Immunologic Principles Related to Blood Bank Flashcards
What is the ultimate role of immunohematology?
Successfully provide safe and effective blood components for treatment
Intravascular hemolysis occurs when?
Cell membrane is destroyed by complement (not by antibody)
Which causes immediate problems?
-Intravascular hemolysis
-Extravascular hemolysis
Intravascular hemolysis
In immunohematology, what is the most common and most severe cause of intravascular hemolysis?
Wrong ABO type of blood given to a patient
Extravascular hemolysis
Antibody is attached to red cell membrane
What removes antibody coated red cells from circulation during extravascular hemolysis?
The spleen
Examples of extravascular hemolysis (2)
-Delayed transfusion reactions
-Hemolytic Disease of the Newborn
Which immune response does blood bank focus on:
-Humoral
-Cellular
Humoral
Definition: Substance capable of inducing a specific immune response
Antigen
Another name for antigen
Immunogen
Portion of the antigen where the antibody combines
Epitope
Another name for epitope
Antigenic determinant
How can antigens be acquired? (3)
-Injection
-Inhalation
-Ingestion
Definition:
Overall strength of reaction between several epitopes and antibodies
Avidity
Avidity is dependent on what 3 factors?
-Affinity of the antibody
-Valency
-Noncovalent attractive forces
Protein synthesized by plasma cells
Antibody
Another name for antibody
Immunoglobulin
Antibody to a foreign substance
Alloantibody
Antibody to self
Autoantibody
What are classes of antibodies based on?
Heavy chain composition
What are the heavy chains of concern in blood bank?
IgM (Mu) and IgG (Gamma)
What are the light chains found in immunoglobulins?
Kappa and Lambda
Immunoglobulin structure:
This portion binds to the antigenic determinant (epitope)
Fragment antigen binding portion (Fab)
Immunoglobulin structure:
This includes the binding site for complement and macrophage Fc receptors
Fragment crystallizable portion (Fc)
Immunoglobulin structure:
Disulfide bonding which holds the light chain and heavy chain together
Hinge region
Immunoglobulin structure:
Allows flexibility for immunoglobulin to attach to antigen
Hinge region
What 2 enzymes can split the antibody molecule at the hinge region?
Papain and Pepsin
Number of binding sites for IgG
2
Number of binding sites for IgM
10
IgM has how many monomers?
5
IgG has how many monomers?
1
IgG or IgM:
Crosses the placenta
IgG
IgG or IgM:
Reacts at room temperature
IgM
IgG or IgM:
Reacts at 37C
IgG
IgG or IgM:
First antibody seen in primary immune response
IgM
IgG or IgM:
Is part of the anamnestic immune response
IgG
IgG or IgM:
Naturally occurring
IgM
IgG or IgM:
Must be previously exposed in order to create
IgG
IgG or IgM:
Requires enhancer to visualize lattice formation
IgG
Where antibodies are located
Plasma or serum
Where antigens are located
On the red blood cell membrane
Strength of the binding between a single antibody and an epitope of an antigen
Affinity
First stage of antigen-antibody reactions
Sensitization stage aka Recognition stage
Second stage of antigen-antibody reactions
Agglutination stage
Antigen-antibody stage in which the antibody is attached to antigen on the red cell membrane but a visible reaction is NOT observed
Sensitization Stage
Antigen-antibody reactions:
Random pairing determined largely by chance
Sensitization stage
What is the serum-to-cell ratio? (#s)
2 drops of plasma/serum to 1 drop of red cells
TRUE or FALSE: Increasing the serum/plasma amount increases the concentration of antibodies available to bind to red cell antigens but does NOT increase reaction probability
TRUE
What environmental factors influence the sensitization stage of antigen-antibody reactions? (4)
-Incubation time (15-60 minutes)
-Temperature (IgG 37C/IgM RT or lower)
-pH (optimal ~7.0)
-Ionic strength (physiologic saline)
___________ forms when red cells are in close proximity to promote lattice formation between the antibody and antigenic sites on adjacent red cells
Agglutination
What factors influence agglutination? (3)
-Distance between red blood cells (zeta potential)
-Optimal concentrations of antigen and antibody (zone of equivalence)
-Effect of centrifugation
Definition:
The force or repulsion between red cells in a physiologic saline solution
Zeta potential
Red cells possess a net _______ charge on the cell surface in a saline suspension. ________ from the saline environment are attracted to these charges.
-negative
-cations (+ charge)
What is IgM able to facilitate agglutination better than IgG?
It is larger in size with more binding sites
Excess antibody
Prozone
Excess antigen
Postzone
Maximum agglutination is observed when amount of antibodies = amount of antigens
Zone of equivalence
Prozone and postzone can both cause what type of test results?
False negatives
What helps facilitate the formation of a lattice network by forcing red cells closer together?
Centrifugation
Why is hemolysis considered a positive reaction in blood bank?
Hemolysis can mean that complement was activated by the antibody (probable IgM)
Primary response vs Secondary/anamnestic response:
Takes 5-7 days
Primary
Primary response vs Secondary/anamnestic response:
Takes 24-48 hours
Secondary
Primary response vs Secondary/anamnestic response:
Total titer is higher
Secondary
Primary response vs Secondary/anamnestic response:
Titer lasts longer
Secondary
Primary response vs Secondary/anamnestic response:
More IgM
Primary
Primary response vs Secondary/anamnestic response:
Mostly IgG
Secondary
Primary response vs Secondary/anamnestic response:
Memory B cells
Secondary
Primary response vs Secondary/anamnestic response:
Needs more antigen to stimulate
Primary
Primary response vs Secondary/anamnestic response:
Delayed hemolytic transfusion reaction
Secondary
White cells that synthesize antibodies
Plasma cells
Zeta potential can be easily overcome by this immunoglobulin to produce agglutination
IgM