MBS121_Practical+06_Lecture_Blood+Typing+_Keyser_.pdf

HUB 124 Practical 5 Blood Grouping © 2012 Pearson Education, Inc. Introduction Antigens = substances that can trigger a protective defense mechanism called an immune response usually proteins, can be...

HUB 124 Practical 5 Blood Grouping © 2012 Pearson Education, Inc. Introduction Antigens = substances that can trigger a protective defense mechanism called an immune response usually proteins, can be other types of organic molecules Surface antigens – on all plasma membranes of your own cells and recognized as ‘normal’ or ‘self’ i.e. ignored by your immune system If a foreign antigen were to enter your body the ‘foreign’ antigens would be recognized and attacked Blood type – determined by the presence/absence of specific surface antigens in RBC plasma membranes (>50 but 3 esp. NB ones) © 2012 Pearson Education, Inc.  Introduction contd. Theses antigens that determine blood type (aka agglutinogens) are: Different antigens On RBCs (and determine your blood type) RBC represented by different Genetically determined shapes NB to consider because of the presence/absence of: Each antibody is specific to one Agglutinins (antibodies) antigen, again represented by different shapes at the binding site = immunoglobulins (remember from the constituents of blood) that are in plasma (the liquid part of blood) and react with antigens (agglutinogens) on the surfaces of foreign RBCs when donor and recipient differ in blood type Hemolysis = the breakdown (lysis) of RBCs; can happen when antibodies from plasma detect foreign antigens on RBCs in blood © 2012 Pearson Education, Inc. Blood Typing Surface Antigens (a.k.a agglutinogens) Are cell surface proteins that identify cells to immune system Normal cells are ignored and foreign cells attacked Blood Types Are genetically determined By presence or absence of RBC surface antigens A, B, Rh (or D) NOTE: blood type is not determined by the type of antibodies (agglutinins) found in the plasma membrane © 2012 Pearson Education, Inc. Blood Typing – check your understanding If agglutinogens are: Antigens on surface of RBCs – i.e. determine blood type Screened by immune system Plasma antibodies attack and agglutinate (clump) foreign antigens → lysis (hemolysis) And agglutinins are: antibodies in the plasma that can attack antigens on ‘foreign’ RBCs Which antigens (on RBCs) and what antibodies (in plasma) would you find in someone with type A blood type? © 2012 Pearson Education, Inc.  Blood Typing Four Basic Blood Types (ABO blood typing) 1. Type A (surface antigen A) RBC 2. Type B (surface antigen B) RBC 3. Type AB (antigens A and B) RBC RBC 4. Type O (neither A nor B) © 2012 Pearson Education, Inc. Blood Typing Blood Plasma Antibodies Type A Type B antibodies Type B Type A antibodies Type O Both A and B antibodies and Type AB Neither A nor B antibodies © 2012 Pearson Education, Inc.  Blood Types and Cross-Reactions © 2012 Pearson Education, Inc.  Blood Types and Cross-Reactions Cross-reaction = when an antibody meets its specific surface antigen, agglutinate and may hemolyze Agglutination = the aggregation of RBCs due to interactions between surface antigens and plasma antibodies RBC Surface antigens Opposing antibodies Agglutination (clumping) Hemolysis In a cross-reaction, antibodies react with their target antigens causing agglutination and hemolysis of the affected RBCs. © 2012 Pearson Education, Inc. Blood Typing – Rhesus factor (+ or -) The Rh Factor RBC Also called D antigen Either Rh positive (Rh+) or Rh negative (Rh−) If you are O+ it means that you have the D antigen on your RBCs BUT the D blood type differs from the ABO types because: Only sensitized Rh− (D − ) blood has anti-Rh (anti-D) antibodies This means that unless you have been exposed to Rh+ (D+) blood no anti-Rh/anti-D antibodies are present in the plasma of someone with Rh− (D − ) blood. © 2012 Pearson Education, Inc.  Blood Typing – ABO+/- system Adding the Rhesus factor gives us not 4 but 8 blood types: Antigens on Antibodies in Blood types _________ ________ Fill in the table. For now, include the anti-D antibodies as you would do for anti-A and anti-B © 2012 Pearson Education, Inc.  Blood Typing – real-life application Cross-Reactions in Transfusions Also called transfusion reaction Plasma antibody meets its specific surface antigen Blood will agglutinate and hemolyze Occur if donor and recipient blood types not compatible RBC Surface antigens Opposing antibodies Agglutination (clumping) Hemolysis In a cross-reaction, antibodies react with their target antigens causing agglutination and hemolysis of the affected RBCs. © 2012 Pearson Education, Inc.  