Chapter 5 The Antiglobulin Test
False-positive DAT results are most often associated with: a. Use of refrigerated, clotted blood samples in which complement components coat RBCs in vitro. b. A recipient of a recent transfusion manifesting an immune response to recently transfused RBCs. c. Presence of antispecies antibodies from administration of immune globulin (IVIG). d. A positive autocontrol caused by polyagglutination.
a
Monoclonal anti-C3d is: a. Derived from one clone of plasma cells. b. Derived from multiple clones of plasma cells. c. Derived from immunization of rabbits. d. Reactive with C3b and C3d
a
Solid-phase antibody screening is based on: a. Adherence. b. Agglutination. c. Hemolysis. d. Precipitation.
a
Which of the following IAT methods requires the use of check cells? a. Manual tube method with albumin b. Gel c. Automated solid-phase analyzer d. Enzyme-linked
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? a. The antibody screen is negative. b. The antibody screen cannot be interpreted. c. The saline washings were adequate. d. AHG reagent was added.
b
Polyethylene glycol (PEG) enhances antigenantibody reactions by: a. Decreasing zeta potential. b. Concentrating antibody by removing water. c. Increasing antibody affinity for antigen. d. Increasing antibody specificity for antigen.
b
RBCs must be washed in saline at least three times before the addition of AHG reagent to: a. Wash away any hemolyzed cells. b. Remove traces of free serum globulins. c. Neutralize any excess AHG reagent. d. Increase the antibody binding to antigen
b
Which would be the most efficient method for a laboratory staffed by medical laboratory technicians? a. LISS b. Polybrene c. Solid-phase or gel d. Enzyme-linked
b
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? a. DAT using common tube technique b. DAT using gel c. IAT using common tube technique d. IAT using gel
d
A description of the antiglobulin test is: a. IgG and C3d are required for RBC sensitization. b. Human globulin is completely eluted from RBCs during saline washings. c. Human globulin is injected into an animal. d. AHG reacts with human globulin molecules bound to RBCs.
d
An in vivo phenomenon associated with a positive DAT is: a. Passive anti-D detected in the maternal sample. b. Positive antibody screen tested by LISS. c. Identification of alloantibody specificity using a panel of reagent RBCs. d. Maternal antibody coating fetal RBCs
d
Which uncontrollable factor can affect AHG testing? a. Temperature b. Antibody affinity c. Gravitational force in the centrifuge d. Incubation time
d
A positive DAT may be found in which of the following situations? a. A weak D-positive patient b. A patient with anti-M c. HDFN d. An incompatible crossmatch
c
Polyspecific AHG reagent contains: a. Anti-IgG and anti-IgA. b. Anti-IgG and anti-IgM. c. Anti-IgG and anti-C3d. d. Anti-IgA and Anti-C3d
c
What do Coombs' check cells consist of? a. Type A-positive cells coated with anti-IgG b. Type A-negative cells coated with anti-IgG c. Type O-positive cells coated with anti-D d. Type B-negative cells coated with anti-D
c