AHG Flashcards
what is the antiglobilin test known as
Coombs test
what immunoglobin has to be on RBC for agglutination to be visible in a Coombs test
IgG
what animal does anti-human globulin come from
rabbits
what does AHG bind to during a Coombs test
human immunoglobulins
what kind of antiglobulin test measures in vivo sensitization of RBC
direct
what kind of antiglobulin test measures in vitro sensitization of RBC
indirect
what is an example of an indirect anti globulin test
ab screen test
what kind of sample is used in a indirect Antiglobulin test
serum
during a direct antiglobulin test what does the reagent detect
IgG or C’
in a direct antiglobulin test what are the RBC washed with
saline
what needs to be added if a neg Coombs test is received
checked cells
what do checked cells verify
adequate washing, Anti-human globulin was added and working
after checked cells are added and a pos test is recored what does this mean
test is valid
after checked cells are added and a neg test is recored what does this mean
test is invalid and must be repeated
if a pos direct antiglobulin test uses poly specific AHG what need to be done
repeat using monospecific AHG reagent
what can cause the AHG reagent to become contaminated
putting vial in pt sample
what is detected in an indirect antiglobulin test
irregular abs in recipient sera
what is another name for Coombs reagent
antihuman globulin
what color is poly specific AHG reagent
clear
what does ploy specific AHG contain
abs to human IgG and human C3d
what is an advantage of polyspecific AHG
detects C’ binding Abs on RBC
what is an disadvantage of polyspecific AHG
detects C’ on cells that may not be clinically sig
what is the color of IgG monospecific AHG
green
what does IgG monospecific AHG contain
abs to human IgG only
what color is C3d monospecific AHG
clear
what size is C3d monospecific AHG
small
what does C3d monospecific AHG contain
abs to human C3d only
what is an advantage of monospecific AHG
fewer nuisance pos
who regulates Coombs reagents
FDA
what do CC reagent contain
regent RBC coated with IgG
A description of the antiglobulin test is:
AHG reacts with human globulin molecules bound to RBCs
Polyspecific AHG reagent contains:
Anti-IgG and anti-C3d.
Monoclonal anti-C3d is Derived from
one clone of plasma cells.
Which of the following is a clinically significant antibody whose detection has been reported in some instances to be dependent on anticomplement activity in polyspecific AHG?
anti-Jk a
After the addition of IgG-coated RBCs (check cells) to a negative AHG reaction during an antibody screen, a negative result is observed. Which of the following is a correct interpretation based on these findings?
The antibody screen cannot be interpreted.
RBCs must be washed in saline at least three times before the addition of AHG reagent to:
Remove traces of free serum globulins.
An in vivo phenomenon associated with a positive is:
Maternal antibody coating fetal RBCs.
False-positive DAT results are most often associated with:
Use of refrigerated, clotted blood samples in which complement components coat RBCs in vitro.
Polyethylene glycol (PEG) enhances antigen-antibody reactions by:
Concentrating antibody by removing water.
Solid-phase antibody screening is based on:
Adherence
A positive DAT may be found in which of the following situations
HDFN
What do Coombs’ check cells consist of?
Type O-positive cells coated with anti-D
Which of the following IAT methods requires the use of check cells?
Manual tube method with albumin
Which uncontrollable factor can affect AHG testing?
Incubation time
Which would be the most efficient method for a laboratory staffed by medical laboratory technicians?
Polybrene
A 27-year-old group O mother has just given birth to a group A baby. Since the mother has IgG anti-A, anti-B and anti-A, B in her plasma, which of the following methods and tests would be most effective at detecting the anti-A on the baby’s RBCs?
IAT using gel
