How blood is screened for 'clinically important' antibodies This can cause a condition called haemolytic disease of the foetus and newborn, where the antibodies attack and destroy red blood cells, causing anaemia in the developing baby. That's because there's a risk that antibodies generated from an incompatible blood transfusion could pass through the placenta (should she fall pregnant) and into a foetus's bloodstream. It's sometimes called the "universal blood type".Īnd for a woman who may one day have kids, it's especially important to use matched or O negative blood in a transfusion. What is least likely to cause a reaction is O negative blood, which lacks A, B and RhD antigens. If the reaction is severe enough and not treated, it can be life-threatening. Transfusion reactions don't always cause massive problems but can mean symptoms like fever and low blood pressure. Then, if your immune system encounters those antigens again, it might attack and destroy them. Just as your body churns out antibodies to protect against infections, you can also make antibodies against unfamiliar blood antigens. Positive means your red blood cells sport an antigen called RhD. It's a similar story with the positive or negative part of your blood type.
If your blood type is A, you only have A antigens.Antibodies are Y-shaped proteins which recognise and latch onto antigens, should they encounter them again, which the immune system then clears away.įor instance, the A, B, AB or O part of your blood type refers to the presence (or absence) of A and B antigens.If someone is transfused with incompatible blood, the foreign antigens on those blood cells can trigger the recipient's immune system to produce antibodies.
Antigens and antibodies: what's the difference?Īntigens are carbohydrate or proteins found on the surface of all blood cells (as well as body tissues and on surfaces of bacteria and viruses). Red blood cells are usually depicted like dark red cough lozenges with a perfectly smooth surface.īut look closer, and there's a multitude of molecules embedded in the cell's surface, called antigens, that determine your blood type. So which others are important, and how are they changing too? Why do blood types matter? The national blood audit looked at the two blood groups we're most familiar with: ABO and RhD.īut these are just two of 40-odd human blood group systems. Overall, our blood is becoming more positive - that's Rhesus D or RhD positive. The proportion of people with O positive blood (like me) dropped a couple of per cent from 1993-94 to 2019.Īustralia also saw an increase in the rates of people with B and AB positive blood, a reflection of migration from countries such as China and India, where those types are more prevalent. Being part of the substantial slab of the Australian population with O positive blood running through my veins, I was recently surprised to find out I'm a little less common than I was in the '90s.Ī national blood audit by Australian Red Cross Lifeblood researchers found the nation's changing ethnic make-up is mirrored in shifting proportions of blood types.
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