Immunohematology, also known as Blood Banking, is a vital discipline within clinical laboratory science that focuses on the study of blood group antigens and antibodies. It plays a crucial role in ensuring safe blood transfusions, preventing transfusion reactions, and understanding the immune interactions between donor and recipient blood.
This section introduces the foundational concepts that every Medical Laboratory Scientist, Technician, and Blood Bank professional must master before advancing to specific blood group systems.
Topics Covered in This Chapter
- Basic principles of Immunohematology and Blood Banking
- Antigen–Antibody interactions and their clinical relevance
- Structure and function of immunoglobulins (IgG, IgM)
- Complement system and its role in immune hemolysis
- Hemagglutination and agglutination reactions
- Overview of blood group genetics and inheritance patterns
- Laboratory safety and quality control in blood banking procedures
Why It Matters
Understanding the immune basis of transfusion medicine helps prevent life-threatening complications, supports accurate blood typing and crossmatching, and ensures the reliability of patient results in clinical practice.
This article serves as a foundation for upcoming topics, such as ABO and Rh systems, antibody identification, and transfusion reactions.
Learning Outcomes
After studying this section, learners should be able to:
- Apply safety principles in handling and testing blood specimens.
- Define the major components of the immune system relevant to blood banking.
- Explain the mechanisms of antigen–antibody reactions.
- Recognize the importance of immunoglobulin classes in transfusion testing.
60 MCQs (4301 – 4360):
- What is the main purpose of Immunohematology in laboratory science?
a) To study white blood cell morphology
b) To identify infectious diseases
c) To ensure safe and compatible blood transfusions
d) To measure blood glucose levels - Which of the following best describes an antigen?
a) A molecule that binds oxygen
b) A substance capable of stimulating an immune response
c) A protein that digests antibodies
d) A lipid component of red cell membranes - The specific immune response depends on which key element?
a) Macrophage size
b) Antigen–antibody reaction
c) Platelet activation
d) Electrolyte concentration - Which class of immunoglobulin is most effective at agglutinating red cells at room temperature?
a) IgG
b) IgA
c) IgM
d) IgE - Which antibody class can cross the placenta and cause hemolytic disease of the newborn?
a) IgA
b) IgM
c) IgE
d) IgG - The complement system primarily assists antibodies in:
a) Stimulating antigen production
b) Causing cell lysis and promoting inflammation
c) Producing new antibodies
d) Enhancing white cell formation - Agglutination involves:
a) Destruction of red cell membranes
b) Binding of antigen and antibody causing visible clumping
c) Separation of serum proteins
d) Denaturation of plasma enzymes - Which test phase enhances the detection of IgM antibodies?
a) 37°C incubation phase
b) Immediate-spin phase
c) Antiglobulin phase
d) Enzyme phase - The indirect antiglobulin test (IAT) detects:
a) Antigens on donor cells
b) Antibodies present in patient serum
c) Complement proteins
d) Clotting factors - Which immunoglobulin reacts optimally at body temperature (37°C)?
a) IgM
b) IgG
c) IgA
d) IgE - In Immunohematology, the term “sensitization” refers to:
a) Visible red cell agglutination
b) Binding of antibody to antigen without visible agglutination
c) Cell lysis by complement activation
d) Denaturation of antibodies - The antiglobulin reagent is designed to detect:
a) Free serum proteins
b) Antibody-coated red blood cells
c) Plasma enzymes
d) Hemoglobin variants - What is the role of enhancement media such as LISS and PEG?
a) Increase antibody production
b) Accelerate antigen–antibody binding
c) Reduce hemolysis
d) Dilute serum proteins - Which immune response occurs first upon initial exposure to an antigen?
a) Secondary immune response
b) Delayed hypersensitivity reaction
c) Primary immune response
d) Memory response - Which of the following is NOT a cellular component of the immune system?
a) Lymphocytes
b) Monocytes
c) Basophils
d) Platelets - Complement activation can lead to:
a) Hemolysis of red cells
b) Decreased antibody production
c) Loss of plasma volume
d) Increase in hemoglobin synthesis - What is the basic structural unit of an immunoglobulin molecule?
a) One heavy and two light chains
b) Two heavy and two light chains
c) One heavy and one light chain
d) Four heavy chains only - Which of the following best defines an alloantibody?
a) Antibody produced against self-antigens
b) Antibody formed after exposure to foreign antigens of the same species
c) Antibody produced by the complement pathway
d) Antibody formed without antigen exposure - Which laboratory safety measure is most critical in blood banking?
a) Wearing sterile gloves during testing
b) Using only glass pipettes
c) Avoiding refrigeration of samples
d) Mixing patient and donor samples directly - The direct antiglobulin test (DAT) is used to detect:
a) Free serum antibodies
b) Antibodies or complement bound to red cells in vivo
c) Hemoglobin concentration
d) Plasma proteins - The immune system’s memory response is characterized by:
a) Lower antibody levels
b) Slower antibody production
c) Faster and stronger antibody response
d) Absence of antigen recognition - Which immunoglobulin has a pentamer structure?
