Section 3 Blood Group and Transfusion

1. Section 3 Blood Group and Transfusion Agglutination, hemolysisand the transfusion reaction

2. Blood Groups • Based on the types of special antigens on the surface of the red blood cells • Two particular groups of antigens are more likely than the others to cause blood transfusion reactions. • ABO system • Rh system,

3. ABO Blood • classifications depend on the presence or absence of the agglutinogens (antigens) on the surface of the red cell membrane.

4. Group B Agglutinogens • Two antigens- type A and type B occur on the surface of the red blood cells. • These antigens are called agglutinogensbecause they often cause blood cell agglutination, causing blood transfusion reactions Group AB Group A Group O

5. Agglutinins • The agglutinins are gamma globulin in the plasma. • When type A agglutinogen is not present in a person’s red blood cells, antibodies known as anti-A agglutinins develop in the plasma. • when type B agglutinogen is not present in the blood cells, antibodies known as anti-B agglutinins develop in the plasma. • type O blood, although containing no agglutinogens,doescontain both anti-A and anti-B agglutinins. • Finally, type AB blood contains both A and B agglutinogens but no agglutinins.

6. Major types of ABO blood group • The bloods are normally classified into four major types, • depending on the presence of absence of the two agglutinogens, A and B

7. ABO blood group • But why are these agglutinins produced in people who do not have the respective agglutinogens in their red blood cells? • Small amounts of type A and B antigens enter the body in food, in bacteria, and in other ways, and these substances initiate the development of the anti-A and anti-B agglutinins.

9. Agglutination and hemolysis in transfusion reaction • When bloods are mismatched so anti-A or anti-B plasma agglutinins are mixed with red blood cells that contain A or B agglutinogens respectively, • agglutinins will make the red cells adhere to each other – agglutination. • The clumps of red cells will plug small blood vessels throughout the circulatory.

10. Group B Group B anti-B anti-B anti-B Group B Group B anti-B

12. Agglutination and hemolysis in transfusion reaction • During the ensuring few hours to a few days, • either physical distortion of the cells or attack by phagocytic white cells destroys the agglutinated cells, • releasing hemoglobin into the plasma, • which is called “hemolysis” of the red blood cells.

13. agglutination • During severe hemolytic reaction, fever, chills and shock may occur. • One of the most lethal effects of transfusion reactions is kidney shutdown, which can begin within few minutes to a few hours. • If the shutdown is complete and fails to open up, the patient die of renal failure.

14. Blood typing Before giving a blood transfusion to a person, it is necessary to determine the blood type of the recipient’s blood and the blood type of the donor blood so that the bloods can be appropriately matched. This is called blood typing and blood matching.

15. Rh Blood Groups Blood Typing, Showing Agglutination of Cells of the Different Blood Types with Anti-A or Anti-B Agglutininsinthe Sera Red Blood Cell Types Sera Anti-A Anti-B O - - A + - B - + AB + +

16. Rh BLOOD GROUP SYSTEM • Rh (rhesus factor) • Is named after the rhesus monkey in which it was found • Rh is an antigen present on the RBC membrane – transmembrane proteins, which may act as ionic channels • 6 types of Rh AG • C,D, E, c, d*, and e (+ 43 other Rh antigens, which are less common) • Antigen D is the most common and potent • Presence of D antigen - Rh+(RhD+) • Lack of D antigen - Rh-(RhD-) • Population data on RhD+ • 85% of Caucasians • 90% of African Americans • 99% of Asians • 100% of Africans

17. Rh BLOOD GROUP SYSTEM: Antibodies • Blood of normal individual does not contain anti-Rh antibodies (with exception of anti-E) • Production of anti-Rh antibodies can be evoked by • Transfusionof Rh- individual with Rh+ blood (only 0.5 ml may suffice) • The presence of Rh+ fetus in a Rh- mother

18. Rh BLOOD GROUP SYSTEM: Typing • Mixing of the blood sample with anti-Rh serum (D AB) • Agglutination – RhD+ • No agglutination – RhD-

19. Rh IMMUNE RESPONSE • Transfusion of RhD+ blood to un-immunized RhD- recipient • No immediate reaction • Sensitization of recipient’s blood to RhD AG - slow formation of anti-RhD AB • Delayed transfusion reaction – hemolysis of the donor’s RBC that still circulate in the recipient’s blood • Transfusion of RhD+ blood toimmunized RhD-recipient • Enhanced transfusion reaction – acute hemolysis

20. ERYTHROBLASTOSIS FETALIS ↑ risk starting from gravida 2 or para 2.

21. Rh+ fetus/RH- mother Some fetal RBC enter the maternal circulation Formation of anti-Rh AB in the maternal blood Some anti-Rh antibodies enter the fetal circulation Hemolysis of fetal Rh+ RBC Gross edema (hydrops fetalis) Hemolytic jaundice, anemia, high reticulocyte count, erythroblasts Bile pigments pass into the brain and are deposited in the basal ganglia → impairment of motor functions Gross edema ERYTHROBLASTOSIS FETALIS (cont.)

22. ERYTHROBLASTOSIS FETALIS (cont.) • Treatment • Replacement of the neonate’s blood with Rh- blood – removal of Rh AB and damaged RBC • Prevention • Administration of anti-D AB to the Rh- pregnant woman who expects RhD+ baby • Destruction of Rh+ RBC, which cross the placenta and enter the maternal circulation • Inhibition of AG-induced AB production by B lymphocytes in the pregnant woman

23. Past exams question Fred's blood type is A, Rh- and Ginger's is B, Rh+. Fred and Ginger have a 4-year-old son who is AB, Rh+. Which one of the following conclusions is correct? a. During the second pregnancy Ginger needs to take anti-D antibodies b. There is no risk to a second child to develop erythroblastosis fetalis c. If the son needs a blood transfusion Fred could provide it safely, but not Ginger d. Fred is not the boy’s father B