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Blood Typing

Pearson
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Knowing a person's blood type is important to avoid incompatibility issues during transfusions and pregnancy. In this lab, you will learn the theory behind blood typing procedures. This video will describe how surface antigens on a red blood cell (or RBC) determine blood type; demonstrate how antibodies cause agglutination of red blood cells; and explain how preformed antibodies determine compatibility between blood donor and recipient. Blood type is determined by the presence or absence of a specific glycoprotein on the outer surface of the red blood cell. These glycoproteins are called antigens. The surface antigens that you have are genetically determined. Individuals who have Type A surface antigens have Type A blood. People with Type B surface antigens have Type B blood. It's also possible for individuals to have both A and B surface antigens. They would have Type AB blood. Lastly, Type O blood means that a person has neither A nor B surface antigens. In addition to surface antigen differences, individuals will make antibodies against surface antigens that are not present on their own red blood cells. Antibodies are proteins that have a lock and key recognition for their antigen. This is established by the antigen-binding site on the antibody. For example, healthy people with Type B blood would have anti-A antibodies against the A surface antigen because they don't have A surface antigens. Let's check your understanding. Which type of antibodies will a person with Type O blood have in their blood: anti-A, anti-B, anti-A and anti-B, or anti-O? >> Individuals with Type O blood have neither A nor B antigens on the surface of their red blood cells. Therefore, they would naturally form antibodies against the A and B antigens. The figure on the screen summarizes the antibodies preformed in the plasma for specific blood types. For example, individuals with Type A blood have surface antigen A on their red blood cells as well as anti-B antibodies circulating in their bloodstreams. These preformed antibodies are the reason transfusion reactions occur when there are incompatibilities between blood types. For example, if a person with Type A blood is transfused with Type B blood, the anti-B antibodies in the recipient's Type A blood will bind to the Type B surface antigen of the donor, resulting in agglutination, or clumping, of the Type B blood cells. Widespread agglutination is usually fatal. For this reason, a person with Type A blood can receive only Type A or Type O blood. Notice on the screen that anti-A and anti-B antibodies that are present in the Type O donor's plasma are not included. The anti-A antibodies in the donor's plasma would react with the A antigens on the recipient's red blood cells; thus, packed red blood cells, without plasma, are administered to avoid this reaction. Review the table of compatible blood types shown. Let's check your understanding. Which blood type is considered to be the universal recipient who can theoretically receive all ABO blood types without a transfusion reaction? >> Individuals with Type AB blood can theoretically receive all ABO blood types as the universal recipient. Because Type AB individuals lack both anti-A and anti-B antibodies in their plasma, it does not matter what antigens might be present on the surface of the donor RBCs; agglutination will not occur. Which blood type is the universal donor who can theoretically donate blood to all individuals without causing a transfusion reaction? >> Type O blood is the universal donor. Because Type O individuals lack both the A and B surface antigens, it doesn't matter which antibodies the recipient might have in their plasma; agglutination usually will not occur. The Rh antigen is another surface antigen that contributes to a person's blood type. If people have the Rh (sometimes called D) antigen, they are Rh positive, which is indicated by adding a plus sign to their ABO blood type. The red blood cell illustrated here is Type O positive. If the Rh antigen is not present, the person would be Rh negative, and a minus sign would be added to the blood type. The red blood cell illustrated here is Type AB negative. All ABO blood types can be Rh positive or Rh negative, which amounts to eight different blood types listed on the screen. Unlike the A and B antigens, antibodies against the Rh antigen only appear in the blood for an Rh negative individual who has been exposed to Rh positive blood. Pregnant women must be blood typed to know if they are Rh negative. If a mother is Rh negative, measures must be taken to prevent complications that could arise for a fetus that is Rh positive. The blood typing procedure, as we will see in this lab, requires the observation of agglutination reactions. Note that for demonstration purposes we will be using synthetic blood. Your instructor may choose to use either real or synthetic blood. The results achieved are similar but not identical. Typing with real blood is shown in the photographs. If a sample of blood agglutinates in the presence of a specific antibody, it means that the corresponding surface antigen is present. For example, if a drop of blood is added to the antibodies that are specific for the A antigen, called anti-A antibodies, agglutination is seen; it means that the Type A antigen is present on the surface of the red blood cells in the sample. To determine a person's blood type, we need to test for the presence or absence of each surface antigen (A, B, and Rh) using antibodies specific for each antigen. When we add the blood sample to anti-B antibodies, no agglutination is seen. When we add the blood sample to anti-Rh antibodies specific for the Rh antigen, agglutination is seen. Because there is clumping in the anti-A and anti-Rh wells, the blood tested is recorded as Type A positive blood. Let's check your understanding. Determine the blood type you see here on the screen. Is it Type AB positive, Type O positive, Type AB negative, or Type O negative? >> There is no agglutination in either the anti-A or the anti-B wells, which means that neither the A nor the B antigens are present. There is agglutination of the red blood cells in the anti-Rh well, which means that the Rh antigens are present. In this experiment, you will be testing blood samples. You will be able to use your understanding of blood typing to interpret your results.