a) IgA
b) IgG
c) IgM
d) IgE - Which factor can affect antigen–antibody reactions?
a) pH, temperature, and ionic strength
b) Blood pressure and glucose level
c) Platelet count
d) Hemoglobin type - The zone of equivalence in antigen–antibody reactions refers to:
a) Excess antigen present
b) Equal antigen and antibody concentration
c) Excess antibody present
d) Absence of antigen - The strength of antigen–antibody binding is called:
a) Avidity
b) Specificity
c) Titer
d) Affinity - Hemagglutination is used in blood banking to:
a) Detect viruses
b) Identify red cell antigens and antibodies
c) Determine plasma glucose
d) Analyze clotting factors - The immune response that develops without prior exposure to an antigen is called:
a) Acquired immunity
b) Adaptive immunity
c) Innate immunity
d) Delayed response - Which of the following reagents enhances antibody uptake by reducing zeta potential?
a) LISS
b) Saline
c) Albumin
d) Enzyme solution - An antigen that is found on the red cell membrane is referred to as a:
a) Plasma antigen
b) Red cell antigen
c) Serum antigen
d) Complement antigen - The antiglobulin test (Coombs test) is primarily used to:
a) Measure serum protein levels
b) Detect antibody-coated red cells
c) Assess leukocyte function
d) Evaluate coagulation status - What is the minimum hemoglobin concentration required for a male blood donor?
a) 12.0 g/dL
b) 12.5 g/dL
c) 13.0 g/dL
d) 13.5 g/dL - Which of the following is a cause for indefinite deferral from blood donation?
a) Reactive test for Babesia species
b) Residence in an endemic malaria region for 5 years
c) Positive test for Trypanosoma cruzi
d) History of chicken pox vaccination - Prior to blood donation, the intended venipuncture site must be cleaned with a scrub solution containing:
a) Hypochlorite
b) Green soap
c) 10% acetone
d) Povidone iodine - Which of the following infectious agents relies solely on donor questioning to avoid transmission via transfusion?
a) Trypanosoma cruzi
b) Plasmodium falciparum
c) HCV
d) CMV - According to AABB Standards, what is the minimum hemoglobin level for an autologous donor?
a) 11.0 g/dL
b) 12.0 g/dL
c) 12.5 g/dL
d) 13.0 g/dL - All donor blood testing must include which of the following?
a) Complete Rh phenotyping
b) Anti-CMV testing
c) Direct antiglobulin test
d) Serological test for syphilis - What is the primary reason that infectious agents can be transmitted following blood transfusion?
a) Pathogen reduction technology failure
b) Donor in the window period of early infection
c) Leukocyte-reduction failure
d) Donor history questionnaire not completed - The transport temperature for Apheresis Platelets is:
a) 1-6°C
b) 1-10°C
c) 18-20°C
d) 20-24°C - What is the correct storage temperature for Fresh Frozen Plasma (FFP)?
a) 4°C
b) –20°C
c) –40°C
d) 37°C - During storage, the concentration of 2,3-diphosphoglycerate (2,3-DPG) decreases in a unit of:
a) Platelets
b) Fresh Frozen Plasma
c) Red Blood Cells
d) Cryoprecipitated AHF - Most blood group system genes and their resulting genetic traits display what type of inheritance?
a) Sex-linked dominant
b) Sex-linked recessive
c) Autosomal recessive
d) Autosomal codominant - The linked HLA genes on each chromosome constitute a(n):
a) Allele
b) Trait
c) Phenotype
d) Haplotype - Which of the following antibodies is usually clinically insignificant?
a) Anti-P
b) Anti-P1
c) Anti-Pk
d) Anti-p - A blood donor has the genotype: hh, AB. Using anti-A and anti-B antisera, the donor’s red cells will type as group:
a) A
b) B
c) O
d) AB - Which of the following is responsible for the production of blood group antibodies?
a) B cells
b) T cells
c) NK cells
d) Dendritic cells - In a primary immune response, which immunoglobulin class appears first?
a) IgG
b) IgM
c) IgA
d) IgE - Which immunoglobulin class can cross the placenta?
a) IgG
b) IgM
c) IgA
d) IgE - Which of the following immunoglobulins is most efficient at causing direct hemagglutination?
a) IgG
b) IgM
c) IgA
d) IgE - Appropriate antigen-antibody ratios are important to avoid an excess of unbound antibody, which is known as:
a) Dosage effect
b) pH effect
c) Postzone effect
d) Prozone effect - Many enhancement media used in the blood bank promote hemagglutination by reducing which of the following?
