Exam I Practice Quiz 1
All of the following are true regarding IgM antibodies
-IgM is 160 Å larger than IgG. -IgM can bind to up to 10 antigens on a red cell. -IgM is a pentamer.
What is a possible explanation for a weak reaction (1+) in a reverse ABO grouping test?
-Immunocompromised patient -IgM deficiency -Elderly patient
All of the following are characteristics of monoclonal reagents
-monoclonal antibodies with high affinities. -antibodies directed against a single epitope. -an absence of batch variation.
All of the following techniques are used in the laboratory to detect blood group antigens or antibodies
-precipitation. -agglutination. -hemolysis.
All of the following are characteristics of a secondary immune response
-quickly formed antibodies. -lower dose of antigen required to form antibodies. -higher avidity for antigen.
At what temperature do IgM antibodies react?
22°C (room temp.)
At what temperature do IgG antibodies react optimally?
37°C
At what age do infants begin to produce their own antibodies?
4-6 months
What does hemolysis represent in an antigen-antibody reaction?
A positive result
Which blood group antibodies are known to activate complement, leading to intravascular hemolysis?
ABO
What test is used to remove autoantibodies from test serum?
Adsorption
Which of the following are produced after exposure to genetically different nonself antigens of the same species?
Alloantibodies
What does polyspecific AHG contain?
Anti-IgG, -C3b, -C3d
How is the classical pathway of complement activated?
By binding of antigen with antibody
Why is EDTA not conducive to complement activation?
Calcium is inactivated
What MHC Class encodes complement components?
Class III
Only 5% of Kell-negative individuals will develop antibodies to Kell if exposed to the Kell antigen, whereas 50% to 70% of Rh(D)-negative individuals would produce antibodies to D upon exposure. What is the reason for this?
Difference in immunogenicity
What function does chemically modified IgG serve?
Disulfide bonds are reduced in the hinge region of IgG, which promotes flexibility of Fab portions.
A person with the genotype MM shows a 3+ reaction when red blood cells are mixed with M antisera, whereas a person with the genotype MN shows a 1+ reaction. What phenomenon is occurring here?
Dosage
Which antibodies characteristically demonstrate a decreased avidity for antigen?
HTLA
What class of immunoglobulin is capable of crossing the placenta?
IgG
Which of the following antibodies is considered the most significant in blood banking because it reacts at body temperature?
IgG
Which IgG subclass primarily comprises antibodies to the Rh blood group system?
IgG1, IgG3
Anti JK (Kidd) antibodies are of what class of antibody?
IgG3
When there is an excess of antigen in a serologic test system, what course of action should be followed?
Increase the serum-to-cell ratio
What is the purpose of the antihuman globulin (AHG) test in blood banking?
It detects red blood cells coated with antibody by bridging the gap between red blood cells.
In an immune response, what is the time called during which no antibody is detected in the test serum?
Latency period
Which of the following blood group systems is not likely to cause HDN?
MN
What cells are responsible for mounting a secondary response when exposure to the same antigen occurs?
Memory T/B cells
Which of the following is not true of monoclonal reagents?
Monoclonal reagents are produced for single antigens with more than one epitope.
IgG-coated RBCs will be phagocytized by what effector cells?
Monocytes/macrophages
Extravascular hemolysis occurs when red blood cells are coated with antibody; what organ sequesters these cells?
Reticuloendothelial system
What Rh type does a mother have to be to produce antibodies to Rh(D) from an Rh-positive infant?
Rh-negative
A patient with multiple myeloma exhibits rouleaux formation in an immediate spin crossmatch. What procedure is recommended to distinguish true red blood cell agglutination from nonspecific agglutination?
Saline replacement
Why are enzymes used in blood banking?
Sialic acid is released from red blood cells, which helps to reduce the zeta potential.
What does the term zeta potential mean?
The attraction of negative charges on the surface of red blood cells to positive charges in an ionic cloud
An agglutination inhibition test is performed on a person whose blood type is A+. The person's saliva is mixed with type A antisera. After incubation, the solution is mixed with reagent A cells and no agglutination occurs. What can be deduced from this finding?
The person is a secretor of A substance
Which is a characteristic of natural killer (NK) cells?
They bind to and lyse antibody-coated cells in ADCC.
What is responsible for recognition of the antibody-binding site to homologous antigen?
Variable region of light/heavy chain
When antigen and antibody combine, they are held together by noncovalent forces. With the absence of a visible lattice, this stage is called ___________.
sensitization