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Blood Banking & Immunohematology - Notice

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Blood Banking & Immunohematology - 1

• ABO and Rh blood group systems are discussed.
• Other blood group systems are also included.
• Pretransfusion and compatibility testing are covered, including HDFN.

ABO & H Blood Group Systems

• The ABO and H blood group systems are the most important.
• Anti-A and Anti-B are IgM antibodies, and are primarily of the IgG class.
• ABO antibodies are detectable in infants 3-6 months after birth, but not until 5 years of age.
• Blood type incompatibility can cause acute hemolysis of RBCs and lead to renal failure/death.
• The ABO locus is on chromosome 9 (or chromosome 19).
• A and B genes are dominant or codominant; O is recessive.
• The O gene is amorphic and does not produce a detectable antigen.

Landsteiner's Rule (1900-1901)

• Relationship between ABO antigens and antibodies.
• Group AB possesses both A and B antigens.
• Group A possesses A antigens.
• Group B possesses B antigens.
• Group O lacks both A and B antigens.
• Group AB lacks ABO antibodies.
• Group A possesses anti-B.
• Group B possesses anti-A.
• Group O possesses anti-A and anti-B.

ABO & H Blood Group Systems

• ABO and H antigens are found in secretions.
• The H gene is needed to form ABO antigens in RBCs and secretions.
• H antigen is a precursor for A and B antigens.
• The amount of H antigen determines ABO blood type: O > A₂ > B > A₂B > A₁ > A₁B.
• H (FUT1) is a-2-L-fucosyltransferase.
• Glycosyltransferases add specific sugars to precursor substances to form A, B, and H antigens.

ABO Discrepancies

• Discrepancies in red cell and serum/plasma results.
• Extra positive reaction or weak/missing ABO antibodies.
• Weaker reactions often indicate a discrepancy.
• Transfusion is sometimes needed when discrepancies are noted.

ABO Subgroups (A1 and A2)

•  80% of group A individuals are A1, 20% are A2.
• Differentiate A1 with anti-A1 lectin (Dolichos biflorus).
• Some A2 individuals will have insignificant reactions with anti-A1.

Bombay (Oh) Phenotype

• First reported by Bhende in 1952 in Bombay, India.
• hh genotype (H-null).
• No production of a-2-L-fucosyltransferase (H-enzyme), no L-fucose, no A, B, or H antigens.
• Phenotype is as blood group O.
• RBCs will not react with anti-H lectin (Ulex Europaeus).

Rh Blood Group System

•  Rh refers to a specific red blood cell (RBC) antigen (D).
• Rh-specific antigens reside on proteins.
• Production of anti-D and other Rh antibodies requires immune stimulation.
• A primary cause of hemolytic disease of the fetus and newborn (HDFN).
• Five antigens make up the Rh system (D, C, c, E, e).
• RH genes are located on chromosome 1.

Wiener: Rh-Hr Terminology

• One gene is responsible for defining Rh; r = absence of D antigen.
•  Presence of C by a' or double prime ("), and E by double prime (").

Rosenfield and Coworkers: Alphanumeric Terminology

• Number assigned to each Rh antigen, with a minus sign (-) for absent antigen.
• Rh1 = D, Rh2 = C, Rh3 = E, Rh4 = c, and Rh5 = e.

Other (minor) Blood Group Systems

• Details about the blood group systems were included.

System with cold antibodies

• Details about this blood group system were included.

Lewis (LE)

•  Details about the structure, interaction, and occurrence of Lewis antigens were provided.

P antigens

• Details about P antigens, and their antibodies were provided.

MNSs

• Details about the MNS system were given.
• Details about the antigens M, N, S, s, and U were included.

Kell System

• Kell antigens (K, k, Kpa, Kpb) were discussed.
• Information about the K cell and its antibodies was provided.

Duffy System

• Information about Duffy antigens (Fya, Fyb) and their connection to malaria.
• Information about the occurrence of Duffy antibodies in different populations was given.

Kidd System

• Information about Kidd antigens (Jka, Jkb) and their connection to HDN was provided.

