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Have you ever thought about why blood donation is so vital? Every 2 seconds a blood transfusion is required making it essential to donate blood. Blood transfusions save lives for a variety of reasons, including surgery, after an accident, and in the treatment of chronic illnesses such as cancer. However, no blood can be given to just anyone. Blood is unique in its own way, and failing to recognize this can result in a fatal response during a blood transfusion.
A Quick Brush Up
Because blood must transport various items throughout the body, it is made up of several components: plasma, red blood cells, white blood cells, and platelets. Despite the presence of red blood cells, white blood cells, and platelets in the plasma, not everyone has the same blood type.
The ABO types and the Rh factor are the two main groups that distinguish blood types. Both of these groups depend on the presence or absence of specific antigens on red blood cells. Depending on the antigen found on the surface of the red blood cell, the corresponding antibody in the plasma will be formed.
To review, an antigen, also known as an immunogen, is a substance that causes the body's immune response. In other words, it causes diseases or allergic reactions. An antibody, also known as an immunoglobulin, is a type of blood protein that is produced in response to a specific antigen. An antibody shields the body from the antigen, preventing it from causing harm to the body.
ABO Blood Types
There are generally four types of blood in the ABO blood type system: A, B, O, and AB. These blood types are distinguished by two types of antigens called antigen A and antigen B. Furthermore, our blood types are inherited by our biological parents just like any other trait in the body.
A Group
The A blood type has only the A antigen on its red blood cells and lacks the B antigen. As a result, the B antibody is present in the plasma of people with blood type A, but the A antibody is not. Because antibodies fight off antigens, if the A antibody is present in the plasma, it will destroy the red blood cells with A antigens on them, so the body will produce B antibodies instead.
B Group
Those with the B blood type are thought to be the diametric opposites of those with the A blood type because their red blood cells contain the B antigens but lack the A antigens. Similarly, A antibodies are present in the plasma surrounding red blood cells but not B antibodies, as B antibodies would destroy the red blood cells. As a result, bodies with blood type B will only produce A antibodies.
AB Group
The AB blood type is distinct in that it has both A antigens and B antigens on its red blood cells. The plasma surrounding the red blood cells cannot contain A or B antibodies because the antibodies produced by the body in the plasma will destroy the red blood cells. Therefore, in an AB blood type, red blood cells have both A and B antigens, whereas the plasma of this blood type contains no antibodies.
O Group
Finally, the O blood type is the opposite of the AB blood type in that it lacks antigens on its red blood cells, but this allows the body to produce both A and B antibodies, which are found in the plasma. In other words, because the red blood cells of the O blood type lack an antigen, if either of the antibodies, A or B, is present, the red blood cells will not be attacked. As a result, the O blood type lacks antigens but possesses both A and B antibodies.
The following is a nice visual representation of the above-mentioned subject:
Rh Factor
The presence or absence of Rh antigens (also known as D antigens) on a red blood cell determines the Rh, or Rhesus, Factor. It can be positive or negative depending on whether or not the Rh antigen is present. We can inherit the Rh factor from our biological parents in the same way that we inherit the ABO group ("letter"). Additionally, the Rh factor is written right next to the ABO group as follows: A+, B-, O+, AB-, and so on.
Rh Positive
The Rh positive blood type is extremely prevalent in the United States and throughout the world. In the United States, nearly 85% of the population is Rh positive. Rh positive refers to the presence of the Rhesus antigen on the surface of the body's red blood cells.
The Rh antigen was passed down through evolution from a common ancestor known as the Rhesus monkey, which carried the antigen. In other words, those who are Rh positive have inherited the DNA that determines D antigens from our ancestors.
Rh Negative
The Rh negative blood type is uncommon as it constitutes only 15% of the population in the United States. This, however, does not imply that there are any health risks associated with being Rh negative. It simply means that no Rh antigens are present on the surface of the red blood cells.
