During the COVID-19 pandemic and increased demand of plasma donors, almost all of us have now read about the eligibility criteria of donating plasma. Going through it, one common question that came up in the minds of almost everyone was: Why women with a history of pregnancy can not donate plasma?

Let’s dive into the basics first and figure it out.

What are antigens and antibodies?

An antigen is a foreign substance (usually harmful) which triggers an immune response. An antibody is a glycoprotein that is formed by white blood cells in response to fight the antigen.

What is a blood group antigen?

These are the molecules found over the surface of red blood cells in the blood of a person which determine the blood group of a person. While these are ignored by the person’s own immunity they may be seen as foreign material when introduced to another type of blood group. In response to this foreign material, antibodies are formed as an immune response of the person to who the blood has been introduced.

What is so specific about the blood of a woman who has been pregnant?

When a fetus is growing in the womb, it gets genetical composition from mother and father both. If the fetus receives a particular set of HLA (known as Human Leukocyte Antigen), it may be seen as a foreign substance by the mother’s immune system. In response to this, HLA antibodies are formed in the mother’s womb.

Why not in COVID patients specifically?

When affected with the SARS – COVID virus, the lungs are already compromised. Transfusion of HLA antibodies may further intensify the damage.

Is it harmful to have HLA antibodies?

No, these antibodies do not impose any sort of risk to the mother herself. But it may be harmful when transfused into certain blood groups. The HLA antibodies can cause a rare but serious complication in the recipients known as Transfusion Related Acute Lung Injury (TRALI).

Why specifically plasma donation is restricted?

Plasma along with the salt, enzymes and water carries antibodies in it. When solely plasma is getting transfused, the quantity of HLA antibodies is more as compared to transfusion of whole blood or red blood cells.

Is there some way of knowing if you are HLA positive or not?

Yes, via HLA testing. A sample of your blood is taken. The plasma is separated from the rest of the components in the blood. The plasma is then mixed with different HLA antigens. If the HLA antibodies are already present in the plasma, they react with HLAntigen and give a positive result.

Also read: https://aceyourlifestyle.com/frequently-asked-questions-about-donating-plasma/

If tested HLA positive, can you ever donate?

When tested HLA positive, it is not advised to donate platelets or plasma. You can still donate whole blood or red blood cells as the red cells prepared from your blood contain very little plasma.

Read more about this topic here: https://theprint.in/health/why-women-in-india-who-have-ever-been-pregnant-cant-donate-plasma-for-covid-patients/464729/