L05 - ABO Blood Group System PDF

THE ABO BLOOD GROUP SYSTEM Chapter 6 PREAMBLE PowerPoints are a general overview and are provided to help students take notes over the video lecture ONLY. PowerPoints DO NOT cover the details needed for the Unit exam Each studen...

THE ABO BLOOD GROUP SYSTEM Chapter 6 PREAMBLE PowerPoints are a general overview and are provided to help students take notes over the video lecture ONLY. PowerPoints DO NOT cover the details needed for the Unit exam Each student is responsible for READING the TEXTBOOK for details to answer the UNIT OBJECTIVES Unit Objectives are your study guide (not this PowerPoint) Test questions cover the details of UNIT OBJECTIVES found only in your Textbook! 1  KARL LANDSTEINER Opened the doors to blood banking Took blood from himself and 5 others Mixed cells with each other’s serum and observed reactions. First forward and reverse group typing ABO SIGNIFIC ANCE One of the most important Blood Group Systems Causes major transfusion problems with cell incompatibility The only blood group system that has antibodies to antigens that are ABSENT from their RBC’s 2  ABO TESTING: FORWARD AND REVERSE GROUPING Forward grouping: Using known sources of reagent antisera to detect antigens on a person’s RBC’s Anti-A and Anti-B Reverse grouping: Using known sources of reagent RBC antigens to test for the person’s ABO group antibodies Reagent cells A1 and B FORWARD TYPING KNOWN ANTISERA + UNKNOWN PATIENT CELLS 3  REVERSE TYPING KNOWN RBC’S + UNKNOWN PATIENT SERUM GRADING REACTIONS: TUBES 4+: One solid button/Clear background 3+: 2-3 large buttons/Clear background 2+: Multiple smaller buttons 1+: Small clumps Hemolysis: Positive reaction- Complement fixation Negative: Sea of red cells 4  Serum from group A persons will agglutinate group B red cells Antibody to B antigens present R E AC TI O N S (anti-B) Serum from group B persons will agglutinate group A red cells Antibody to A antigens present (anti-A) Serum from group O persons will agglutinate both A and B red cells Antibody to both A and B antigens present R E AC TI O N S Serum from group AB does not agglutinate either A or B red cells Antibody to neither A or B antigens present 5  ABO FORWARD GROUPING (SEE CHART) Patient’s Reaction Reaction with Interpretation of RBC’s with Anti-A Anti-B Blood Group 1 Negative Negative O 2 + Negative A 3 Negative + B 4 + + AB + indicates visual agglutination ABO REVERSE GROUPING (SEE CHART) Patient’s Reaction with Reaction Interpretation of Serum A1 Cells with B cells Blood Group 1 + + O 2 Negative + A 3 + Negative B 4 Negative Negative AB + indicates visual agglutination 6  ADDITIONAL TESTING FOR ABO SYSTEM When ABO Forward and Reverse do not match, it is called an ABO Discrepancy and must be investigated. In this case, we would add O Cell and Auto-control testing. O (RBC) cell testing is used to make sure that there are no unexpected antibodies in the patient serum. In this test, you mix the patient's serum with the O RBC cells and look for agglutination. In a normal patient serum with A, B, AB and O types, they would NOT react with O cells since the O cells do not contain A or B antigens on their cell surface (They only contain the H antigen). If it agglutinates, the patient has an unexpected antibody which is called an alloantibody. Auto-control testing is used in testing to make sure there are no autoantibodies. In this test, you mix the patient's serum with their own RBC's to view for agglutination. In a normal patient serum, there would be no agglutination with their own RBC’s. If it agglutinates, it indicates an autoantibody. NOTE: When an Autoantibody is present ALL cells will agglutinate FREQUENCY OF BLOOD GROUPS (SEE CHART) Phenotype White % Black % Mexican Asian % % O 45 50 56 40 A1 33 19 22 27 A2 7 7 9 Rare B 11 20 10 25 A1B 3 3 3 7 A2B 1 1 Rare Rare 7  Naturally occurring is misnomer Sources of stimulation found in nature ABO ANTIBODY Bacteria PRODUCTION Seeds from plant Pollinating plants Foods ABO ANTIBODIES Unique in that it does not require introduction of foreign red cells by pregnancy or transfusion Not present at birth Titers not detectable until 3 to 6 months Antibody production peaks at 5 to 10 years of age Declines with advanced age After 65 have low titers that may be undetectable in reverse typing 8  OTHER BLOOD GROUPS Some blood groups other than ABO can occasionally cause the production of antibodies without transfusion or pregnancy These antibodies are usually IgM in type They are not consistently present in all patients that have the recessive antigen TESTING FOR ABO Easy to perform Lacking the corresponding antigen serves as confirmation of the forward grouping results Very rare (0.01% or random population) to see complete absence of Anti-A and/or Anti-B in normal, healthy