Chapter 3

Tests for certain clinical conditions such as hemolytic disease of the newborn and autoimmune hemolytic anemia: a. Indirect antiglobulin test b. Direct antiglobulin test c. Both the direct and indirect antiglobulin test

b. Direct antiglobulin test

Where are product limitations and technical considerations for each reagent located? a. Standard operating procedure b. Product insert c. Food and Drug Administration code of regulations d. AABB standards

b. Product insert The product insert outlines the technical considerations, procedural guidelines, and product limitations for each reagent.

Reagent to detect the presence of red cell antibodies: a. Panel cells b. Screening cells c. A1 and B cells d. ABO antisera e. Lectins

b. Screening cells

Reagent used in the identification of ABO antibodies: a. Panel cells b. Screening cells c. A1 and B cells d. ABO antisera e. Lectins

c. A1 and B cells

Reagent antibodies prepared from human sources are: a. unsafe. b. too low in potency to be effective. c. polyclonal in specificity. d. preferred because of their lower cost.

c. polyclonal in specificity. Human-derived antisera have antibodies to multiple specificities and meet Food and Drug Administration guidelines for potency and safety.

Solid-phase red cell adherence used for antibody detection has an advantage over tube testing because: a. there is no washing involved. b. incubation time is not necessary. c. the endpoint is more clearly defined. d. indicator cells (IgG-coated cells) are not necessary

c. the endpoint is more clearly defined. Well-defined endpoints make reading results more consistent and reliable.

What immunoglobulin class reacts best by antiglobulin testing? a. IgM b. IgA c. IgE d. IgG

d. IgG The antiglobulin test detects IgG antibodies on red cells.

In the solid-phase red cell adherence test, how does a negative test appear? a. A button of cells on the bottom of the well b. Adherence of cells along the sides and bottom of the wells c. Hemolysis of red cells d. A line of cells along the top of the well

a. A button of cells on the bottom of the well Indicator cells, which are added in the final step, do not adhere to the wells and have not reacted with the antibody. Therefore, a button will form on the bottom of the well.

Select the test that uses IgG-sensitized red cells (check cells). a. Antiglobulin test b. D-antigen typing c. Rh-antigen typing d. B-antigen detection

a. Antiglobulin test The antiglobulin test requires the use of IgG-sensitized cells to verify a negative reaction was not caused by improper washing, omitting the antiglobulin reagent, or reagent problems.

Reagent to identify the specificity of a red cell antibody: a. Panel cells b. Screening cells c. A1 and B cells d. ABO antisera e. Lectins

a. Panel cells

What reagent contains antibodies to multiple antigenic epitopes? a. Polyclonal-based b. Monoclonal-based c. Heterophile antibody-based d. Alloantibody-based

a. Polyclonal-based Polyclonal reagents contain antibodies to more than one antigen specificity.

Which of the following statements is true regarding IgG-sensitized red cells? a. They must be used to confirm a negative antiglobulin tube test. b. They must be used to confirm a positive antiglobulin test. c. They must be used to confirm a direct antiglobulin test that was negative with anti-C3d. d. They should be used only with the indirect antiglobulin test.

a. They must be used to confirm a negative antiglobulin tube test. IgG-sensitized red cells are used as a control for false-negative antiglobulin tests.

Monoclonal antibodies are prepared in: a. vitro. b. vivo. c. laboratory animals. d. humans

a. vitro. Monoclonal antibodies are prepared from antibody-producing B-lymphocytes and myeloma cells in a hybridoma, which is cultured in vitro.

What temperature is used for incubation in the indirect antihuman globulin test? a. 22° C b. 37° C c. 4° C d. 56° C

b. 37° C Incubation takes place at body temperature, which is 37° C.

Which of the following red cell antigens do proteolytic enzymes destroy? a. Rh system antigens b. Antigens Fya and Fyb in the Duffy system c. Antigens in the Kidd system d. Lewis system antigens

b. Antigens Fya and Fyb in the Duffy system Proteolytic enzymes, such as ficin, will destroy some antigens on red cells such as Fya and Fyb and weaken or destroy M, N, and S.

Incubation step is not necessary: a. Indirect antiglobulin test b. Direct antiglobulin test c. Both the direct and indirect antiglobulin test

b. Direct antiglobulin test

Which red cells are used to screen for antibodies in donor samples? a. Screening cells (two vials) b. Pooled screening cells c. Panel cells d. Screening cells (three vials)

b. Pooled screening cells Pooled screening cells are acceptable for screening antibodies in donor samples.

The antiglobulin test was performed using gel technology. A button of cells was observed at the bottom of the microtube following centrifugation. How do you interpret this result? a. There is a problem with the card. b. The result is a negative reaction. c. The result is a strong positive reaction. d. The test was not washed correctly.

b. The result is a negative reaction. Red cells that are not trapped by the antihuman globulin reagent will travel unimpeded through the length of the tube.

