Immunology and Genetics for Blood Bank Flashcards
Objective
IgG properties that promote serological reactivity of agglutination or hemolysis
- Monomer
- Reacts at 37°C body temp
- Secondary response
- Small size means it can escape venous space to cause extravascular hemolysis
- Only IgG3 activates complement
Objective
IgM properties that promote serological reactivity of agglutination or hemolysis
- Pentamer
- Reacts at 20°C room temp provides easy testing
- Primary response
- Activates complement
- Large size means it stays stuck inside venous space
Objective
Which protein in the complement system is ID’d on the RBC after complement activation?
C3b
It attaches to the RBC antigen before destruction
Objective
Compare and contrast properties of the RBC component that make them an ideal product for transfusion
- Designed to carry oxygen efficiently
- Non-toxic to human body
- Naturally sourced
Objective
Compare and contrast properties of the RBC component that make them an less than ideal product for transfusion
- Transplant rejection due to immune stimulation
- Infectious
- Limited shelf life
- Volunteer collection only
Objective
Use the Punnett square to predict phenotypic expression of given genes in offspring
:)
Objective
Which RBC chemical properties are increased during storage and why?
- Lactic acid bc metabolic byproduct
- Plasma K and Hgb due to hemolysis
Objective
Which RBC chemical properties are decreased during storage?
- % viable cells bc hemolysis
- Glucose bc used for glycolysis
- ATP bc cells use them up
- pH bc more acidic lactate made
- 2,3 DPG bc it degrades over time
Objective
How do anticoagulant preservatives mitigate storage changes?
- Citrate chelates calcium to prevent clotting
- Monobasic Sodium Phosphate maintains pH and 2,3 DPG levels
- Dextrose is an ATP substrate
- Adenine makes ATP
Objective
cis and trans in genetics
- cis: two genes inherited together on the same chromosomes (e.g, AB blood antigens)
- trans: two genes inherited together from opposite chromosomes
Word of the day
Haplotype
- 2 genes inherited together on the same chromosome but code for different Ag
- Genes are linked
- Do not follow Hardy-Weinberg equilibrium equation (don’t add up to 1)
Is the complement system innate or acquired immunity?
Innate immunity
What does adding plasma do to blood specimen?
Hemolysis
What causes agglutination?
IgM latticing (Ag-Ab)
Does compatible blood agglutinate? Why or why not?
No agglutination because the Ab does not have the right Ag to bind, which is good for blood tranfusions
Does incompatible blood agglutinate? Why or why not?
Yes, agglutination happens because
Ab have Ag to bind, which is bad for blood transfusions
Stable Ab-Ag reactions depend on what?
- fit (size/shape)
- charge
- avidity
Outside forces that can be controlled
- time
- temp
- pH
- ionic strength
- centrifugation
How is blood bank like algebra?
- Figure out which Ag is on pt RBCs
- Figure out which antibody is coming from pt plasma
Why do we transfuse blood?
- When the demand for oxygen exceeds 50% of the oxygen you already have, the compensatory mechanisms fail, and the patient requires transfusion
- To maintain hemostasis (such as coagulation cascade vs clot formation)
How does the body compensate for anemia?
Increase plasma volume, heart rate, respiratory rate, and RBC oxygen extraction
Explain oxygen binding and unloading in context of 2,3-DPG
- During oxygen unloading, 2,3-DPG takes O2’s place and creates a tight binding structure. More O2 released to tissues
- During oxygen binding, 2,3-DPG leaves to create a relaxed binding structure. Less O2 delivered to tissues
Explain why 2,3-DPG levels decrease over time in blood product
- It degrades over time, leading to O2 too tightly bound to Hgb -> hypoxia potential
- Can’t pick up or release O2
Left shift in oxygen-dissociation curve
Less oxygen delivered to tissues
Increased pH and abnormal Hgb
Decreased temp, P50, 2,3-DPG
Right shift oxygen-dissociation curve
More oxygen delivered to tissues
Increased temp, P50, 2,3-DPG
Decreased pH
Criteria for viable blood product
- RBC survival >75% post transfusion
- Free Hgb (hemolyzed RBC) < 1%
Criteria for non-viable blood product
- Increased cardiac output (transfusion tends to decrease it)
- Decreased pO2 tension (can’t carry O2)
What percent of RBCs are cleared from daily circulation?
1%
Why does ATP loss reduce deformability and permeability of RBC?
- Deformability impacted because no ATP available to phosphorylate spectrin
- Permeability is reduced because calcium and sodium ions accumulate inside the RBCS, potassium and water are lost, which leads to a rigid and dehydrated cell that gets sequestered by spleen
Phenotype
- Physical gene expression
- Detected by serologic testing
- Antigen
Genotype
- Actual inherited genes
- Detected by molecular testing
- Allele (individual expression of Ag)
Locus
Location on chromosome where gene can be found
Allele
Variety within gene
Ag produced by allele
Dosage
When Ag expression is less because of heterozygous allele inheritance and more expressed due to homozygous allele inheritance
How is gene frequency calculated?
Hardy-Weinberg
p^2 + 2pq + q^2 = 1 (independent inheritance of p and q if equal 1)
Hardy-Weinberg assumptions
- Genotypes distributed in proportion to frequency in population
- Genotypes remain constant across generations