individuals unless, of course, the person has AB blood type 9  Treacherous if wrong ABO group is given Severe if not fatal complications ABO Forward and Reverse typing on all patients, note TYPING reciprocal relationship of antigens and antibody (discrepancy) O is universal donor AB is universal recipient 10  ABO ANTIBODIES IgM – Cold reacting Bind complement (causing lysis) Does not cross placenta Group A and/or B individuals contain Anti-B and/or Anti-A – IgM only (MAJORITY) Anti-B and/or Anti-A – IgM and IgG Anti-B and/or Anti-A – IgM, and IgA Anti-B and/or Anti-A – IgM, IgG and IgA IgM is always predominate Group O individuals contain Anti-A Anti–B IgG anti-A and anti-B are produced far more commonly in group O people than in group A or B people Anti-AB ABO Separate cross-reacting antibody that is a A N TI B O D I E S mixture of IgG and IgM or IgG, IgM and IgA Crosses the placenta more frequently than anti-A or anti-B Produced in response to exposure to A or B cells by transfusion or pregnancy Knowing the amount of IgG anti-A, anti-B and anti-AB allows prediction or diagnosis of hemolytic disease of the newborn (HDN) caused by ABO incompatibility 11  INHERITANCE OF ABO BLOOD GROUPS Inherit one gene from ABO group from each parent Chromosome 9 has one position for the ABO group A or B refer to the phenotypes What is detectable by testing (EXPRESSED) AA, AO, BB, BO, OO denote genotypes What genes are on each chromosome (EXPRESSED AND NON EXPRESSED) Parent Parent Offspring Phenotypes Genotypes Possibility AA X AA A(AA) A XA AA X AO A(AA or AO) AO X AO A(AA or AO) or O (OO) BB X BB B (BB) BXB BB X BO B(BB OR BO) BO X BO B(BB or BO) or O (OO) ABO GROU PS OF TH E OF FS PRING F ROM VARI OUS POSS IBL E ABO M ATING S (S E E CH ART) 12  Parent Parent Offspring Possibility Phenotypes Genotypes Pheno & Genotypes AB X AB AB X AB AB(AB) OR A (AA) OR B (BB) OXO OXO O(OO) AA X BB AB(AB) AXB AO X BB AB(AB) or B(BO) AA X BO AB(AB) or A(AO) AO X BO AB(AB) or A(AO) OR B(BO) OR O (OO) ABO GROU PS OF TH E OF FS PRING F ROM VARI OUS POSS IBL E ABO M ATIN GS (S E E C H ART) FORMATION OF A, B, H ANTIGENS A, B, and H antigens are not fully developed at birth Development begins at 6 weeks of fetal life Not fully developed until 2-4 years old ABO genes do not actually code for the production of ABH Code for enzymes (glycosyltransferases) that add sugars to basic precursor substances on the red blood cell 13  H gene is inherited independently from ABO genes FORMATION OF H is the backbone on which other A, B, H genes are expressed AN TIGEN S H gene is found on Chromosome 19 INTERACTION OF HH AND ABO GENES Inheritance of at least one H gene causes production of enzyme (alpha-2-L-fucosyl-transferase) that transfers a sugar Genotype HH or Hh is possible (h is an amorph of H) Gene is found on Chromosome 19 14  INTERACTION OF HH AND ABO GENES H gene is known as FUT-1 gene 99.9% of population has the H gene “h” amorph is very rare – known as the Bombay phenotype Lacks normal expression of ABH antigens even though person has A and B genes INTERACTION OF HH AND ABO GENES H substance MUST be formed for other sugars to be attached to the RBC (regardless to the inherited A or B gene) Bombay people are devoid of all ABO antigens Bombay types contain Anti-A, -B, -AB & -H They can only be transfused with another Bombay type 15  ABO ANTIGENS 1. The blood group is determined by the terminal sugars on the membranes of their red cells. 2. If neither the A or B gene is present “the O condition” the antigen is H 3. In the presence of the B gene, the sugar galactose is added 4. In the presence of the A gene, the sugar N-acetyl galactosmine is added TERMINAL SUGAR PLACEMENT Anti- Minimal determinant Structure gen structure H B A *: residue could be glucose in case of glycolipids; yellow shade: minimal determinant or core structure; blue arrow: residue added by blood group gene product; examples of type 1 and 2 core structures are illustrated above but they can vary widely, as they can be assembled on at least six possible types of carbohydrate chains; they can reside on a variety of protein or lipid glycan structures containing branches, repeats, etc. 16  F ORM ATI ON OF A, B AN D H SOLUB L E ANTIGE N S ABO Substance In Saliva Grp A B H The presence of ABH soluble O NONE NONE ++ antigens can also be found in all A ++ NONE + body secretions IF they inherit the Se gene. B NONE ++ + Those who inherit the SeSe or AB ++ ++ + Sese gene will secret these * Non-secretors (sese) will have NO ABH soluble antigens in body fluids. substances in saliva If they inherit the sese gene, they will not be secretors. 