ABID: Basic and Intermediate Flashcards
1
Q
Abs other than ABO system (Rh, Kidd, Kell, MNSs, Lewis, P1, Duffy, Lutheran)
A
Unexpected Abs
2
Q
Passively acquired Abs
A
?
3
Q
Ab screen
- ABO type
A
Group O
4
Q
Ab screen
- Required Ags to be present
A
Must have Ag positive cell for the following: D, C, E, c, e, K, k, Fya, Fyb, Jka, Jkb, Lea, Leb, P1, M, N, S, and s
5
Q
Ab screen
- Zygosity of Ags present
A
Preferably homozygous
6
Q
Ab screen
- Procedure for use of screening cells
A
2 or 3 cells used together to screen for all common unexpected clinically significant Abs
7
Q
Ab panels
- ABO type
A
Group O
8
Q
Ab panels
- Required Ags to be present
A
Cw, V, Kpa, Jsa, Lua (low frequency)
9
Q
Ab panels
- Procedure for use of panel cells
A
8-20 cells used together to give a more specific pattern of reactivity for the different Abs; will often have cells taht can detect some of the “uncommon” Abs as well as common
10
Q
How does 22% albumin aid in ABID?
A
- Disperses charges around cells, ↓ zeta potential
- Least sensitive
- Longest incubation (30-60’)
- Rarely used
11
Q
How does LISS aid in ABID?
A
- ↓ zeta potential and ↑ uptake of Ab by RBC in sensitization phase
- More sensitive than albumin, not as sensitive as PEG
- Diluent for gel methods
- 10-30’ incubation
12
Q
How does PEG aid in ABID?
A
- Removes water in system → ↑ [Ab]
- ↑ RBC sensitization
- Can cause nonspecific aggregation of cells so you can NOT centrifuge at 37C (false pos)
- More sensitive tahn LISS
- 15-30’ incubation
13
Q
How do enzymes ficin and papin aid in ABID?
A
- Removes sialic acid residues and denatures/removes glycoproteins
- Destroys some Ags and enhances others
- Always compare enzyme result to non-enzyme result
14
Q
How do DTT, 2ME, and AET aid in ABID?
A
- Disrupt the disulfide bonds of IgMs when added to serum
- Destroys Kell and Lutheran system Ags (and some HTLA Ags) when incubated w/ cells
15
Q
How do P1 and Lewis neutralization substances aid in ABID?
A
?
16
Q
State 4 general steps of ABID substances
A
- Ab detection (IAT)
- ABID → panels, patient Ag typing
- Determine clinical significance → IgM vs. IgG
- Appropriate transfusion considerations are put into place → provide Ag negative blood
17
Q
State Ab screen testing requirements according to AABB
A
Requires 37C incubation and use of Coombs
18
Q
Autocontrol
- Procedure for testing
A
1 drop patient serum/plasma + 1 drop patient’s cell suspension
19
Q
Autocontrol
- Significance of positive and negative results
A
Positive panel w/ negative AC → alloAb
Positive panel w/ positive AC → autoAb
20
Q
Autocontrol
- Correlation to the DAT
A
If AC is positive, run a DAT → should be positive
21
Q
List 5 “uncommon” Ags that may or may not be present on panel cells, but are not required to be ruled out on most panels
A
Cw, V, Kpa, Jsa, Lua
22
Q
State 3 Ag exceptions to homozygous rule-outs
A
- Kell can be ruled out heterozygously
- In presence of anti-D (you have one positive for D), anti-C and anti-E can be ruled out heterozygously w/ a negative reaction
- ?
23
Q
Predict expected Ag type of a patient when identifying alloAbs and autoAbs
A
- AlloAbs →all cells but AC will be negative
- AutoAbs → all cells including AC are positive
24
Q
Select appropriate QC cells for rare antisera testing
A
For positive control, cells must be heterozygous
25
Why is the heterozygous expression of an Ag preferred for QC of rare antisera?
Heterozygous reactions are not as strong as homozygous, if QC can pick up on heterozygosity, it can pick up anything
26
Selected panels
| - When to perform
- Once you know which Abs you have, must have 3+ cells for each Ab which are Ag neg for all of the other Abs (positive proving cells can be heterozygous or homozygous)
- Must have 3 cells that are negative for all Abs that have been ID'd
- 3+3 cells can be from Ab screen, routine panel or selected cell panel
27
Pre-warm testing
| - When to perform
To reduce or eliminate IgM cold autoAb interferences in testing
28
Pre-warm testing
| - Procedure
Pre-warmm serum and cells in separate tubes → add serum to wash cells → incubate at 37C for 30-60' → wash w/ warmed saline 3x → add IgG AHG
29
Pre-warm testing
| - Limitations
Performed at hospital BBs
30
Pre-warm testing
| - Interpretation of results
If negative, report as "cold auto/alloAb"; give XM-compatible blood using pre-warm technique
31
Enzyme-treated cells
| - When to perform
?
32
Enzyme-treated cells
| - Procedure
Removes sialic acid residues and denaturing glycoproteins
33
Enzyme-treated cells
| - Limitations
Performed at hospital BBs
34
Enzyme-treated cells
| - Interpretation of results
?
35
Neutralization
| - When to perform
When Lewis or P1 Abs are "masking" other Abs that may be underlying
36
Neutralization
| - Procedure
?
37
Neutralization
| - Limitations
?