Though an Rh negative person poses no risks to themselves, certain conditions can cause harm to an unborn baby. If the mother's Rh factor is negative and the baby is also Rh negative, there is no harm done to the baby. However, if the mother is Rh negative and her unborn baby is Rh positive, the mother may occasionally produce Rh antibodies. When these antibodies reach the baby, they begin to attack the red blood cells that have Rh antigens on them, causing serious complications for the unborn child. Certain preventable methods, however, have been developed.
Blood Type Compatibility
During a serious medical emergency, knowing the blood type of both the donor and the recipient is critical to avoiding a potentially fatal event in which antibodies attack red blood cells because they contain the corresponding antigen.
To prevent this from happening, scientists have developed a method to determine which blood is compatible with the other by using knowledge of which antigens and antibodies are present in the blood.
ABO Blood Type Compatibility
A Blood Type
An A blood type can donate to:
A Blood Type: A blood type people can donate to another A blood type individual because the antigens on the red blood cells are the same, so the antibodies in the plasma (anti-B or B antibodies) will not attack the donated blood.
AB Blood Type: An A blood type individual can also donate to an AB blood type person because an AB individual's plasma contains no antibodies (no anti-A or anti-B) that could attack the donated blood.
B Blood Type
A B blood type can donate to:
B Blood Type: B blood type individuals can donate to another B blood type individual because the B antigens on the surface of the red blood cells are the same, so A antibodies (anti-A) cannot attack the red blood cells.
AB Blood Type: B blood type can also donate to an AB blood type because an AB blood type lacks antibodies to fight off antigens, so the donated red blood cells are not attacked.
AB Blood Type
An AB blood type can donate to:
AB Blood Type: Because of the same antigen structure, an AB blood type can only donate to other AB people. An AB blood type cannot donate to other blood types because it contains both A and B antigens, which are attacked by the presence of antibodies in all other blood types.
O Blood Type
Finally, an O blood type can donate to:
O Blood Type: Because both the donated blood and the original blood contain no antigens, an O blood type can donate to another O blood type due to the same red blood cell structure.
A Blood Type: An O blood type individual can donate to an A blood type individual because the donated blood's red blood cells contain no antigens that the plasma containing anti-B (B antibodies) can attack.
B Blood Type: Similarly, an O blood type can also donate to a B blood type individual because the donated blood does not have any antigens that the anti-A (A antibody) in the plasma can destroy.
AB Blood Type: Because there are no antigens on the red blood cell and no antibodies in the plasma, an O blood type individual can donate to an AB blood type because the two blood types are compatible.
Rh Blood Type Compatibility
Rh Positive
Those who are Rh positive can only donate blood to those who are also Rh positive. A B+ person, for example, can give blood to another B+ patient but cannot give blood to a B- patient. As mentioned earlier in the post, when an Rh negative blood type is exposed to D-antigens found in an Rh positive person, antibodies that attack the donated blood may form. Hence, unless under dire circumstances, giving Rh positive blood to Rh negative blood types is not a viable option.
Rh negative
Rh negative people, on the other hand, can give their blood to anyone because they lack the D-antigen, which prevents antibodies from forming in the absence of a foreign immunogen. For example, an AB- blood type can donate blood to both AB- and AB+ recipients. As a result, an Rh negative blood type can donate to either positive or negative blood types.
A table summarizing everything discussed in this section is provided below:
Take note of the fact that the AB+ blood type can receive blood from anyone. Because of this, the AB+ blood type is referred to as the universal recipient. In contrast, the O- blood type is known as the universal donor because it can give blood to any other blood type.
The Rarity of Blood Type
Some blood types are more prevalent than others around the world. For example, it is known that blood type O+ is the most common, while blood type AB- is the least common in the United States.
Here is yet another chart showing the distribution in percentages of the prevalence of each blood type in the United States (not worldwide):
There are other blood types other than these 8 which are even rarer than the AB- blood type. For instance, the Rhunll blood type, also known as "golden blood," is found in fewer than 50 people in the world. The Rhnull blood type is distinguished by the absence of any Rh antigens on its red blood cells, including the D-antigen and 50 other antigens normally found on red blood cells. Because it contains no antigens, it is a highly sought-after blood donor for any hematological complications that require the donation of blood.
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