From lectures

Question 1

Define antigen

Answer 1

A cell-surface protein capable of stimulating antibody production in an individual lacking that cell-surface protein

Question 2

Define immunogen

Answer 2

the specific part, or parts, of an antigen that invoke the formation of antibody​

Question 3

define antibody

Answer 3

Immunoglobulin produced in response to the introduction of a foreign antigen stimulated by the immunogenic part of the antigen. The antibody produced may result in removal of that antigen​

Question 4

Why do IgM antibodies cause diresct agglutination while IgG require potentiators or AHG for agglutination.

Answer 4

IgM antibodies are large

Question 5

difference between a direct and indirect test—-

Question 6

what is an indirect antiglobulin test (IAT)? what is commonly used as a reagent and how?

Answer 6

testing antigen-antibody aggluttination to identify patient antibodies
mix patient sample with donor RBCs
incubated for binding
washing

Question 7

describe fully an IAT

Answer 7

Primary - Incubation step
Secondary - Agglutination step

Question 8

Explain the difference between an antigen and an immunogen

Answer 8

An antigen is any substance capable of inducing an immune response and can include non-immunogenic substances.

Immunogen specifically refers to the part of an antigen that can trigger the production of antibodies

Question 9

What are antithetical antigens, and provide examples?

Answer 9

Antithetical antigens = antigens that are the result of alternative alleles at the same locus (different versions of the same antigen, determined by genetic variation).
Examples = M and N, S and s, and Fya and Fyb.

Question 10

Describe the types of antibodies commonly found in blood groups and their characteristics.

Answer 10

Blood group antibodies are usually IgM or IgG, although some may be IgA.
IgM - naturally occurring,
IgG - immune.

Question 11

what is the difference between IgM and IgG in terms of agglutination ability

Answer 11

IgM antibodies = directly agglutinate antigen-positive red cells in saline

IgG antibodies = most require potentiators or AHG to effect agglutination.

Question 12

Why are ABO antibodies termed “naturally acquired”?

Answer 12

produced without requiring stimulation by foreign red cells
Most adults have antibodies to the A and/or B antigens naturally occurring to those ABO antigens they lack.

Question 13

Discuss the factors influencing immunogenicity.

Answer 13

recognition of the substance as foreign

the molecular weight (typically at least 10,000 Daltons),

the composition of the substance (protein, carbohydrate, or lipid-based),

the amount and frequency of its introduction

Question 14

define immunogenicity

Answer 14

ability to provoke an immune response

Question 15

Explain why some IgG antibodies require potentiators or AHG for agglutination.

Answer 15

IgG is too small

AHG contains an antibody to IgG and so recognises and binds to the Fc portion of any IgG antibody.

Adding AHG allows cross-linking of red cells and therefore agglutination.

Question 16

What factors contribute to the production of immune antibodies?

Answer 16

immunogenicity of the antigen concerned,

the amount and frequency of the stimulation involved,

the recipient’s immune response capability.

Question 17

Why does red cell antibody production not routinely occur after transfusion or pregnancy????????????

Question 18

What factors contribute to the production of immune antibodies?

Answer 18

Immunogenicity of the antigen: Some antigens are more likely to stimulate an immune response than others.

Amount and frequency of antigen exposure: Sufficient exposure to the antigen over time is required to trigger an immune response.

Recipient’s immune response capability: The recipient’s overall immune health and genetic factors influence their ability to generate antibodies.

Immunomodulatory factors: Certain medications, medical conditions, or immune-suppressing treatments may affect the immune response

Question 19

Discuss the clinical significance of blood group antibodies.

Answer 19

medicine and prenatal care:
etermine compatibility between donor and recipient blood or tissues, preventing adverse reactions such as hemolytic transfusion reactions or hemolytic disease of the fetus and newborn (HDFN).

Blood group antibodies can cause agglutination or hemolysis of incompatible red blood cells, leading to serious health complications or even death if not properly managed.

Question 20

What are the different ways blood group antigens can be introduced into circulation, and how do they lead to antibody formation?

Answer 20

transfusion of mismatched blood,

fetal-maternal blood exchange during pregnancy,

or transplantation of tissues containing foreign antigens.

