Antibody Identification and Crossmatch

Question 1

3 goals of Crossmatch as defined by AABB Technical Manual

Answer 1

1. 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

Question 2

1 rule before transfusion

Answer 2

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

Question 3

AABB standards require for ABO and Rh discrepancies

Answer 3

-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.

Question 4

Standards require-previous records

Answer 4

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

Question 5

Standards require for selection of appropriate ABO/Rh component units for recipient

Answer 5

1. 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.

Question 6

Standards for distribution of Rh negative blood

Answer 6

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

Question 7

Major Crossmatch

Answer 7

patient serum+ donor cells

Question 8

Minor crossmatch

Answer 8

patient rbcs+ donor serum

Question 9

Standards for two determinations of recipients ABORH

Answer 9

one current ant one: 1. Retest of the same sample 2. Testing a second sample 3. comparison to historical records

Question 10

What antigens are applicable for a single rule out on ABID

Answer 10

D, K, P1, Xga

Question 11

Antigens with low frequency that can be initially omitted

Answer 11

Vel, Kpa, Jsa, Lua, Cw

Question 12

If anti-D is detected what exceptions apply

Answer 12

Ruling out C on a heterozygous and ruling out a E on a heterozygous cell

Question 13

what cell is needed to rule out and anti-E in a patient that has anti-c

Answer 13

RZRZ

Question 14

what cell is needed to rule out anti-C in a patient that has anti-e

Answer 14

RZRZ

Question 15

Which antigens does the double dose not apply to?

Answer 15

Lewis, the two are not antithetical to one another,P1 does not have and antithetical parter, Xga and D

Question 16

Rule in and rule outs:

Answer 16

AABB IRL: 2 pos and 2 neg

Question 17

Proteolytic Enzymes Destroy

Answer 17

M, N, S, s, Fya, Fyb, Xga

Question 18

Proteolytic enzymes enhance

Answer 18

Rh, Kidd, Lewis, P1, I, WAA

Question 19

Denaturation Tests

Answer 19

EGA, Chloroquine diphosphate

Question 20

Testing older commercial cells is good for

Answer 20

HTLA antibodies

Question 21

Unaffected by enzymes

Answer 21

Kel, Diego and Colton

Question 22

In testing cord cells, what CD marker is present

Answer 22

CD34

Question 23

Isohemagglutinins

Answer 23

IgM anti-A and anti-B present

Question 24

If crossmatch is incompatible what are the rare reasons for this?

Answer 24

Donor red cells ABO-incompatile, Donor red cells are polyagglutinable, passively acquired anti-A or anti-B (from plasma or platelets)

Question 25

P1 neutralization

Answer 25

hydatid cyst fluid, pigeon egg whites

Question 26

Lewis neutralization/inhibition

Answer 26

present in the serum of secretors (Lea-Leb+) individuals will inhibit anti- Lea or Leb

Question 27

CH/RG neutralization/inhibition

Answer 27

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

Question 28

Sda+ neutralization

Answer 28

urine has high concentrations of Sda antigen. mixed together anti-Sda is neutralized

Question 29

HTLA

Answer 29

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

Question 30

HTLA mimic antibodies

Answer 30

Lutheran B, Hy and Yta - do cause shortened red cell survival, can mimic HTLA antibodies

Question 31

Anti-C38

Answer 31

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

Question 32

Titration for separating multiple antibodies

Answer 32

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.

Question 33

Heat or freeze-thaw elutions

Answer 33

typically used for ABO HDFN investigation because these elution procedures don’t work well for recovering other antibodies.

Question 34

elution techniques are useful for:

Answer 34

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 .

Question 35

Elution problems: dissociation of antibody before elution

Answer 35

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

Question 36

Elution problems:incorrect technique

Answer 36

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’