Universal Blood Type Donors and Recipients

AB positive (AB+) and O negative (O-) are considered universal blood types. People who are AB+ are universal recipients, meaning they can safely receive a blood transfusion of any other blood type. O- individuals are universal donors, meaning their blood can be given to people of any blood type.

Having a universal blood type can save a life—either yours or someone else's—in an emergency. Only about 7% of people are O-, and their blood bank donations are in high demand because this type is used most often for those in need of a transfusion.

This article explains how blood typing works. You will learn what it means to be a universal blood recipient or a universal blood donor. You will also find out why blood types need to be compatible, and what happens if they are not.

Blood Types

To understand how universal blood donors and universal blood recipients work, you need to know the meaning of two key terms: antigens and Rh factor.

Antigens

Antigens are a substance that the body's immune system can respond to. Antigens are found on the surface of blood cells. When the immune system detects an antigen that it does not recognize, it will fight it. 

The antigens on blood cells determine how a recipient reacts to a blood transfusion. The presence or absence of antigens helps categorize the different blood types.

In addition to the universal recipient type, there are seven blood types: O positive, O negative, A positive, A negative, B positive, B negative, and AB negative.

The four main blood types indicate whether you have (or don’t have) A or B antigens:

• Type A blood has the A antigen.
• Type B blood has the B antigen.
• Type AB blood has both A and B antigens. This blood type is the rarest.
• Type O blood has no antigens. O negative blood is considered the universal blood donor type because it is compatible with type A, AB, B, and O blood, whether Rh positive or Rh negative.

Rhesus (Rh) Factor

Blood types are described as being positive or negative. This is based on the presence or absence of a protein called the rhesus (Rh) factor. It's often written as "+" (positive or present) or "-" (negative or absent) when noting a person's blood type.

Here's how the Rh factor affects blood donation:

• Rh-negative blood can be given to Rh-negative patients
• Rh-positive or Rh-negative blood can be given to Rh-positive patients 

Since both A and B antigens are present in a person with AB+ blood and it has a positive Rh factor, the recipient does not have antibodies to these antigens and will not reject the blood. That means a person who is AB+ is the universal recipient, as they can get any type of blood.

Your blood type is determined by your genes, which means it's not something that will change throughout your life. However, there have been rare cases of people's blood types changing temporarily when they have certain blood cancers. There have also been rare reports of a patient's blood type changing after they get a bone marrow or organ transplant.

What Blood Types Match?

A person can always receive a blood transfusion from someone with their own blood type. Some blood types can also receive blood from people with certain other blood types. A person with AB+ blood, for example, can receive any blood type, while someone with O- blood can give blood to anyone regardless of type.

Here's a breakdown of recipient blood types and their matching donor blood types:

Blood Transfusion Reactions

A person can have a reaction to a transfusion if they receive the wrong type of blood. An allergic reaction to a blood transfusion is also possible, regardless of a person's blood type.

A hemolytic transfusion reaction is when there is a mismatch between the donor and recipients' A, B, and O blood types. Antibodies in the recipient's blood attach to the donor's red blood cells and destroy them in the recipient's bloodstream, liver, and spleen.

The body's response can cause a person to have a yellow tint to their eyes and skin (jaundice). It also can cause uncontrolled clotting in the bloodstream, shock, and rarely death.

Acute vs. Delayed Reactions

Blood transfusion reactions are divided into two categories: acute and delayed.

• Acute reactions happen within 24 hours of a transfusion
• Delayed reactions come later, and may happen days to weeks after a transfusion

Hemolytic reactions are rare because hospital blood banks type and crossmatch each unit of blood to be given to a recipient.

Allergic Reactions to Blood

It is also possible to have an allergic reaction to a blood transfusion. This type of reaction is not caused by a blood type mismatch—it happens because the recipient's body identifies the donor blood as a foreign invader and destroys the cells.

The symptoms include:

• Fever
• Chills
• Rash
• Itching
  
• Shortness of breath

The symptoms of an allergic reaction often go away in a day or two and can be treated by stopping the transfusion. A person can also be given an antihistamine (like Benadryl) to help with symptoms.

If a person has a severe reaction to a blood transfusion, they may need to have more careful screening for blood in the future to prevent a similar reaction during later transfusions.

Organ Donation

Receiving a blood transfusion is not the only time being a universal blood recipient or universal blood donor matters. It also makes a difference when an organ transplant is needed.

A patient who needs an organ and has AB+ blood can accept an organ from donors of all blood types, just as they can accept a blood donation of any type. However, the process of matching an organ donor with a recipient is more complicated than only matching a blood type.

The organ allocation system is set up so that it's fair to people waiting for a donor organ. This way, people with AB blood don't receive more organs than people with other blood types.

Summary

Universal blood donors and universal blood recipients are unique.

A person with a universal donor blood type can give blood that any person can receive. A person with a universal recipient blood type can get any blood donation, which can be life-saving in an emergency.

If you have the universal donor blood type, you know that giving blood can help a lot of people. That said, donating blood if you can is valuable no matter what your blood type is.

Usually, there is enough donated blood to help anyone who needs it; however, there can also be blood product shortages. Ongoing blood donations keep the supply stocked to help all patients in need.