1911 discovery of 2 types of A antigen A1 and A2 make up 99 percent of all A groups A1 reacts with both Anti-A ABO and Anti-A1 sera SUBGROUPS A2 reacts with only Anti-A sera 80 % of all Group A (or AB) are A1 (or A1B) Note: Anti-A1 sera is NOT the same as A1 cells 17  ABO SUBGROUPS Antigens present on the RBC surface of A1 and A2 are presented in two ways: Group A1: A and A1 antigens Group A2: A antigen only Characteristics of A1 & A2 are found in Table 6-13 (page 129) Reactivity of anti-H antisera or anti-H lectin with the different ABO blood groups (figure 6-11) O > A2 > B > A2B > A1 > A1B ADDITIONAL WEAK A SUBGROUPS A3 – demonstrates a mixed field pattern with anti-A and most of anti-B Ax – will not be agglutinated by anti-A reagent but will agglutinate with anti-AB reagent. 18  WEAK B SUBGROUPS Very rare; less frequent Recognized by variations in the strength of reaction using anti-B and Anti-A,B. B3, Bx, Bm and Bel See table 6-15 for characteristics of the B Phenotypes BOMBAY PHENOTYPE (OH) First reported in 1952 in Bombay, India Inheritance of a double dose of the “h” gene producing the very rare genotype hh. Causes the ABO genes NOT to be expressed (No H gene = No place for sugars to attached) RBCs are void of normal ABH antigens and fail to react with anti-A, anti-B and anti-H Would phenotype as O blood group See Box 6-6 & 6-7 for Bombay Characteristics 19  ABO DISCREPANCY Unexpected reactions in the forward and reverse results of an ABO blood group typing. The forward grouping does not correspond to the results of the reverse grouping OR There is abnormal reactivity present (i.e. mixed field reaction) Discrepancies can be due to technical error Cell suspension too heavy or too light Clerical errors Missed hemolysis Failure to add reagents ABO DISCREPANCY Discrepancies can be due to other factors. Patients age Diagnosis Previous transfusion Medication Previous pregnancy 20  ABO DISCREPANCY: 4 GROUPS Group 1 Associated with unexpected reactions in the reverse grouping due to weakly reacting or missing antibodies Group 2 Associated with unexpected reactions in the forward grouping due to weakly reacting or missing antigens Group 3 Associated with discrepancies between forward and reverse grouping caused by protein or plasma abnormalities resulting in rouleaux formation. Group 4 Associated with discrepancies between forward and reverse grouping due to miscellaneous problems. ABO DISCREPANCY – GROUP 1 Causes of Group I Discrepancies Resolve Group I Discrepancies Newborns: Lack antibodies Elderly: Depressed Antibodies GOAL: Enhance weak or missing reaction Leukemia 1. Incubate at Room Temperature for 15 – 30 Immunosuppressive Drugs minutes & centrifuge 2. If there is still no reaction, ABO Subgroups then incubate at 4° for 15 – 30 minutes & centrifuge Bone Marrow Transplants & Always remember to use an Plasma Transfusions auto and O cell control with reverse typing 21  ABO DISCREPANCY – GROUP 2 Causes of Group II Discrepancies Resolve Group II GOAL: Enhance weak or missing Discrepancies reaction Subgroups of A OR B Leukemia weakened A or B antigens 1. Incubate at 2. If there is still Room no reaction, then Temperature for incubate at 4° for Hodgkin’s disease 15 – 30 minutes & 15 – 30 minutes & centrifuge centrifuge “Acquired B” phenomenon 3. RBC’s can be treated with enzymes and retested with antisera. In the case of suspected “Acquired B”, treat RBC’s with acetic anhydride reacetylates and retest. ABO DISCREPANCY – GROUP 3 Resolve Group III Causes of Group III Discrepancies Discrepancies Elevated levels of globulin-multiple myeloma, Waldenstroms macroglobinemia GOAL: Remove interfering substance Elevated levels of fibrinogen 1. Perform a saline Plasma expanders such as dextran and polyvinylpyrrolidone dilution or saline replacement to free cells Wharton’s jelly in cord blood samples 2. Wash cells 6 – 8 times with saline to alleviate the rouleaux due to Wharton’s jelly 22  ABO DISCREPANCY – GROUP 4 Causes of Group IV Discrepancies Resolve Group IV Discrepancies Cold reactive autoantibodies GOAL: Eliminate spontaneous agglutination Circulating RBC’s of more than one ABO group due to transfusion or transplant 1. Forward: Incubate at 37° for a short time and then wash at 37° 3 times and retype Unexpected ABO isoagglutinins 2. Reverse: Warm to 37° mix and test at 37° Unexpected non-ABO alloantibodies * If forward doesn’t resolve with 1, then treat patient’s cells with DTT. * If reverse doesn’t resolve with 2, try an autoabsorbtion from the serum and then use the absorbed serum to repeat the typing at room temperature. HOMEWORK CHAPTER 6 Review ABO discrepancies and case studies (PGS. 136-145) Review ABO Discrepancy Tutorial online and case studies 23  POSTAMBLE READ the TEXTBOOK for the details to answer the UNIT OBJECTIVES. USE THE UNIT OBJECTIVES AS A STUDY GUIDE All test questions come from detailed material found in the TEXTBOOK (Not this PowerPoint) and relate back to the Unit Objectives 24