Modern Blood Banking Transfusion Practices Chapter 6 The

Modern Blood Banking & Transfusion Practices Routine ABO Testing § § Forward grouping Reverse grouping Routine reagents for ABO testing Requirements for routine ABO testing Copyright © 2012 F. A. Davis Company 6 th Edition

Modern Blood Banking & Transfusion Practices 6 th Edition Routine ABO Testing (cont’d) § Inverse reciprocal relationship between the forward and reverse type § Naturally occurring antibodies § Postulated role of bacteria Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Routine ABO Testing (cont’d) § ABO Antibodies § § Predominantly Ig. M Activate complement Room temperature or colder Produce strong direct agglutination reactions Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Routine ABO Testing (cont’d) § ABO Antibodies (cont’d) § § § Reagent anti-A Reagent anti-B Reagent anti-A, B Monoclonal antisera Polyclonal antisera Considerations for routine blood bank testing Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices Inheritance of the ABO Blood Groups § Work of Bernstein § Inheritance by Mendelian genetics § Codominant expression Copyright © 2012 F. A. Davis Company 6 th Edition

Modern Blood Banking & Transfusion Practices 6 th Edition ABO Genotypes and Phenotypes Genotype Phenotype A 1 A 1 A 1 A 2 A 1 O A 1 A 2 A 2 A 2 O A 2 A 1 B A 2 B OO O BB B BO B Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Formation of A, B, and H Red Cell Antigens § ABH antigen formation results from the interaction of genes at three separate loci (ABO, Hh, and Se). § These genes produce specific glycosyltransferases that add sugars to a basic precursor substance. Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Formation of A, B, and H Red Cell Antigens (cont’d) § Importance of the H antigen § Production of A, B, and H antigens in fetal and adult life Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Interaction of Hh and ABO Genes § Immunodominant sugars confer blood group specificity <Insert Figure 6– 4> Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Interaction of Hh and ABO Genes (cont’d) § Importance of the H gene § Bombay phenotype § Importance of the A gene § Importance of the B gene <Insert figures 6 -5 and 6 -6> § Considerations for the AB blood group Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices Molecular Genetics of ABO § Investigation of ABO alleles, epitope structures, and exons § ABO gene located on chromosome 9 and consists of seven exons § Diversity at the ABO locus Copyright © 2012 F. A. Davis Company 6 th Edition

Modern Blood Banking & Transfusion Practices 6 th Edition Formation of A, B, and H Soluble Antigens § ABH antigens are integral parts of the membranes of various cells § ABH-soluble antigens can be found in all body secretions <Insert Figure 6 -8> Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Formation of A, B, and H Soluble Antigens (cont’d) § Presence in secretions is dependent on ABO and secretor genes inherited. § Nonsecretors are possible. Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition ABO Subgroups § Phenotypes that show weaker variable serological reactivity with the commonly used human polyclonal Anti-A, Anti-B, and Anti-A, B reagents. § Monoclonal typing reagents used routinely. Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition A Subgroups § First described in 1911 by von Dungen § A 1 and A 2 subgroups § Differences between A 1 and A 2 are quantitative and qualitative § A subgroups generally more common than B subgroups Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition A Subgroups (cont’d) § Differences in conversion of H precursor substance among A subgroups § Effects of polymorphism at the ABO locus § Forward grouping reagent (Anti-A) strongly agglutinates both A 1 and A 2 phenotypes § Anti-A 1 lectin reagent used in the differentiation of A 1 and A 2 phenotypes Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition A Subgroups (cont’d) § Anti-A 1 lectin reagent agglutinates A 1 (or A 1 B) cells but does not agglutinate A 2 (or A 2 B cells) § Lectins used in blood banking § Dolichos biflorus: agglutinates A 1 or A 1 B § Bandeiraea simplicifolia: agglutinates B cells § Ulex europaeus: agglutinates O cells (H specificity) and other ABO blood groups depending on the amount of H antigen available Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition A Subgroups (cont’d) § Varying concentration of H antigen among blood groups § Anti-H is occasionally found in the serum § A naturally occurring Ig. M cold agglutinin that reacts best below room temperature § Possible problems in antibody screening procedures § Use of Anti-H lectin Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Weak A Subgroups § Subgroups weaker than A 2 occur infrequently § Most often recognized through an ABO discrepancy (unexpected reactions in the forward and reverse grouping ) § Varying expression of four characteristics § Weak A subgroups can be distinguished as A 3, Ax, Aend, Am, Ay, and Ael Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Weak B Subgroups § Very rare and less frequent than A subgroups § Usually recognized by variations in the strength of the reaction using anti-B and anti. A, B § Result of alternate alleles at the B locus § Five criteria used for differentiation of weak B phenotypes Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Weak B Subgroups (cont’d) § Serologic techniques characterize B subgroups in the following categories: B 3, Bx, Bm, and Bel Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition The Bombay Phenotypes (O h) § First reported by Bhende in 1952 in Bombay, India § Inheritance of a double dose of the h gene, producing the very rare genotype hh § No H antigen made § ABO genes cannot be expressed § ABH antigens cannot be formed Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition The Bombay Phenotypes (O h) (cont’d) § RBCs are devoid of normal ABH antigens and fail to react with anti-A, anti-B, and anti-H. § In RBC testing using anti-A and anti-B, the Bombay would phenotype as an O blood group. Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition The Bombay Phenotypes (O h) (cont’d) § Unlike the anti-H found occasionally in the serum of A 1 and A 1 B individuals, the Bombay anti-H can often be potent and reacts strongly at 37°C. § It is an Ig. M antibody that can bind complement and cause RBC lysis. Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition The Bombay Phenotypes (O h) (cont’d) § Considerations for transfusions § Only blood from another Bombay individual will be compatible § Underlying molecular defect of the Bombay phenotype Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition The Para-Bombay Phenotypes § Rare phenotypes in which the RBCs are completely devoid of H antigens or that have small amounts of H antigen present Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition ABH Antigens and Antibodies in Disease § Associations between ABH antigens and leukemias demonstrating hypogammaglobulinemia , such as CLL § Other leukemias with chromosome 9 translocations Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition ABH Antigens and Antibodies in Disease (cont’d) § Any hemolytic disease inducing stress hematopoiesis (e. g. , thalassemia) § "Acquired B" phenomenon in group A 1 individuals Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition ABO Discrepancies § Unexpected reactions in the forward and reverse grouping due to § Problems with the patient’s serum (reverse grouping) § Problems with the patient’s red cells (forward grouping) § Problems with both the serum and cells Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition ABO Discrepancies (cont’d) § Can appear as extra positive or weak/missing reactions § Must be resolved prior to reporting a patient or donor’s ABO group Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Categories of ABO Discrepancies §

Modern Blood Banking & Transfusion Practices 6 th Edition Resolution of Common Group II Discrepancies § Enhancing weakly reacting antigens with room temperature incubation § Pretreatment of RBCs with enzymes § Acquired B antigen Copyright © 2012 F. A. Davis Company

Modern Blood Banking & Transfusion Practices 6 th Edition Resolution of Common Group III

Modern Blood Banking & Transfusion Practices 6 th Edition Resolution of Common Group IV Discrepancies § Consideration of cold autoantibodies § The patient’s RBCs can be tested with Dolichos biflorus to confirm the presence of an ABO subgroup § Unexpected alloantibodies in the patient’s serum other than ABO isoagglutinins may cause a discrepancy in the reverse grouping Copyright © 2012 F. A. Davis Company