Lutherans

• Information about Lutheran antigens (Lua, Lub), associated diseases, and frequencies was given.
• Information about the antibodies associated with the antigens was included

Enzyme Treatment of Red Blood Cell Antigens

• Proteolytic enzymes used in the treatment of RBC antigens.

Clinical Significance of Red Cell Antibodies

• Significance classification of antibodies related to different conditions and diseases.

Blood Group Antibodies Related to Infections

• Different blood group antibodies related to different infections.

Human Leukocyte Antigens (HLAs)

• Details about HLA genes and its functions.
• HLA role in tissue/organ transplant, stem cell transplantation, and platelet matching.
• Information about incompatibility causes was given.

Platelet Antigens

• Platelets have protein antigens.
• Antibodies that react with platelets may be ABO, HLA, or platelet-specific.
• Diseases related to platelet conditions were mentioned

Pretransfusion & Compatibility Testing

• ABO/Rh antibody screening and crossmatching.

Antibody Screen

• Screening cells are used to detect antibodies
• Group O donors are used because they lack A and B antigens.
• Unexpected antibodies (other than anti-A and anti-B) are detected using a screening process.
• An unexpected reaction indicates an atypical/unexpected antibody.

Red Cell Dosage Phenomenon

• Heterozygous cells express fewer antigens/quantity compared to homozygous cells.
• Stronger agglutination occurs when a red cell antigen is expressed from homozygous genes

Which pair of cells?

• Questions about cells ideal for blood screening were included.

Antibody Identification Panel Cells

• Procedure for identification of specific antibodies present and their class.
• Antibody panel cells are used for identification when antibody screen is positive.
• Information about autoantibodies and alloantibodies as well as their reaction conditions was included.

Elution

• A method to dissociate antibodies from sensitized cells.
• Useful in cases of positive DAT due to IgG.
• Can help identify autoimmune hemolytic anemia.

Adsorption

• Removes unwanted antibodies from a serum sample.
• Helps isolate specific antibodies during testing.
• Can separate multiple antibodies
• Enables the identification of underlying alloantibodies.

Ig Class Identification (inactivation)

• Dithiothreitol (DTT) and AET to inactive Kell system antigens.
• ZZAP (dithiothreitol and papain) to remove IgG autoantibodies and destroy RBC antigens.

Crossmatch

• A procedure for checking compatibility.
• Major crossmatch: testing patient plasma with donor cells.
• Minor crossmatch: testing patient cells with donor plasma.
• Incompatible reactions/results are noted

Examples of Incompatible Crossmatches

• Different reactions that indicate blood incompatibility.

Types of Graft

• Autograft, isograft (syngraft), allograft, and xenograft.

Antiglobulin (Coombs') Test (AHG)

• Detects IgG or complement proteins attached to RBCs.
• AHG reagents are monospecific and polyspecific.

Preparation of Blood Components

• Various methods and materials used.

Apheresis

• Automated blood separation/collection system.
• Procedure for separating and collecting specific components while returning residual blood to donor.

Adverse Transfusion Reactions

• Classifications/types of reactions.
• Clinical/disease signs related.
• Causes and comments included

Acute Immunologic Transfusion Reactions

• Clinical signs of the reactions and the causes.
• Comments/additional information.

Delayed Transfusion Reactions

• Clinical signs of these reactions and the causes.
• Comments/additional information.

Acute Nonimmunologic Transfusion Reactions

• Clinical signs and possible causes of the reactions.
• Additional comments.
• Different possible causes for the nonimmune reactions.

Determination of feto-maternal hemorrhage

• Procedure to determine the quantity of fetal-maternal hemorrhage(FMH).

Overview of ABO compatibility & blood components for transfusion

• Various ABO types and their compatibility requirements.
• Important information/requirements for transfusion of different components.

ABO Group Selection Order for Transfusion of RBCs.

• Table with selection order of ABO blood types for RBC transfusion for various patient types.

Antibody Typing

• Methodology, reagents, and results for typing.

Frequency of ABO and Rh Antigens

• Frequency of ABO and Rh antigens in different populations.