Lecture 2: Serology Flashcards
Judge serologic reactivity by a standard 0-4+ grading scheme:
A reaction with no agglutination. Cells appear to remove from cell button as a smoke or cloud.
0 (Negative)
Judge serologic reactivity by a standard 0-4+ grading scheme:
A reaction with solid agglutination. A cell button is shaken, all cells stick together in one solid chunk floating in a liquid background.
4+
Judge serologic reactivity by a standard 0-4+ grading scheme:
A reaction with very small agglutinates. A cell button is shaken, agglutinates appear to come off as cookie bites from the button.
1+
Judge serologic reactivity by a standard 0-4+ grading scheme:
A reaction with many small agglutinates in a clear background. As cell button is shaken, agglutinates appear to crumble off into solution.
2+
Judge serologic reactivity by a standard 0-4+ grading scheme:
A reaction with many large agglutinates in a clear background. As cell button is shaken, agglutinates remove easily in large chunks.
3+
Define Monoclonal
Antibody derived from a single ancestral antibody-producing parent cell
Antigen
A substance recognized by the body as being foreign, which can cause an immune response.
In blood banking, antigens are usually, but not exclusively, found on the red blood cell membrane.
Antibodies
A protein substance secreted by plasma cells that is developed in response to, and interacting specifically with, an antigen.
In blood banking, it is found in serum, from either a commercial manufacturer or a patient.
True or False: Using a population frequency chart, we can find the antigen listing. The % on the chart is the frequency of presence in the population called “incidence”
True
What is the purpose of Phenotype testing?
to identify unknown antigens on a red cell, use known anti-sera
True or False: A person makes an antibody for an antigen they do not have on their red cells.
True.
the antithetical antigen does not matter.
True or False: Compatible blood for an antibody is 100% population frequency of the antigen.
True.
You will phenotype donor blood for the antigen and loo for a negative reaction
What is antibody ID?
Known cells will be used to identify an unknown antibody
True or False: All test results need to be recorded at the end of the day.
False.
All test results need to be recorded as they are tested. There are strict guidelines for how long documents need to be kept. Consult your procedures before discard.
What is the number 1 cause of transfusion reaction ?
data entry error
True or False: All data entry needs to have a second tech review.
True.
If you are entering results from a worksheet into a computer, a second tech must check your work
True or False: All original documents need to be legible and permanent.
True.
It is forbidden to use white out, pencil, or scratching out, instead single line crosscut errors followed by date and initials.
True or False: Hemolysis can indicate a positive reaction in blood bank testing.
True
True or False: Patient records shall be compared to current results and any discrepancies shall be investigated and appropriate action taken before a unit is dissed for transfusion.
True
What is the 3-Day Rule?
A sample shall be obtained from the patient within three days of the scheduled transfusion.
Samples shall be retained for at least 7 days post transfusion.
There shall be _____ determinations of the recipients ABO blood group and Rh type.
two
For each reagent, one ______ and one _____ control needs to be run each day of use.
positive, negative.
All QC errors must be resolved before patient testing can commence.
Can kit contents be mixed?
No, Kit contents may NOT be mixed.
QC the QC material once per shipment via parallel test. Manager must monitor QC at least monthly.
Critical Equipment: Temperatures of critical equipment need to be monitored at least _____
daily
Equipment must be maintained according to manufacturer’s guidelines.
-Centifuge calibration at least _______.
bi-annually
A program of quality control shall be established that is sufficiently comprehensive to ensure that reagents, equipment and methods preform as _____
expected
When do I perform QC?
Daily:
-run before pt testing
-tests reagents before use
-Maunual reagents are run on a daily basis in their typical method: IS or AHG
Non-routine:
-run with patient testing
-tests test system
-reagents are used for a specific test
-may have to consult package insert for instructions
What color is Antibody reagent A?
blue
What color is Antibody reagent B?
Yellow
What color is Antibody reagent D
No color, just clear
What color is Antibody reagent G?
may or may not be green
What is special about red cells (antigens)?
They are screen and panel cells that are from one human donor that is type O.
Reverse cells may be multiple human donors
Ex: 3% picture of tube testing and 0.8% mixture for gel testing.