Blood Typing Testing for Transfusion Compatibility Performed on donor and recipient blood for compatibility Depending on the need of the patient different components of blood can be transfused. For now, we will consider packed red blood cells (pRBCs) (aka packed cells) these are RBCs that have been separated for blood transfusion, meaning most of the plasma (and therewith the antibodies in it) have been removed. Without cross-match, type O− is universal donor Can you explain why? © 2012 Pearson Education, Inc.  When considering the transfusion of RBCs these are recipients and these the donors of the Blood Typing blood type given here © 2012 Pearson Education, Inc.  Testing of Blood Types (how is it done) © 2012 Pearson Education, Inc. Figure 19-8 Blood Type Testing Blood Anti-A Anti-B Anti-D type A+ B+ AB+ O– © 2012 Pearson Education, Inc. Relevance of the Rh factor/ D antigen + + + Someone with either of the Rh bloodtypes (A , B , + + AB , or O ) will not have anti-Rh/anti-D antibodies in their plasma BUT - - - - Someone with either of the Rh bloodtypes (A , B , AB , - or O ) will not have anti-Rh/anti-D antibodies either UNTIL they have been exposed to the D/Rh antigen. i.e. if someone is exposed their immune system will recognize this and produce anti-D/anti-Rh antibodies How can someone be exposed though? - + What about a mother Rh mother carrying a Rh fetus? © 2012 Pearson Education, Inc. Hemolytic Disease of the Newborn Rh– mother Rh+ fetus Problems seldom During First Pregnancy develop during a first Maternal blood supply pregnancy, because and tissue very few fetal cells enter the maternal circulation then, and Placenta thus the mother’s immune system is not The most common form of stimulated to produce Fetal blood supply hemolytic disease of the anti-Rh antibodies. and tissue newborn develops after an Rh– woman has carried an Rh+ fetus. © 2012 Pearson Education, Inc.  Hemolytic Disease of the Newborn Exposure to fetal red Hemorrhaging at Delivery blood cell antigens generally occurs during Maternal blood supply delivery, when bleeding and tissue takes place at the placenta and uterus. Such mixing of fetal and maternal blood can stimulate the mother’s immune system Rh antigen on to produce anti-Rh Fetal blood supply fetal red blood cells antibodies, leading to and tissue sensitization. © 2012 Pearson Education, Inc.  Hemolytic Disease of the Newborn Roughly 20% of Rh– Maternal Antibody Production mothers who carried Rh+ children become Maternal blood supply sensitized within 6 and tissue months of delivery. Because the anti-Rh antibodies are not produced in significant amounts until after delivery, a woman’s first Maternal antibodies infant is not affected. to Rh antigen © 2012 Pearson Education, Inc.  Hemolytic Disease of the Newborn Rh– mother In a subsequent pregnancy, the mother is sensitized to the Rh+ fetus. Therefore, the mother’s anti-Rh antibodies cross the Rh+ placenta and attack the fetal red fetus blood cells. Fetus becomes dangerously anemic and will likely die before or shortly after delivery. They look jaundiced due to high circulating bilirubin and their immature RBCs leave the bone marrow prematurely and therefore HDN is also known as During Second Pregnancy erythroblastosis fetalis. Maternal blood supply and tissue The mother’s anti-Rh antibody production can Maternal be prevented if the mother receives Rho(D) anti-Rh immune globulin (injection) in weeks 26-28 antibodies of pregnancy and during and after delivery. These antibodies destroy any RBCs that cross Fetal blood supply the placenta before they can stimulate a maternal and tissue immune response. Because maternal sensitization Hemolysis of does not occur, no anti-Rh antibodies are produced. fetal RBCs In the US, this relatively simple procedure has almost entirely eliminated HDN mortality caused by Rh incompatibilities. © 2012 Pearson Education, Inc. Vocabulary (add more words as you need to) Agglutinins (antibodies)= immunoglobulins in plasma that react with antigens on the surfaces of foreign RBCs when donor and recipient differn in blood type Agglutinogens (antigens) = surface proteins on RBCs whose presence and structure are genetically determined Hemolysis = the breakdown (lysis) of RBCs © 2012 Pearson Education, Inc.