Serology Flashcards
Objective
Give agglutination reaction grade
0
negative, no agglutination
Cells remove from cell button as smoke or cloud
Objective
Give agglutination reaction grade
3+
Many large agglutinates in clear background. As cell button is shaken, agglutinates remove easily in large chunks
Objective
Give agglutination reaction grade
1+
Very small agglutinates. Come off as cookie bites from button
Objective
Give agglutination reaction grade
4+
Solid agglutination
Cells stick together into one solid chunk floating in liquid background
Objective
Give agglutination reaction grade
2+
Many small agglutinates in clear background.
Agglutinates appear to crumble off into solution
Objective
How do you interpret results of serologic reactivity in determining the presence or absence of Ag on patient RBCs or Ab in patient’s plasma?
- Positive or Negative
- Incompatible or Compatible
Word of the day
Monoclonal
Antibodies usually mouse-sourced that come from single clone of hybridoma cells
How do you get monoclonal antibodies?
- Immunize mouse with human specific Ag
- Remove spleen cells and combine B cells with human myeloma cells
- Hybridoma cells screened for antibody
- One clone selected and propagated in tissue culture
Advantages of mAbs?
Single ant
Single Ab secreted is available forever, highly specific, and pure
Disadvantages of mAbs?
- Only detects single epitope so can miss variables in population
- Initially takes longer to produce
Incidence
% frequency of Ag present in population in population frequency chart
High incidence
More than 90%
Low incidence
Less than 10%
Ag phenotypic testing
Serology where you use anti-sera to ID RBC Ag
T/F
A person makes an Ab for an Ag they do have on RBCs
False
People make Ab for Ag they don’t have on RBCs. Antithetical Ag does not matter
What population frequency of Ag indicates compatible blood?
100%
Antibody ID method
Use known cells to ID unknown Ab
What is the #1 cause of a transfusion reaction?
Data entry error
Document control regulations
- All test results must be recorded as they are tested, don’t wait to record even if you don’t think what you see is right
- All data entry needs 2nd tech to review
- Consult procedures before discarding. Strict guidelines for how long docs are kept
- All original docs must be legible and in permanent pen. Single line cross-out errors followed by date and initials accepted
Sample labels
- 2 pt identifiers
- date/time of collection
- collector name
- secondary ID method if necessary (armband or 2nd specimen)
When do you reject a hemolyzed sample?
Moderate hemolysis
hemolysis >= 200 mg/dl
How do you maintain sample integrity?
- EDTA preferred, centrifuged to separate from plasma
- No gel separator or hemolysis
- Appropriate labeling
- Enough volume to perform testing
Causes of hemolysis?
- Already occurring in pt or due to blood draw
- Hemolysis can indicate positive reaction in blood bank testing (but it’s bad)
Patient history to look for (compare records to current results and investigate/resolve discrepancies before issuing unit for transfusion)
- ABO/Rh type
- Difficult blood typing
- Clinically significant Ab
- Adverse events to transfusion
- Special transfusion requirements
Explain the 3-day rule
- Pre-transfusion testing must be done within 72 hrs after collection
- Day 0 is draw day
How long are samples retained post-transfusion and why that length of time?
7 days
bc pt may show transfusion reaction after 7 days
Why might you draw blood before transfusion?
- If pt was transfused in the preceding 3 months with allogenic cells (from different person)
- If pt was pregnant in preceding 3 months
- If history is uncertain/unavailable
T/F
There shall be 2 determinations of the recipient’s ABO/Rh type
True
Compare pt serological results to another copy of that pt
T/F
Manager must monitor QC at least annually
False
Monthly
Temps critical for equipment need to be monitored how often?
At least daily
How often must storage device alarms be tested?
At least quarterly before store products go out of acceptable limits
Centrifuge calibration is performed how often?
At least bi-annually
Rpms and tachometers are tested how often?
Quarterly
Daily QC
- Run before pt testing
- Tests reagents before use
- Manual reagents run on daily basis in typical method: IS or AHG (blood type, antibody screen)
Non-routine QC
- Run with pt testing
- Tests the test system
- May have to consult package insult for instructions
- Reagents used for specific test (phenotyping anti-sera, neutralization test, fetal screen)
anti-A color?
Blue
anti-B color?
Yellow
anti-D color?
Clear
anti-G color?
May or may not be green
Blood mixture % for tube and gel testing
- Tube: 3% cells to saline
- Gel: 0.8% cells to saline
Screen and panel cells come from what kind of human donor?
Type O
Reverse cells come from what kind of human donor?
Multiple human donors
Ab and RBC storage
2-10°C
Look for growth, abnormal color, hemolysis in cells
Describe first reagents
- Entirely from human donors
- Drawbacks: donor safety,, difficult to create in bulk, non-specific
- Donors were hyper-immunized to get better results
Polyclonal Ab
Made from multiple plasma cell sources to detect multiple sites on same Ag
Poly-specific Ab
Ab mix that detects multiple Ag or detects same Ag in different ways (IgG and IgM) to give one result
How are polyclonal Ab made?
- Immunize rabbit against desired Ag
- Purify rabbit serum for desired Ab
Advantage of polyclonal Ab
More likely to react with Ag bc it detects more Ag sites
Disadvantages of polyclonal Ab
- Non-specific reactivity possible
- Non-standardized
- Hard to determine potency of single product
- Smaller production volume
Prozone phenomonen
Ab excess
Postzone phenomenon
Ag (RBC) excess
Affinity
Fit of single Ab on Ag
Overcomes steric hindrance and zeta potential
Avidity
Multimeric bonds (ionic, H-bond, hydrophobic bonds, van der Waals)
Immediate spin test
- IgM Ab form lattices without addition of extra reagents
- Direct test
- Centrifugation brings reactants close together
- Room temp
- Plasma 2
Agglutination testes that require 37°C incubation
Complement and IgG
Coombs test
When and why are enhancements added to Coombs test?
- LISS, albumin, PEG may be added after immediate spin and before 37°C inc to reduce zeta potential (negative charge), thus bringing RBCs closer together
- Enzymes reduce steric hindrance of interfering Ag
Low ionic strength solution (LISS)
Reduces zeta potential by reducing ions around red cells, thus allowing RBCS to come closer and form lattice
Albumin as enhancement agent
Protein decreases distance between sensitized cells
Polyethylene glycol (PEG)
Water-soluble linear polymer sucks water away from RBCs to bring Ab closer to Ag
Polybrene (hexadimethrine bromide)
Quarternary ammonium polymer that non-specifically binds RBCS to bring them closer for Ag-Ab binding
