Health and disease – Immunity Blood groups and blood transfusions Pre-task: Match the German words with the English translation and enter them in the table. English German Spender Verklumpung verklumpen AB0 Blutgruppen Rhesusfaktor Gewebetransplantat Blutübertragung kompatibel, (zusammen-)passend Inkompatibel, unverträglich (starke) Blutung Hämolyse Empfänger Operation übertragen blood transfusion donor recipient tissue transplant AB0 groups rhesus factor haemorrhage surgery to transfuse compatible agglutination haemolysis agglutinated incompatible to clump The transfusion of blood from one person (the donor) to another (the recipient) is the most common ‘tissue transplant’. It has to be carried out carefully because red blood cells carry antigens on their surface membrane, and blood plasma carries antibodies to these antigens. The blood types of the donor and recipient must be carefully matched. This matching can ignore the antibodies of the donor, but must consider the antibodies of the recipient and the antigens of the donor. There are two sets of antigen-antibody interactions to consider. One concerns the AB0 groups; the other concerns the rhesus factor. These interactions, and the effects they have on blood transfusion are outlined in the following. AB0 groups and blood transfusion The AB0 blood grouping is based on: two antigens called agglutinogens, symbolized as A and B, which are genetically determined carbohydrate molecules carried on the surface membrane of the red blood cells two antibodies called agglutinins, anti-A and anti-B, carried in the blood plasma. A blood transfusion may be necessary to make up blood volume following haemorrhage or during surgery. Only compatible blood should be transfused, or agglutination (clumping of red blood cells) and haemolysis (the breakdown of red blood cells) may occur. Agglutinated (clumped) cells may block capillaries and cause kidney or brain damage, or even death. Haemolysed cells ‘leak’ haemoglobin (protein that transports oxygen) so oxygen transport is affected. An incompatible transfusion: blood group B red blood cells of the donor are clumped by anti-B agglutinins (antibodies) in plasma of blood group A of the recipient. Health and disease – Immunity Blood groups and blood transfusions Sketch of a red blood cell showing both A and B agglutinogen (antigen): Antibody anti-A: antibody anti-B: Tasks Use the information from above and… 1. …draw the correct blood cell (showing either antigen A, B, 0 or both A and B) and the correct antibody into the shaded boxes. 2. …conclude which transfusions cause clumping of red blood cells (agglutination). Use the following symbols: (+) blood clumps (-) blood does not clump (Donor) red blood cells of the blood group: (Recipient) Blood plasma of the blood group A B AB 0 A (anti-B) B (anti-A) AB (neither) 0 (both) Use the information in the table and your knowledge and answer the following questions: 3. Which blood group is known as the universal recipient and which is known as the universal donor? Give reasons for your answers. 4. Explain why it is important to screen all donated blood. Extra: Do research on the rhesus (Rh) system of blood grouping. - What is rhesus positive (Rh+) and rhesus negative (Rh-)? - Explain when a blood transfusion from a Rh+ donor to a Rh- recipient can be dangerous? - Explain why it can be dangerous for a rhesus positive baby (Rh+) to be carried by a rhesus negative mother (Rh-). Health and disease – Immunity Blood groups and blood transfusions Use the information from above and… 1. …draw the correct blood cell (showing either antigen A, B, 0 or both A and B) and the correct antibody into the shaded boxes. 2. …conclude which transfusions cause clumping of red blood cells (agglutination). Use the following symbols: (+) blood clumps (-) blood does not clump (Recipient) Blood plasma of the blood group (Donor) red blood cells of the blood group: A B AB 0 A (anti-B) - + + - B (anti-A) + - + - AB (neither) - - - - 0 (both) + + + - Use the information in the table and your knowledge and answer the following questions: 1. Which blood group is known as the universal recipient and which is known as the universal donor? Give reasons for your answers. Universal recipient: AB, since its plasma contains no agglutinins (antigens) to clump donor red blood cells. Universal donor: 0, since its red blood cells do not carry agglutinogens to be clumped by recipient antibodies. 2. Explain why it is important to screen all donated blood.