When the recipient’s immune system encounters these foreign antigens, it may produce antibodies against them through the process of sensitisation, leading to antibody formation.

Question 21

What percentage of transfused patients, pregnant women, and transplant patients are likely to produce red cell antibodies?????????????????

Answer 21

Transfused patients: Approximately 2-9% may produce antibodies after transfusion, depending on various factors.
Pregnant women: About 1% may develop antibodies due to fetal-maternal blood exchange.
Transplant patients: Less than 2% may produce antibodies after transplantation.

Question 22

Explain the primary and secondary stages of agglutination in antigen-antibody reactions.

Answer 22

Primary stage: Occurs when antibody meets its corresponding antigen, leading to reversible binding via weak forces. This stage is also known as sensitisation.

Secondary stage: Involves cross-linking of red cells by antibody molecules, leading to visible agglutination. It depends on red cell dilution and attraction/repulsion forces.

Question 23

How does AHG facilitate the agglutination of red cells coated with IgG antibodies?

Answer 23

AHG contains antibodies to IgG and recognizes and binds the Fc portion of IgG antibodies. This binding allows for cross-linking of red cells coated with IgG antibodies, facilitating agglutination.

Question 24

Describe the blood group nomenclature system outlined in the lecture.

Answer 24

The blood group nomenclature system represents antigens, phenotypes, genes, and Rh haplotypes using various symbols and conventions, including capital letters, superscript/subscript letters and numbers, and positive/negative symbols enclosed in brackets.

Question 25

How are antigens represented in blood group nomenclature?

Answer 25

using capital letters, superscript letters, subscript numbers, non-subscript numbers, or a combination of these symbols. For example, A, B, K, Fya, Fyb, etc.

Question 26

Explain how phenotypes indicating RBC antigen presence are represented.

Answer 26

Phenotypes indicating RBC antigen presence are represented using positive and negative symbols enclosed in brackets. For example, Fy(a+b-), K-k+, Kp(a-b+), etc.

Question 27

How are genes causing the production of an antigen denoted in blood group nomenclature?

Answer 27

Genes causing the production of an antigen are denoted in text by the use of italics and superscript numbers or letters. For example, B, K, Fya, K11, etc.

Question 28

Discuss the shorthand used for Rh haplotypes in blood group nomenclature.

Answer 28

Rh haplotypes are represented using superscript symbols and letters or subscript numbers or letters. For example, r/, r//, ry, R1, R2, Ro, Rz, etc.

Question 29

why may anti-Jk^a react more strongly to Jk(a+b-)(homozygous for Jka) than Jk(a+b+)(heterozygous)?
and how does this show the dosage effect?

Answer 29

more Jka antigens on surface = more antibody binding to cell = stronger reaction
dosage effect shown as the absence of the competing antigen (Jk^b) allows for a higher expression (dosage) of Jk^a antigens and a stronger antibody-antigen interaction.

Question 30

what does IAT (indirect antiglobulin technique) detect?

Answer 30

IgG antibodies at 37*C
complement fixing antibodies
Rh antibodies

Question 31

which antibodies in the panel are clinnically insignificant and can be ruled out?

Answer 31

Cw, Kpa, P1, Lua, Lea, Leb

Question 32

what are the three methods of performing antibody identification?

Answer 32

traditional tube technique
gel column agglutination technology
solid phase technology

Question 33

why is column agglutination tech so commonly used?

Answer 33

lower sample volume required
reproducible results due to standardisation
stable reaction endpoints
eliminates washing steps
control cell not often required

Question 34

what is haemolytic disease of the foetus/newborn (HDFN) (erythroblastosis fetalis)?
what causes it?

Answer 34

destruction of red blood cells (hemolysis) in a fetus or newborn due to an incompatibility between the blood types of the mother and baby
—anemia, jaundice, and in severe cases, fetal hydrops (accumulation of fluid in fetal tissues)

Question 35

what is the purpose of the enzyme treatment panel in antibody identification?

Answer 35

altering the antigenic properties of RBCs through enzymatic digestion.

Question 36

what enzymes are used in the enzyme treatment panel?

Answer 36

papain, ficin, or bromelain