TME 30: Why we cannot receive blood from relatives? GvHD

Introduction

Each individual has unique blood

Blood transfusions are lifesaving procedures, but there's a hidden danger when blood comes from close relatives. It's called Graft-Versus-Host Disease (GVHD), and it's a serious complication that can even be fatal. Let's dive into why this happens and how to avoid it.

What is GVHD?

GVHD occurs when the immune cells (specifically lymphocytes) from the donated blood (the graft) recognize the recipient's body as foreign and start attacking it (the host). This is the opposite of what usually happens in a transplant, where the recipient's immune system attacks the donor cells.

Why Close Relatives?

The risk of GVHD is highest when the blood donor and recipient are closely related (e.g., parent to child, sibling to sibling). This is because their genetic makeup, specifically the Human Leukocyte Antigens (HLA) that identify cells as "self" or "foreign," are more likely to be similar. When the donor lymphocytes see the recipient's HLA as a close match to their own, they may not recognize them as foreign and won't be triggered to attack. However, slight differences in other antigens can cause the donor cells to attack the recipient's body, mistaking it for a threat.

Blood from immediate relatives can cause GVHD

Who is at Higher Risk?

Certain people are more vulnerable to GVHD:

• Immunocompromised individuals: People with weakened immune systems, such as those with cancer or undergoing chemotherapy, can't fight off the donor lymphocytes effectively.

• Infants: Their immune systems are still developing.

• People with certain genetic disorders: Some genetic conditions predispose individuals to GVHD.

Symptoms of GVHD

GVHD symptoms vary depending on the severity, but they can include:

• Skin rash

• Fever

• Diarrhea

• Liver damage

• Jaundice

Prevention is Key

The good news is that GVHD is preventable. Here's how:

• Irradiation: Exposing the donated blood to radiation kills the donor lymphocytes, reducing the risk of GVHD.

• Leukoreduction: Filtering out white blood cells from the donated blood is not that effective against GVHD.

• Alternative donors

• Voluntary blood donation

Click here to read more about different types of blood modifications.

About irradiation of blood

Irradiation of blood components is a crucial process used to prevent transfusion-associated graft-versus-host disease (TA-GVHD), a potentially fatal complication that can occur when transfused donor lymphocytes engraft in the recipient and mount an immune response against the host's tissues. This process involves exposing blood products, such as red blood cells and platelets, to a specific dose of gamma radiation or X-rays. The radiation damages the DNA of any residual white blood cells (lymphocytes) present in the blood components, rendering them incapable of proliferating and causing TA-GVHD. By effectively inactivating these lymphocytes, irradiation ensures the safety of blood transfusions, particularly for immunocompromised patients, neonates, and individuals receiving stem cell transplants. The process does not significantly affect the function or efficacy of the blood components, making it a vital practice in transfusion medicine.

Irradiation of blood is done in a LINAC or a Gamma Chamber equipment

Remember:

If you or a loved one needs a blood transfusion, inform your doctor if there's any chance the donor is a close relative. They can then take steps to minimize the risk of GVHD.

Always consult with your healthcare provider if you have any concerns or questions about blood transfusions.