Podcast
Questions and Answers
Which test is specifically used to identify antibodies attached to RBCs in conditions like erythroblastosis fetalis?
Which test is specifically used to identify antibodies attached to RBCs in conditions like erythroblastosis fetalis?
What is the potency order of Anti-Rh antibodies from strongest to weakest?
What is the potency order of Anti-Rh antibodies from strongest to weakest?
Why are Lewis antibodies considered almost always clinically insignificant?
Why are Lewis antibodies considered almost always clinically insignificant?
Which blood type has the highest prevalence in the USA?
Which blood type has the highest prevalence in the USA?
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How are Lewis antigens related to the Le gene and Se gene?
How are Lewis antigens related to the Le gene and Se gene?
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Which type of antibodies is produced after viral infections and can lead to Paroxysmal Cold Hemoglobinuria?
Which type of antibodies is produced after viral infections and can lead to Paroxysmal Cold Hemoglobinuria?
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What is the primary antigen that acts as a binding site for Parvovirus B19?
What is the primary antigen that acts as a binding site for Parvovirus B19?
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Which blood group antibodies are known to not bind complement and can cause acute and delayed Hemolytic Transfusion Reaction?
Which blood group antibodies are known to not bind complement and can cause acute and delayed Hemolytic Transfusion Reaction?
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Which blood group contains the least common allele type associated with its antibodies?
Which blood group contains the least common allele type associated with its antibodies?
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What distinguishes warm autoimmune hemolytic anemia (AIHA) from cold AIHA?
What distinguishes warm autoimmune hemolytic anemia (AIHA) from cold AIHA?
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Which blood group antigens are coded by genes on chromosome 4?
Which blood group antigens are coded by genes on chromosome 4?
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What type of hemolysis occurs when antibodies fix complement in autoimmune hemolytic anemia?
What type of hemolysis occurs when antibodies fix complement in autoimmune hemolytic anemia?
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What is a primary characteristic of Kell antibodies?
What is a primary characteristic of Kell antibodies?
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Flashcards
Coomb’s Test
Coomb’s Test
A test used to detect antibodies attached to RBCs.
Rh Antibodies
Rh Antibodies
Antibodies related to the Rh blood group, most notably Anti-D.
Lewis Blood Group
Lewis Blood Group
Blood group determined by Le and Se genes coding for fucosyltransferases.
Lewis Antibodies
Lewis Antibodies
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Antibody Screening
Antibody Screening
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P antigen
P antigen
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Autoanti-P antibodies
Autoanti-P antibodies
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M and N Blood Group
M and N Blood Group
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Kell blood group
Kell blood group
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Duffy blood group
Duffy blood group
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Kidd blood group
Kidd blood group
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Autoimmune Hemolytic Anemia (AIHA)
Autoimmune Hemolytic Anemia (AIHA)
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Study Notes
Blood Group Systems
- ABO Blood Group System: A, B, AB, and O are the four major blood types within this system.
- Rh Blood Group System: Determines if a person is Rh positive or Rh negative.
- Other Blood Groups: Includes MNS, I/i, Duffy, Kell, Kidd, P, Lutheran, and Lewis blood group systems.
Common Immunohematology Tests
- Coombs Test (Antiglobulin Test): A test for the presence of antibodies on red blood cells (RBCs).
- RBC Typing: Determines blood type including percentages for O, A, B, and AB types and Rh+ and Rh- frequencies in a specific population (e.g., USA).
- Cross-Matching: A test to ensure compatibility between donor and recipient blood.
- Antibody Screening: Identifies antibodies in the recipient's blood that could react with donor blood.
- Compatibility Testing: A complete examination to assess compatibility between blood donor and recipient to prevent adverse reactions.
Direct Coombs Test
- Detects antibodies bound to RBCs of a patient sample.
- Antibodies attached to patient's red blood cells; Indicates erythroblastosis fetalis or hemolytic anemia.
- Agglutination occurs upon a positive result indicating attached antibodies.
Indirect Coombs Test
- Detects antibodies in the serum that could potentially attack the recipient's red blood cells if transfused.
- Patient's serum + Rh+ RBCs; detects antibodies that might attack fetal red blood cells if the father is Rh+.
- Agglutination indicates antibodies potentially causing hemolytic reactions.
Anti-Rh Antibodies
- Various types of anti-Rh antibodies exist (anti-C, anti-c, anti-E, anti-e, and anti-D).
- Potency ranges from strongest to weakest.
- Incomplete antibodies: Do not bind complement.
- IgG: Active at 37 degrees Celsius.
- Rh is a protein antigen.