38
Neutralization
| - Interpretation
Can be used to "prove" the Lewis or P1 Ab if pattern doesn't prove
39
Adsorptions
| - When to perform
- Presence of warm autoAbs
- Presence of known Ab to high frequency Ag → remove high Ab when looking for other underlying alloAbs
- Presence of multiple Abs
40
Adsorptions
| - Procedure
- ZZAP-treated cells for adsorption will remove bound autoAb and free up Ag sites
- ZZAP treatment of cells takes 30 minutes and then ZZAP must be washed off cells
- Usually use 2 mL packed red cells for each adsorption (4-8 mL packed red cells)
41
What is ZZAP?
A mixture of DTT which removes bound Ab
| - Destroys Ags of Kell and Lutheran systems
42
What is papin?
An enzyme which will enhance adsorption of Abs onto now open Ag sites
- Destroys Ags of Duffy and MNSs systems
43
Adsorptions
| - Limitations
Performed at reference lab
44
Adsorptions
| - Interpretation of results
?
45
Elutions
| - When to peform
To investigate Ab-coating RBCs (positive DAT) that has IgG coating cells
46
Elutions
| - Procedure
1. Wash cells to remove unbound Ab
2. Dissociate Ab from cell surface by adding acid
3. Techniques release, concentrate, and purify Ab by changing attractive forces b/w Ag-Ab or structure of RBC surface
4. Ab is freed into supernatant (eluate)
5. Prepared eluate is tested against a panel of cells just as you would serum
6. Original cells used to make eluate are discarded (can’t be used for anything else, “dead”, useless)
47
Elutions
| - Limitations
Performed at hospital BBs
48
Elutions
| - Interpretation of results
Results of eluate panel and patient history will determine cause of positive DAT
49
Titrations
| - When to perform
- Commonly used to confirm HTLA Abs
| - Quantify amount of Ab present
50
Titrations
| - Procedure
1. Prepare two-fold serial dilutions of test serum
2. Test erum dilutions against cells possessing corresponding Ag (note: use strongest expression of Ag for titer)
3. Titer endpoint is the last tube w/ 1+ reaction (when confirming HTLA Abs, endpoint may be +w or +m reaction)
51
Titrations
| - Limitations
Performed at reference lab
52
Titrations
| - Interpretation of results
?
53
DTT/2ME/AET
| - When to perform
Used to eliminate acitivty of high frequency Abs by destroying Ags on cells to whcih Abs would attach
54
DTT/2ME/AET
| - Prcoedure
After treating cells, wash off remaining DTT or 2ME then test as normal w/ patient's serum
55
DTT/2ME/AET
| - Limitations
Performed at reference lab
56
DTT/2ME/AET
| - Interpretation of results
?
57
Cell separations
| - When to perform
When patient has recently been transfused
58
Cell separations
| - Procedure
- Microhematocrit retic separation
| - Hypotonic washes for sickle cell patients
59
Microhematocrit retic separation
"Retics" from patient will be lighter/less dense than older (donor) cells and will be in top layer of spun microhematocrit
60
Hypotonic washes
Hb SS are resistant to lysis by hypotonic saline, whereas donor red cells containing Hb AA are lysed
61
Cell separations
| - Limitations
Performed at reference labs
62
Cell separations
| - Interpretation of results
?
63
EGA or CDP treatment of cells
| - When to perform
When cells have a positive DAT and need to be phenotyped
64
EGA or CDP treatment of cells
| - Procedure for EGA
EDTA glycine acid
- EGA-treated cells destroy Kell system Ags
- Can perform all other Ag typings, including AHG typings after cells have been "treated"
65
EGA or CDP treatment of cells
| - Procedure for CDP
Chloroquine diphosphate
- Does not destroy Kell system Ags
- Can only perform AHG typings (no direct typings)
66
EGA or CDP treatment of cells
| - Limitations
Performed at reference lab
67
EGA or CDP treatment of cells
| - Interpretation of results
?
68
Purpose of performing a pre-warmed technique
- May be used to reduce or eliminate IgM cold autoAb interference in testing
- No reading at IS or 37C, hence, no IgM attachement
69
Which Ags are destroyed, enhanced, and unchanged by treatment of enzymes?
Destroyed: Duffy, MNS
Enhanced: ABO, Rh, Kidd, Lewis, P, I
No change: Kell
70
Name two common blood groups for which Abs can be neutralized
Lewis and P1
71
3 adsorption techniques
- Autoadsorption
- Homologous adsorption
- Differential adsorption ("triple")
72
When is an autoadsorption used?
Removes autoAbs by incubating patient's serum w/ patient's own cells
- If patient has been recently transfused, you can't use patient's cells b/c donor cells could still be circulating
- If patient's Hct is too low, not enough cells for procedure
73
Homologous adsorption
Use of donor cells whose phenotype matches the patient (must first phenotype the patient)
74
When is homologous adsorption used?
- When autoAb is suspected but use of patient cells isn't available (patient's Hct too low to do an autoadsorption)
- Be used to remove a high frequency Ab to detect underlying alloAbs (?) ("selective" adsorption)
75
When is a differential adsorption used?
When autoadsorption and homologous adsorptions aren't an option
- Patient has been recently transfused → can't phenotype b/c of the mix of donor and patient cells
- Patient's cells have positive DAT → can't phenotype b/c DAT will cause false positive reactions for AHG typings
76
#26
?
77
Blood group systems whose Ags are destroyed by DTT/2ME/AET
Kell, Lutheran, HTLA
78
What could cause a false negative Ag typing?
?
79
What could cause a false positive Ag typing?
Postive DAT, centrifuging PEG at 37C
