the person going into shock.
If you are blood group A, you will have antigen A and antibody B.
Antibody A will agglutinate antigen A.
So, only a donor’s blood without antibody A will be safe for you.
Therefore, you can only receive blood from donors who have blood group A or O.
People with blood group AB can technically receive blood from all other blood groups.
And people with blood group O can only receive blood from other people with blood group O.
But it gets more complicated because we also have to take into account the Rhesus classification!
What is the Rhesus classification?
The Rhesus system actually has 50 antigens!
But the most important antigen you have to remember is the D antigen, because it is the one most likely to provoke an immune response when you transfuse the wrong blood type.
You are either D-positive (meaning you have the D antigen), or D-negative (meaning that you don’t).
Usually, this is written as just “+” or “-”.
Combine this with the ABO classification, and you have the eight blood group types that we commonly use today:
● OPeople with the O- blood group can donate blood to anyone. They are called universal donors.
But those with the AB+ blood group cannot donate blood to anyone except other people with AB+ blood. They are called universal recipients.
Is my blood type for life, or do people change blood types over time?
Most people have the same blood group for life.
But in rare circumstances, you can change your blood group if an antigen is added or suppressed.
This happens when you have a bone marrow transplant, especially from a donor with a different blood group.
Eventually, you will convert to your donor’s blood type.
Dr YLM graduated as a medical doctor, and has been writing for many years on various subjects such as medicine, health, computers and entertainment. For further information, e-mail firstname.lastname@example.org. The information contained in this column is for general educational purposes only. Neither The Star nor the author gives any warranty on accuracy, completeness, functionality, usefulness or other assurances as to such information. The Star and the author disclaim all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
During blood donation drives, a chart like the one in this filepic, is used to determine a person’s blood type by seeing which antibody reacts with the person’s antigens.