Detection and Identification of Antibodies (Exam 2)

The degree of reactivity at ______ of testing is graded.

all phases

The gel method of antibody screening involves a microtubule filled with a ______ gel.

dextran acrylamide

The screen cells used in the gel method must be a ______ suspension.

0.8%

The solid phase adherence method for antibody screen uses red cell adherence to ______ to aid in antibody capture.

microtiter wells

Agglutination or hemolysis at an stage of antibody screen testing is a ______ test result.

positive

What are some limitations to antibody screening?

- Antibody titer below the level of sensitivity

-Low prevalence antigens and antibodies

- Lack of homozygous expression of the target antigen on screening cells (dosage)

What factors influence antibody screen sensitivity?

- Cell:serum ratio

- Temperature and phase of reactivity

- Length of incubation and pH

A positive antibody screen requires additional testing to ______ the antibody and determine its clinical significance.

identify

This involves testing against additional RBCs possessing ______.

known antigens

An antibody identification panel is a collection of 11-20 group ______ RBCs with various antigen expression.

O

Antibody identification panels should include cells with homozygous expression of ...

- Rh

- Duffy

- Kidd

- MNSs

The focus of antibody detection methods is on ______ antibodies.

unexpected

The most important antibodies in Ab ID are ______.

immune alloantibodies

Immune alloantibodies are produced in response to ...

- Transfusion

- Transplantation

- Pregnancy

What are the types of naturally occurring antibodies?

- Immune alloantibodies

- Naturally occurring antibodies

- Passively acquired antibodies

- Autoantibodies

Autoantibodies can mask underlying ______.

alloantibodies

The first hint that a patient has an autoantibody is the ______.

auto-control

Unexpected antibodies may complicate the ______ of clinically significant antibodies.

detection

Clinically significant means that the antibodies decrease the ______ of RBCs possessing the target antigen.

survival

These clinically significant antibodies can cause ...

- Hemolytic transfusion reactions

- HDFN

Clinically significant antibodies are typically ______.

IgG (warm)

Antibody screen is included in ______ testing and for ______ transplant donors/recipients.

prenatal, BM/SC

The traditional method of detecting clinically significant antibodies is the ______ method.

tube

The tube method for antibody screen is an ______ antiglobulin test.

indirect

Using the tube method for antibody screen, ______ from group O individuals are packaged in sets of 2 or 3 cell suspensions.

screen cells

Each set of screen cells is accompanied by an ______ detailing which antigens are present in each vial of cells.

antigen profile sheet (antigram)

Homozygous cells exhibit a ______ dose of antigen.

double

Antibodies that react more strongly with cells having homozygous antigen expression are said to show ______.

dosage

What common blood groups exhibit dosage?

- Rh (not D)

- Kidd

- Duffy

- MNSs

- Lutheran

______ may be added to the cell/serum mixture before the 37C incubation phase of the tube antibody screen method.

Enhancement reagents (potentiators)

Potentiators help increase the ______ of the test system.

sensitivity

What are some potentiators?

- 22% albumin

- LISS

- PEG

______ reagents are important in tube antibody screening, and can be monospecific/polyspecific.

Antihuman globulin (AHG)

IgG coated ______ cells are used in order to show agglutination presence.

control

The immediate spin phase of the tube antibody screen method is ______ (required/not required).

not required

Depending on the enhancement added, the antibody screen tubes may be centrifuged and observed for ______ and ______ following incubation.

hemolysis, agglutination

The ______ phase of tube antibody screening is always done.

37C incubation

Check cells are added to all ______ AHG phase tubes.

negative

To have a valid test, the check cells must ______.

agglutinate

In antibody identification, ______ antibodies that could not be responsible for the reactivity seen.

exclude (rule out)

After each negatively reacting cell has been evaluated, the remaining antigens should be examined to see if the pattern of reactivity matches a pattern of ______ cells.

antigen positive

The rule of 3 states that there must be at least 3 ______ to rule an antibody out.

positive cells

If a patient has a positive ______ or has been ______ in the past 3 month, you cannot accurately phenotype their RBCs.

DAT, transfused

What can be used to fix a positive DAT in a patient?

- Acid glycine/EDTA (EGA)

- Chloroquine diphosphate

______ can be used to make a recent transfusion not interfere with phenotyping.

Reticulocyte separation

______ additional cells can be a technique used to help with rule ins/outs.

Hand selecting

Cherry-picking additional cells can also be used when a patient has a history of a ______ antibody and you must exclude all other significant antibodies.

known

Enzymes are helpful in ______ multiple antibodies present in a sample.

separating

What are some enzymes that can be used for this?

- Ficin

- Papain

- Bromelin

- Trypsin

Enzymes will modify the RBC surface by removing ______ residues and by ______ glycoproteins.

sialic acid, denaturing/removing

Neutralization allows for ______ of antibodies or confirmation that an antibody is present.

separation

Anti-P1 comes from ...

Hydatid cyst fluid, egg whites

Anti-Lewis comes from ...

plasma, saliva

Anti-Sda comes from ______.

urine

Antibodies may be removed from plasma by adding the ______ and allowing for antibody binding.

target antigen

This is referred to as ______.

adsorption

Adsorbed plasma can be tested for the presence of ______.

"unadsorbed" alloantibodies

What are the types of adsorption?

Autoadsorption, alloadsorption, phenotypically matched adsorption

A DAT is used to to detect ______ sensitization of RBCs.

in-vivo

DAT is used for detection of ______ or ______ coating RBCs.

antibodies, complement

DATs are helpful to investigate ...

- Suspected hemolyic txn reactions

- HDFN

- Autoimmune and drug-induced hemolytic anemias

If a DAT is positive for IgG antibody, you must ______ antibodies coating the RBC surface to allow for identification.

dissociate (remove)

What are some elution techniques for positive DAT?

- Temperature-dependent methods (heat or freeze-thaw)

- pH adjustment (acid)

- Organic solvents

Antibody titration quantifies the ______ of antibody present.

amount

Antibody titration consists of two-fold serial dilutions of ______ tested against a suspension of ______ possessing the target antigen.

serum, RBCs

What levels of antibody titration are significant?

- Four-fold or greater increase in titer

- Increase in score of 10 or more

What are some clinical applications of antibody titration?

- HDFN

- Differentiation of immune anti-D from passively acquired anti-D due to RhIG administration

- Confirm the presence of antibodies previously known as HTLA (high titer, low avidity)

- List patients as eligible for incompatible transplants

When providing compatible blood products, consider the antigen ______.

frequency (in population)

You must also consider the ______ of the antibody.

clinical significance

Units must be antigen ______ if a clinically significant antibody is present or there is pt history of them.

negative

Clinically significant antibodies must be compatible at the ______ phase.

AHG

Patients with sickle cell or beta-thalassemia receive transfusions ______.

chronically

These patients are more likely to form ______.

alloantibodies

In this case, you must give ______ pRBCs to prevent the formation of alloantibodies, specifically for Rh and K antigens.

phenotypically-matched

Compatibility formula

y = x/combined frequency of antigen negative units

If 64% of donors are compatible with a recipient, how many units would have to be tested to find 4 compatible units?

y = 4/0.64 = 6.2 (round up to 7)

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