Rouleaux is a false-positive reaction that would not likely be observed during which of the following tests? a. Immediate-spin antibody screen b. Weak D test c. Reverse typing in the ABO test d. ABO forward typing

b. Weak D test Rouleaux are caused by an elevated protein level or IV solutions and cause cells to appear agglutinated. A procedure involving washing, such as the direct or indirect antiglobulin test, would not be affected by this because saline would eliminate the excess proteins.

The gel technology method uses a concentration of red cells that is: a. higher than tube techniques. b. lower than tube techniques. c. the same as the 3% to 5% requirement for tube testing. d. variable according to the test performed

b. lower than tube techniques The gel method uses a 0.8% suspension of red cells.

Following centrifugation of the gel card, red cells are evenly dispersed throughout one of the microtubes. This reaction could be graded as a: a. 4+. b. 3+. c. 2+. d. 1+.

c. 2+. A 2+ reaction is demonstrated with red cells throughout the microtube.

What specificities does polyspecific antihuman globulin contain? a. Anti-IgG. b. Anti-C3b and anti-C3d. c. Anti-IgG and anti-C3d. d. Anti-IgG and anti-IgM.

c. Anti-IgG and anti-C3d. Polyspecific antihuman globulin contains specificities to the heavy chain IgG and complement component, C3d.

Detects IgG or complement-coated red cells: a. Indirect antiglobulin test b. Direct antiglobulin test c. Both the direct and indirect antiglobulin test

c. Both the direct and indirect antiglobulin test

Requires washing the cells several times before the addition of antihuman globulin reagent: a. Indirect antiglobulin test b. Direct antiglobulin test c. Both the direct and indirect antiglobulin test

c. Both the direct and indirect antiglobulin test

What is the purpose of adding antibody-sensitized red cells following the antiglobulin test? a. Ensure a weak antibody reaction was not missed b. Confirm positive reactions c. Check that the wash procedure was sufficient to remove unbound antibodies d. Check that sufficient incubation took place

c. Check that the wash procedure was sufficient to remove unbound antibodies Antibody-sensitized red cells (check cells) are IgG-coated cells that will detect unbound antihuman globulin following proper washing techniques.

Select the method that uses a dextran-acrylamide matrix. a. Solid-phase red cell adherence b. Microplate c. Gel technology d. Tube techniques

c. Gel technology The dextran-acrylamide gel matrix traps agglutinated cells, making antigen-antibody reactions visible.

Why is polyethylene glycol reagent added to the screen or panel? a. Enhance detection of IgM antibodies. b. Eliminate the reactivity of certain antigens. c. Increase the avidity of IgG antibodies. d. Eliminate the need for washing in the indirect antiglobulin test.

c. Increase the avidity of IgG antibodies. Polyethylene glycol (PEG) concentrates antibodies and increases the rate of antibody uptake, increasing the avidity of IgG antibody reactions.

Why is incubation omitted in the direct antihuman globulin test? a. The direct antiglobulin test can be used in an emergency to replace the indirect test. b. Incubation will cause hemolysis. c. The antigen-antibody complex has already formed in vivo. d. IgM antibodies are detected in the direct antiglobulin test.

c. The antigen-antibody complex has already formed in vivo. Incubation of the antigen-antibody complex essentially has taken place within the patient (or donor), making additional incubation in the tube unnecessary.

How would you interpret the results if both the anti-D reagent and the Rh control were 2+ agglutination reactions? a. D-positive b. D-negative c. Unable to determine without further testing d. Depends on whether the sample was from a patient or a blood donor

c. Unable to determine without further testing The Rh control should be negative for the test to be valid.

Reagent used to determine the ABO antigenic composition of a patient's red cells: a. Panel cells b. Screening cells c. A1 and B cells d. ABO antisera e. Lectins

d. ABO antisera

Which of the following items provides evidence for reagent red cell deterioration? a. Spontaneous agglutination b. Significant hemolysis c. Loss of agglutination strength over time d. All of the above

d. All of the above Each observation listed may indicate a reagent red cell problem that could lead to false reactions

Which of the following statements is true regarding high-protein anti-D reagents? a. They have been largely replaced with low-protein monoclonal reagents. b. They contain approximately 20% bovine albumin. c. They may increase the possibility of a false-positive reaction, requiring the use of a control. d. All of the above are true.

d. All of the above are true. High-protein anti-D reagent requires the use of a control to verify that positive reactions are the result of an antigen-antibody reaction and not agglutination caused by the reagent additive. For this reason, the use of monoclonal anti-D is more commonly used.

Which of the following is not an advantage of using a monoclonal antibody over a polyclonal antibody? a. There are very few variations between lots. b. There are no contaminating antibodies. c. Direct agglutination is usually faster. d. All variations of the antigen can be detected

d. All variations of the antigen can be detected Some monoclonal D antibodies may miss antigen variations, such as the partial D phenotype.

Reagent derived from plants used to distinguish group A1 from group A2 red cells: a. Panel cells b. Screening cells c. A1 and B cells d. ABO antisera e. Lectins

e. Lectins