- Tested using the indirect Coombs test.
Incomplete Antibodies
- Antibodies that do not directly cause clumping (agglutination) of red blood cells (RBCs).
- Antibodies bind to antigens on RBCs, but do not cause immediate clumping.
Complete Antibodies
- Antibodies that can directly cause clumping (agglutination) of red blood cells (RBCs) due to their ability to cross-link multiple antigens on red blood cells.
H Substance
- The H gene codes for fucosyltransferase, which adds the sugar fucose to a precursor substance (PS).
- This creates the H antigen, a precursor for A, B, and H antigens.
Group A
- The A gene codes for N-acetylgalactosaminyltransferase that adds N-acetylgalactosamine to the H antigen.
Group B
- The B gene codes for galactosyltransferase, which adds galactose to the H antigen.
Bombay Blood Group
- Individuals lack the ability to produce H antigens; thus, cannot produce A or B antigens.
- Phenotypically, they appear as group O.
Lewis Blood Group
- Le gene: codes for L-fucosyltransferase, for attaching fucose to cells; creates Lea antigen.
- Se gene: codes for a-2-L-fucosyltransferase; creates Leb antigen;
- Lele: Co-dominant; Soluble antigens are found in body fluids (plasma).
- IgM antibodies: Can activate complement, leading to hemolysis. Very rarely cause transfusion reactions.
P Antigen
- Three types of P antigens (P, P1, and Pk).
- P' antigen is a binding site for Parvovirus B19.
- Found in secretions like plasma and hydatid fluid.
- IgG antibodies: Can cause Paroxysmal Cold Hemoglobinuria (PCH).
M and N Blood Group
- Rich in sialic acid.
- Two genes code: Glycophorin A and B on chromosome 4 with 5 antigens. These include M, N, S, s, and U
- MN system antibodies: IgM or IgG that do not bind complement and active at room temperature (RT).
Kell Blood Group
- K antigen, second most immunogenic after the D antigen.
- Kell antibodies (e.g., Anti-Kell): IgG type, can bind complement, and are linked to hemolytic disease of the newborn (HDN) and transfusion reactions.
Duffy Blood Group
- Three alleles (Fya, Fyb, and Fy). Four antigens (Fy3, Fy4, Fy5, and Fy6) are present on all normal RBCs.
- Duffy antibodies are IgG and do not bind complement; cause acute or delayed hemolytic transfusion reactions and hemolytic disease of the newborn.
Kidd Blood Group
- Three alleles: Jka, Jkb, and JK3; Kidd antigens transport urea in red blood cells (RBCs).
- Kidd antibodies are IgG, causing hemolytic disease of the newborn (HDN), and delayed hemolytic transfusion reactions.
Transfusion Reactions
- Acute reactions (within 24 hours): Immunologic (e.g., hemolytic, febrile, allergic) or non-immunologic (e.g., circulatory overload, reaction to air).
- Delayed reactions (>24 hours): Immunologic (e.g., hemolytic, graft-versus-host) or non-immunologic (e.g., iron overload).
- Infectious complications are also possible.
Intravascular Hemolysis
- Characteristics include: being evident within minutes, involvement of IgM or IgG antibodies, complement activation, and release of histamine and serotonin.
- Signs may include pain at the infusion site, shock, abnormal bleeding, and release of cytokines.
Autoimmune Hemolytic Anemia (AIHA)
- RBC destruction due to autoantibodies (Aab).
- IgG or IgM antibodies; if complement is fixed, causes intravascular hemolysis; otherwise, extravascular hemolysis.
- Antibody-coated RBCs lose membrane in the spleen & form spherocytes.
- Warm AIHA (80%): IgG antibodies bind at 37°C, mostly targeting Rh antigens.
- Cold AIHA (20%): IgM antibodies bind at 4°C and fix complement, affecting blood antigens.
Warm Autoimmune Hemolysis
- Common in middle-aged and older females.
- 50% unknown cause; others are due to lymphoid neoplasms, solid tumors, connective tissue diseases, or drugs.
Cold Autoimmune Hemolysis
- Chronic AIHA: Commonly affects the elderly and is associated with B-cell lymphoma, with antibodies against i antigens.
- Acute AIHA is associated with infections such as Mycoplasma pneumoniae, IMN, or PCH; antibodies are typically polyclonal and directed toward P antigens. May affect children due to congenital syphilis.
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Description
Test your knowledge on blood group systems, immunohematology tests, and their significance. This quiz covers the ABO and Rh blood group systems, common tests such as the Coombs Test, RBC Typing, and compatibility testing. Understand the importance of ensuring blood compatibility in transfusions.