Knowing a person's blood type is important to avoid incompatibility issues during transfusions and pregnancy. In this lab, you will learn the theory behind blood typing procedures. This video will describe how surface antigens on a red blood cell (or RBC) determine blood type; demonstrate how antibodies cause agglutination of red blood cells; and explain how preformed antibodies determine compatibility between blood donor and recipient. Blood type is determined by the presence or absence of a specific glycoprotein on the outer surface of the red blood cell. These glycoproteins are called antigens. The surface antigens that you have are genetically determined. Individuals who have Type A surface antigens have Type A blood. People with Type B surface antigens have Type B blood. It's also possible for individuals to have both A and B surface antigens. They would have Type AB blood. Lastly, Type O blood means that a person has neither A nor B surface antigens. In addition to surface antigen differences, individuals will make antibodies against surface antigens that are not present on their own red blood cells. Antibodies are proteins that have a lock and key recognition for their antigen. This is established by the antigen-binding site on the antibody. For example, healthy people with Type B blood would have anti-A antibodies against the A surface antigen because they don't have A surface antigens. Let's check your understanding. Which type of antibodies will a person with Type O blood have in their blood: anti-A, anti-B, anti-A and anti-B, or anti-O? >> Individuals with Type O blood have neither A nor B antigens on the surface of their red blood cells. Therefore, they would naturally form antibodies against the A and B antigens. The figure on the screen summarizes the antibodies preformed in the plasma for specific blood types. For example, individuals with Type A blood have surface antigen A on their red blood cells as well as anti-B antibodies circulating in their bloodstreams. These preformed antibodies are the reason transfusion reactions occur when there are incompatibilities between blood types. For example, if a person with Type A blood is transfused with Type B blood, the anti-B antibodies in the recipient's Type A blood will bind to the Type B surface antigen of the donor, resulting in agglutination, or clumping, of the Type B blood cells. Widespread agglutination is usually fatal. For this reason, a person with Type A blood can receive only Type A or Type O blood. Notice on the screen that anti-A and anti-B antibodies that are present in the Type O donor's plasma are not included. The anti-A antibodies in the donor's plasma would react with the A antigens on the recipient's red blood cells; thus, packed red blood cells, without plasma, are administered to avoid this reaction. Review the table of compatible blood types shown. Let's check your understanding. Which blood type is considered to be the universal recipient who can theoretically receive all ABO blood types without a transfusion reaction? >> Individuals with Type AB blood can theoretically receive all ABO blood types as the universal recipient. Because Type AB individuals lack both anti-A and anti-B antibodies in their plasma, it does not matter what antigens might be present on the surface of the donor RBCs; agglutination will not occur. Which blood type is the universal donor who can theoretically donate blood to all individuals without causing a transfusion reaction? >> Type O blood is the universal donor. Because Type O individuals lack both the A and B surface antigens, it doesn't matter which antibodies the recipient might have in their plasma; agglutination usually will not occur. The Rh antigen is another surface antigen that contributes to a person's blood type. If people have the Rh (sometimes called D) antigen, they are Rh positive, which is indicated by adding a plus sign to their ABO blood type. The red blood cell illustrated here is Type O positive. If the Rh antigen is not present, the person would be Rh negative, and a minus sign would be added to the blood type. The red blood cell illustrated here is Type AB negative. All ABO blood types can be Rh positive or Rh negative, which amounts to eight different blood types listed on the screen. Unlike the A and B antigens, antibodies against the Rh antigen only appear in the blood for an Rh negative individual who has been exposed to Rh positive blood. Pregnant women must be blood typed to know if they are Rh negative. If a mother is Rh negative, measures must be taken to prevent complications that could arise for a fetus that is Rh positive. The blood typing procedure, as we will see in this lab, requires the observation of agglutination reactions. Note that for demonstration purposes we will be using synthetic blood. Your instructor may choose to use either real or synthetic blood. The results achieved are similar but not identical. Typing with real blood is shown in the photographs. If a sample of blood agglutinates in the presence of a specific antibody, it means that the corresponding surface antigen is present. For example, if a drop of blood is added to the antibodies that are specific for the A antigen, called anti-A antibodies, agglutination is seen; it means that the Type A antigen is present on the surface of the red blood cells in the sample. To determine a person's blood type, we need to test for the presence or absence of each surface antigen (A, B, and Rh) using antibodies specific for each antigen. When we add the blood sample to anti-B antibodies, no agglutination is seen. When we add the blood sample to anti-Rh antibodies specific for the Rh antigen, agglutination is seen. Because there is clumping in the anti-A and anti-Rh wells, the blood tested is recorded as Type A positive blood. Let's check your understanding. Determine the blood type you see here on the screen. Is it Type AB positive, Type O positive, Type AB negative, or Type O negative? >> There is no agglutination in either the anti-A or the anti-B wells, which means that neither the A nor the B antigens are present. There is agglutination of the red blood cells in the anti-Rh well, which means that the Rh antigens are present. In this experiment, you will be testing blood samples. You will be able to use your understanding of blood typing to interpret your results.