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Lecture 28
Transfusion Medicine I
Question | Answer |
---|---|
What are the possible genotypes for blood type A? | AO or AA |
What are the possible genotypes for blood type B? | BO or BB |
What is the structure of H antigen? | L-fucose—D-galactose—n-acetyl-D-glucosamine—D-galactose—n-acetyl-D-galactosamine |
What is the structure of A antigen? | n-acetyl-Galactosamine is added on the end of H-antigen |
What is the structure of B antigen? | n-acetyl-glactose is added on the end of H-antigen |
(T or F) Individuals with BB or BO genotype make the same number of B antigen sites. | True. |
(T or F) Indivudals with AA or AO genotype make the same number of A antigen sites. | True. |
(T or F) Individuals with the AB gentoype will make fewer of each blood group antigen than individuals who are A or B phenotype. | True. |
Which blood type has the most H antigen than other blood group phenotypes? | Blood type O |
What is the most common blood type in the United States? | Blood type O |
Which blood type is the least common in the United States? | Blood type AB |
When are antibodies to ABO antigens first appear? | By 6 months of age |
(T or F) ABO antibodies are only formed after exposure to incompatible red blood cells. | False. ABO antibodies are formed without the individuals ever haveing been exposed to incompatible red blood cells. |
What subtype of naturally occuring antibodies aganist incompatible red cell antigen predominant in individuals with A or B phenotype? | IgM |
What subtypes of naturally occuring antibodies aganist red cell antigens are found in individuals with O phenotype? | Mixture of IgG and IgM |
(T or F) The mortality rate of ABO incompatibility depends upon the amount of incompatible blood recieved. | True. 25% in patients who receive over 500 mL of incompatible blood and 44% in patients receving more than 1000 mL of incompatible blood. |
What type of hemolysis occurs with tranfusion with incompatible red cells? | Complement-mediated intravascular hemolysis |
An assay performed to determine the phenotype of the patient's red cell using IgM antibodies against A and B antigens. | Forward grouping |
What is reverse grouping of a blood sample? | An assay where the patient's serum is reacted aganist A and B red blood cells to make sure that the reciprocal antibodies are present. |
What antigen do Rh positive individuals possess? | D antigen |
What is the inheritance pattern of the D antigen? | Autosomal dominant. The absence of D antigen is due to a deletion in the Rh gene. |
(T or F) D antigen antibodies occur naturally in Rh negative individuals without exposure to Rh positive blood. | False. Unlike ABO antibodies, synthesis of D antibodies by Rh negative individuals occurs only upon exposure to Rh positive red cells either by transfusion or pregnancy. |
How is D antigen typing determined on a blood sample? | A patient's red cells are reacted against anti-sera containing anti-D antibodies. |
What is the antibody screen performed by the blood bank? | It is performed to determine if the serum of a patient contains any potentially clinically significant red cell antibodies other than A or B. 15 antigens are tested. |
How is the antibody screen performed? | 2 or more group O red cells that possess all of the 15 antigens are mixed with the patient's serum. Agglutination or hemolysis will occur when the anti-human globulin is added if clinically significant RBC antibody is present. |
What is the crossmatch performed by the blood bank? | It is performed on every unit of blood ordered. The RBC from the unit to be transfused is mixed with the serum of the patient to detect any incompatibility missed by the antibody screen. |