Blood grouping 2022.pdf

Blood Grouping Mahinda Kommalage  ILOs At the end of the lecture, you will be able Students should be able to 1. explain the basis of blood grouping. 2. state the main blood groups that are routinely tested in blood banks in Sri Lanka and other (minor) blood group systems. 3. describe the i...

Blood Grouping Mahinda Kommalage  ILOs At the end of the lecture, you will be able Students should be able to 1. explain the basis of blood grouping. 2. state the main blood groups that are routinely tested in blood banks in Sri Lanka and other (minor) blood group systems. 3. describe the inheritance of ABO and Rh systems. 4. Describe measures taken to prevent transfusion reaction. 5. List the complications of blood transfusion with reasons.  Blood types Membrane of red blood cell contain blood group antigens - agglutinogens Several types - 30 commonly occurring antigens & hundreds of rare antigens. Blood types Most important – ABO system Rh – also important Less important - MNSs, Lutheran, Kell, Kidd  ABO system 4 major blood groups. A – antigen A B – antigen B AB – antigen A & B O – no antigen Found in other tissue – Kidney, liver, lungs. ABO Agglutinins/Antibody Antibody against RBC antigen – agglutinins. Antibody develop after birth due GIT bacteria/food start 2 to 8 months after birth maximum titer at 8 to 10 years No antibody development against antigen present in own cells. IgM and IgG immunoglobulin Inheritance of ABO system Inherited as mendelian allelomorphs. Two genes - one on each of two paired chromosomes.  Prevalence of the different blood types O - 47% A - 41% B - 9% AB - 3% Rh blood group system Rh factor named for rhesus monkey. Only found in RBC. C,D,E (and more) antigen – Most important is D. Rh positive mean antigen D present. 85% Caucasians, 99% Asians are Rh positive.  Rh blood group Rh negative person can produce anti-D antibody when expose to antigen D. (Compare with ABO system….) Anti-D antibody will not develop without expose antigen D. To develop anti-D (Sensitization) need transfusion from other person from fetal blood to mother (Anti-D belong to & capable of crossing the placenta)  Rh blood group Development of anti-Rh antibody is slow process, reaching maximum concentration about 2 to 4 months - Sensitization. In the first exposure, those transfused cells that are still circulating in the blood can be hemolyzed but usually mild. On subsequent transfusion of Rh-positive blood into to sensitized person can make immediate and as severe as a transfusion reaction Transfusion reaction Cells (antigen) from donor will react with recipient antibody. Transfusion reaction Incompatibility make clumps/agglutinates. Agglutinins several binding sites IgG type 2 sites IgM type 10 sites One antibody can bind several antigen. Can plug in small blood vesicles and cell will be destroyed by macrophage or physical distortion. Transfusion reaction Antibody from donors not make problem due to dilution. Can be immediate haemolysis. Delayed haemolysis – late develop antibody and 7-12 days. Can results jaundice. Can be from minor reaction to death.  Transfusion reaction Immediate reaction is due to activating the complement system. Immediate hemolysis is less common than delayed hemolysis Because high titer of antibodies required and different type of antibody, mainly the IgM required.  Transfusion reaction List the complications Haemolytic reactions – Immediate/ Delayed (read!!) Anaphylactic reaction - Allergy Hypothermia (cold storage) Hyperkalaemia - potassium concentration increases during storage Transfusion-related acute lung injury – immunological damage Hemochromatosis (iron overload with repeated transfusion) Clotting abnormalities (after massive transfusion) Blood borne Infections – HIV, Hep B, malaria Transfusion reaction AB type – ‘universal recipients’ O type – ‘universal donors’ But always need cross match.  Blood typing Before giving a transfusion – need to know blood type of recipient & donor. blood typing red blood cells are separated and diluted with saline mixed with anti-A agglutinin and anti-B agglutinin mixtures are observed under a microscope Clumped — “agglutinated” Blood cross matching Direct reaction of two blood - recipient & donor. Help to avoid possible miss match due to other blood group.