| ABO antigens | <haematology, immunology> A system of genetically determined antigens (proteins) located on the surface of the erythrocyte. The presence of these specific antigens gives a blood its unique properties. Because of the antigen differences existing between individuals, blood groups are significant in blood transfusions, maternal-foetal incompatibilities (erythroblastosis foetalis), tissue and organ transplantation. (27 Sep 1997) |
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| ABO blood group | <haematology> The major human blood type system which describes the oligosaccharide glycoprotein antigens found on the surface of human blood cells. According to the type of antigen present, a person may be assigned a blood type of A, B, AB or O. A second type of antigen, the Rh factor, renders a positive or negative blood type. The ABO blood group system is important because it determines who can donate blood to or accept blood from whom. Type A or AB blood will cause an immune reaction in people with type B blood and type B and AB blood will cause a reaction in people with type A blood. Conversely, type O blood has no A or B antigens, so people with type O blood are universal donors. And since AB blood already produces both antigens, people who are type AB can accept any of the other blood types without suffering an immune reaction. (04 Jul 1999) |
| ABO haemolytic disease of the newborn | Erythroblastosis foetalis due to maternal-foetal incompatibility with respect to an antigen of the ABO blood group; the foetus possesses A or B antigen which is lacking in the mother, and the mother produces immune antibody which causes haemolysis of foetal erythrocytes. (05 Mar 2000) |
| ABO incompatibility | <haematology> A type of blood incompatibility, found rarely. Transfusion reactions may occur as a result of such incompatibility. (27 Sep 1997) |