Outdates 3-5 weeks.
Define Poly-clonal
antibody for a specific antigen is made from multiple plasma cell sources to detect multiple sites on the same antigen
Define Mono-clonal
antibody for a specific antigen is made from a single plasma cell source to detect a single site on the antigen
Define Poly-Specific
antibody mixture that detects multiple antigens or detects the antigen in different ways (IgG and IgM) to give one result.
Define Mono-Specific
single antibody mixture to pick up a single antigen
How are polyclonal antibodies made?
- Usually rabbit sourced
- Immunize rabbit against desired antigen
- Purify immunized rabbit serum for desired antibody
Advantages:
-More likely to react with antigen because it detects more sites of the antigen
Disadvantages:
-Can pick up non-specific reactivity, non-standardized, difficult to determine potency of a single product, smaller production volume.
How are Mono-clonal antibodies made?
- Usually mouse sourced
- Mouse is immunized to human specific antigen
- Spleen cells are removed and combined with human myeloma cels
- Hybridoma cells are screened fro specific antibody with desired strength.
- Propagated in tissue culture.
Advantages:
-Single antibody is secreted, available indefinitely, highly specific and pure
Disadvantages:
-Only detects a single epitope so it can miss variables in population. It takes longer to produce initially.
Antigen-antibody binding follows the law of mass action and is always trying to reach ________
equivalence
The longevity of interaction is based on _______ and _____ of antibody.
Affinity, Avidity.
Affinity = fit
Ag ___ / ____ / _____
size, shape, charge
Overcoming:
-Steric hindrance - blocked by other particles
-Zeta potential - negative charges on red cells
Avidity = ______ of bond
strength
Examples:
-Ionic bonding (negative attract to positive)
- Hydrogren bonding (double helix DNA strands attached by hydrogens)
-Hydrophobic bonding - mutual distaste for water
-Van der Waals - attraction between neutral particles
Define Affinity
refers to the strength of a single antibody-antigen interaction
Define Avidity
refers to the strength of all interactions combined.
What are the Agglutination tests?
Immediate Spin test
-IgM antibodies form lattices without the addition of extra reagents
-Direct test
-Centrifuge / Room temp / Plasma 2:1 cells 3% w/saline
Coombs Test
-IgG antibodies form lattices with the addition of a IgM anti-IgG reagent
-requires removal of unbound material for appropriate reaction detection
-incubation at body temp (37C) increases likelihood of antibody to bind to antigen
–Enhancements are added after immediate spin, before 37 incubation to reduce zeta potential
–37C incubation
-Complement proteins attach and destroy red cells producing visual hemolysis
-IgG antibodies more likely to bind to antigen in body temp (37C)
What does LISS stand for and how is it an enhancement media?
Low ionic strength solution, it reduces zeta potential by reducing ions around red cells
How is Albumin an enhancement media?
macromolecules decreases distance between sensitized cells
What does PED stand for and how is it an enhancement media?
Polyethylene Glycol, it is a water soluble linear polymer that sucks water away from red cells to bring antibodies closer to antigens.
How is Polybrene (hexaddimethrine bromide) an enhancement media?
it is a quaternary ammonium polymer that nonspecifically binds to red cells to bring them closer for antigen/antibody binding.
A nurse just called to add on a crossmatch to a pretransfusion specimen you worked on 4 days ago. What is the most appropriate course of action?
A) Check to see if there is enough volume in the original sample to complete the workup.
B)Perform compatibility testing on the original specimen.
C) Indicate to the nurse that a new specimen needs to be collected for pre transfusion testing
D) Repeat the type and screen testing on the original sample to see if the patient has made any antibodies after transfusion.
C) Indicate to the nurse that a new specimen needs to be collected for pre transfusion testing.
Patient plasma with donor red cells produced an agglutination reaction of 1+. How do you interpret this?
A) The reaction is weak, the patient can probably tolerate the donor cells.
B) the donor blood is compatible with patient plasma
C) The donor plasma is compatible with patient blood
D)The donor blood is incompatible with patient plasma
D) The donor blood is incompatible with patient plasma
