Red cell antibodies

What does this mean?

These antibodies are related to red cells in your blood.  

They are not caused by illness or infection. 

They are not harmful to your health and will not affect your health in anyway, but if you have a blood transfusion, or if you are of child bearing age and may become pregnant in the future they could cause serious illness. 

They are not infectious and cannot be caught by other people.

Why do I need to know about these antibodies?

Red cell antibodies can develop naturally but usually happen after having a blood transfusion or after a pregnancy.  Approximately 1 in 15 people develop an antibody to donated blood and will need to have specially matched blood in future.  

Antibodies are part of your body’s immune or ‘self-defence’ system. They are normally made to attack a substance which is foreign to the body (such as bacteria or viruses). You will always have these antibodies in your blood. 

Your body has made some antibodies which attack red cell proteins. These are not harmful, but if you need a blood transfusion in the future, the donated blood should not contain the red cell protein for which you have an antibody. This is to ensure your body doesn’t react to the transfused blood and make you feel unwell.  

When you are pregnant, some antibodies can occasionally affect your baby. So it is important for doctors who treat you and for the hospital laboratories to know about the red cell antibodies in your blood. 

The transfusion laboratory will have a record of your antibodies and will find suitable blood for you. 

Further information 

If you have questions about this information please speak to your Doctor or Midwife.

With acknowledgement to Oxford University Hospitals NHS Trust for kind permission to use text from their ‘Red cell antibodies - Information for patients’.

Red cell antibodies - patient information leaflet
Review due: May 2026
Version 1