a) Hydrophilic forces
b) Low ionic potential
c) Van der Waals forces
d) Zeta potential - The addition of antibody-sensitized red cells (Check Cells) to all negative anti-human globulin (AHG) tests ensures that:
a) The test was interpreted correctly
b) The test was incubated at the correct temperature
c) AHG reagent was added to each test
d) Patient serum was added to each test - In which of the following is the indirect antiglobulin test utilized?
a) Reverse ABO testing
b) Immediate spin crossmatch
c) C antigen testing
d) Antibody detection (screening) test - Polyspecific AHG reagents contain:
a) Anti-IgG
b) Anti-C3d
c) Anti-IgG and anti-IgM
d) Anti-IgG and anti-C3d - A negative result using solid phase adherence assays will demonstrate indicator red cells as:
a) A red blood cell pellet in the bottom of the well
b) A diffuse pattern of red blood cells throughout the well
c) Red blood cell clumps symmetrically located throughout the well
d) A red supernatant, indicating lysis - The membrane attack complex (MAC) formed during complement activation consists of:
a) C1q, C1r, C1s
b) C3a, C3b, C3d
c) C5a, C5b
d) C5b through C9 - In ABO hemolytic transfusion reactions, complement is activated via which pathway?
a) Alternative
b) Classical
c) Lectin
d) Polyclonal - Key cytokines involved in the differentiation and proliferation of erythrocytes include:
a) Erythropoietin (EPO) and granulocyte macrophage-colony stimulating factor (GM-CSF)
b) Interleukin 3 (IL-3) and flt3 ligand (FL)
c) Granulocyte macrophage-colony stimulating factor (GM-CSF) and flt3 ligand (FL)
d) Erythropoietin (EPO) and interleukin 3 (IL-3) - 2,3-DPG’s role in RBC metabolism is to:
a) Protect RBCs from hexose monophosphate shunt degradation
b) Generate cell energy anaerobically in the form of ATP
c) Maintain hemoglobin Fe²⁺ to bind O₂
d) Increase the release of O₂ from oxyhemoglobin to the tissues - Transfusion of which of the following is needed to help correct hypofibrinogenemia due to DIC?
a) Whole Blood
b) Fresh Frozen Plasma
c) Cryoprecipitated AHF
d) Platelets - Which of the following is used to treat hemophilia B?
a) Factor IX concentrate
b) Factor VIII concentrate
c) Cryoprecipitated AHF
d) DDAVP
📌 How to Use This Practice Set
- Answer each question before checking the key.
- Focus on why the correct answer is right and the others are wrong.
- Use this set as timed practice to simulate the real exam environment.
Answer Key
Answer Key:
- c) To ensure safe and compatible blood transfusions
- b) A substance capable of stimulating an immune response
- b) Antigen–antibody reaction
- c) IgM
- d) IgG
- b) Causing cell lysis and promoting inflammation
- b) Binding of antigen and antibody causing visible clumping
- d) Enzyme phase
- b) Antibodies present in patient serum
- b) IgG
- b) Binding of antibody to antigen without visible agglutination
- b) Antibody-coated red blood cells
- b) Accelerate antigen–antibody binding
- c) Primary immune response
- d) Platelets
- a) Hemolysis of red cells
- b) Two heavy and two light chains
- b) Antibody formed after exposure to foreign antigens of the same species
- a) Wearing sterile gloves during testing
- b) Antibodies or complement bound to red cells in vivo
- c) Faster and stronger antibody response
- c) IgM
- a) pH, temperature, and ionic strength
- b) Equal antigen and antibody concentration
- d) Affinity
- b) Identify red cell antigens and antibodies
- c) Innate immunity
- a) LISS
- b) Red cell antigen
- b) Detect antibody-coated red cells
- c) 13.0 g/dL
- c) Positive test for Trypanosoma cruzi
- d) Povidone iodine
- b) Plasmodium falciparum
- b) 12.0 g/dL
- d) Serological test for syphilis
- b) Donor in the window period of early infection
- d) 20-24°C
- b) –20°C
- c) Red Blood Cells
- d) Autosomal codominant
- d) Haplotype
- b) Anti-P1
- c) O
- a) B cells
- b) IgM
- a) IgG
- b) IgM
- d) Prozone effect
- d) Zeta potential
- c) AHG reagent was added to each test
- d) Antibody detection (screening) test
- d) Anti-IgG and anti-C3d
- a) A red blood cell pellet in the bottom of the well
- d) C5b through C9
- b) Classical
- d) Erythropoietin (EPO) and interleukin 3 (IL-3)
- d) Increase the release of O₂ from oxyhemoglobin to the tissues
- c) Cryoprecipitated AHF
- a) Factor IX concentrate
Top 8 Medical Laboratory Scientist (MLS) Exams:
Top 8 Medical Laboratory Scientist (MLS) Exams that are recognized globally and can help professionals validate their credentials and enhance their career opportunities:
1. ASCP – American Society for Clinical Pathology (USA)
- Exam Name: MLS(ASCP)
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- Exam Name: MLT(AMT) or MT(AMT)
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