Antibody Identification and Crossmatch Flashcards
3 goals of Crossmatch as defined by AABB Technical Manual
- Detect as many clinically significant antibodies as possible 2. Detect as few clinically insignificant antibodies as possible 3. Complete the procedure in a timely manner
1 rule before transfusion
check the patient’s identity and ensure that the information is correct, this is the #1 reason for hemolytic transfusion reactions are due to erors in patient or sample identification
AABB standards require for ABO and Rh discrepancies
-If the descrepancy can not be resolved before the patient needs the transfusion type O blood should be given. If problems arise within the D testing, Rh Negative blood should be given.
Standards require-previous records
Check and compare to current result: 1. Previous history of ABO/Rh 2. Difficulty in blood typing 3. Clinically significant antibodies have been detected in the past 4. significant adverse events to transfusion 5. special transfusion requirements (CMV- etc) Any history of clinically significant antibodies dictates an AHG phase crossmatch
Standards require for selection of appropriate ABO/Rh component units for recipient
- First choice is the same ABO/Rh type 2. Transfused donor red cells must be ABO compatible with the patient’s plasma and whatever antibodies may be present 3. Transfused plasma must be ABO compatilbe with the recipients red cells.
Standards for distribution of Rh negative blood
Rh positive blood should ge given to Rh-positive individuals and Rh-negative units should be reserved for Rh negative individuals. The physician needs to be involved in any decisions related to giving RH-Positive blood to an Rh-negative person. >50-80% chance of making an anti-D
Major Crossmatch
patient serum+ donor cells
Minor crossmatch
patient rbcs+ donor serum
Standards for two determinations of recipients ABORH
one current ant one: 1. Retest of the same sample 2. Testing a second sample 3. comparison to historical records
What antigens are applicable for a single rule out on ABID
D, K, P1, Xga
Antigens with low frequency that can be initially omitted
Vel, Kpa, Jsa, Lua, Cw
If anti-D is detected what exceptions apply
Ruling out C on a heterozygous and ruling out a E on a heterozygous cell
what cell is needed to rule out and anti-E in a patient that has anti-c
RZRZ
what cell is needed to rule out anti-C in a patient that has anti-e
RZRZ
Which antigens does the double dose not apply to?
Lewis, the two are not antithetical to one another,P1 does not have and antithetical parter, Xga and D
Rule in and rule outs:
AABB IRL: 2 pos and 2 neg
Proteolytic Enzymes Destroy
M, N, S, s, Fya, Fyb, Xga
Proteolytic enzymes enhance
Rh, Kidd, Lewis, P1, I, WAA
Denaturation Tests
EGA, Chloroquine diphosphate
Testing older commercial cells is good for
HTLA antibodies
Unaffected by enzymes
Kel, Diego and Colton
In testing cord cells, what CD marker is present
CD34
Isohemagglutinins
IgM anti-A and anti-B present
If crossmatch is incompatible what are the rare reasons for this?
Donor red cells ABO-incompatile, Donor red cells are polyagglutinable, passively acquired anti-A or anti-B (from plasma or platelets)
P1 neutralization
hydatid cyst fluid, pigeon egg whites
Lewis neutralization/inhibition
present in the serum of secretors (Lea-Leb+) individuals will inhibit anti- Lea or Leb
CH/RG neutralization/inhibition
serum contains complement C4 will neutralize. NOT AN INHIBITION technique but soluble CH and Rg in plasma can also be used to coat RBCs in vitro with C4d- these coated red cells will immediately agglutinate with anti-Ch/anti-Rg and eliminate the need for inhibition study
Sda+ neutralization
urine has high concentrations of Sda antigen. mixed together anti-Sda is neutralized
HTLA
high titer low avidity terminology not used anymore- react weakly when undiluted, continue to react at dilutions as high as 1:2048 (chido, rogers, Csa, Yka, Knopsa, McCa and JMH) don’t typically cause shortened red cell survival
HTLA mimic antibodies
Lutheran B, Hy and Yta - do cause shortened red cell survival, can mimic HTLA antibodies
Anti-C38
can show high titered reactivity and is generally not reactive with Lua-Lub- cells- if drug is not disclosed to the lab staff it may be concluded that this is an antibody to high incidence lutheran antigen. daratumumab is anti-CD38 therapy for multiple myeloma
Titration for separating multiple antibodies
if antibodies react different at different dilutions (titers) you can dilute the sample and effectively remove the reactions of the one antibody and reveal the other.
Heat or freeze-thaw elutions
typically used for ABO HDFN investigation because these elution procedures don’t work well for recovering other antibodies.
elution techniques are useful for:
investigation of a positive DAT result, concentration and purification of antibodies, detection of weakly expressed antigens (adsorption elution) and identification of multiple antibody specificities, and preparation of antibody-free red cells for autologous adsorption properties .
Elution problems: dissociation of antibody before elution
Certain antibodies that are weakly bound can dissociate from red cells, to minimize loss of bound antibody, cold saline or wash solution provided by elute manufacturer should be used for washing
Elution problems:incorrect technique
incomplete removal of organic solvents or failure to correct the tonicity or pH of an eluate may vause reagent red cells to appear sticky or become hemolyzed due presence of ‘stromal debris’
