Deck 10: Precipitation and Particle Agglutination Methods

Question 1

If a slide agglutination test is rotated for less than 1 minute, as the directions specify, what source of error can occur?

A)Possible false-positive
B)Possible false-negative
C)Depends on the amount of antibody present in the sample
D)No effect on the results

Answer 1

Possible false-negative

Question 2

In nephelometric methods, the relationship between the protein being assayed (the antigen in this instance) and the concentration of the protein in the sample (as measured by the instrument as the amount of scattered light) is

A)inversely proportional.
B)directly proportional.

Answer 2

directly proportional.

Question 3

The strength of an agglutination reaction can be enhanced by

A)centrifugation.
B)use of albumin.
C)use of low ionic strength saline.
D)All of the above.

Answer 3

All of the above.

Question 4

The definition of the term agglutination is the

A)visible expression of the aggregation of antigens and antibodies.
B)formation of a framework in which antigen particles or molecules alternate with antibody molecules.
C)term used to describe the aggregation of particulate test antigens.
D)All of the above.

Question 5

With agglutination inhibition in pregnancy testing, a negative result is evidenced by

A)agglutination.
B)no agglutination.

Question 6

The most efficient type of antibodies in agglutination reactions are

A)IgM.
B)IgG.
C)IgD.
D)IgE.

Question 7

The first phase of agglutination represents

A)physical attachment of antibody molecules to antigens on the erythrocytic membrane.
B)physical attachment of antigens to antibody molecules on the erythrocytic membrane.
C)a reversible chemical reaction.
D)Both A and C.

Question 8

A fundamental prerequisite for nephelometric protein quantitation is the

A)dissolution of large protein molecules.
B)formation of a macromolecular complex.
C)pH of the solution.
D)ionic strength of the solution.

Question 9

The quality of agglutination or precipitation test results depends on

A)length of incubation with the serum containing antibody.
B)amount of antigen conjugated to the carrier.
C)pH.
D)All of the above.

Question 10

Precipitation is the term applied to

A)the aggregation of soluble test antigens.
B)the aggregation of soluble test antibodies.
C)Either A or B.
D)the aggregation of particulate test antigens.

Question 11

An artificial carrier could be

A)latex particles.
B)colloidal charcoal.
C)erythrocytes coated with antigen.
D)Both A and B.

Question 12

Anti-human globulin (AHG) is used to

A)substitute for a low titer of antibody.
B)alter the configuration of an antigen.
C)form cross-links between antibodies bound to the surface of erythrocytes.
D)form cross-links between antigens bound to the surface of erythrocytes.

Question 13

A false-positive latex agglutination assay for pregnancy can be produced by all the following except:

A)cross-reactivity with luteinizing hormone (LH).
B)cross-reactivity with follicle-stimulating hormone (FSH).
C)antisperm antibodies.
D)monoclonal antibody directed against the beta subunit of hCG.

Question 14

In a group A patient's reverse serum testing, the cells and serum agglutinate because

A)group A antigen is present on the patient's erythrocytes.
B)group A antigen is present in the patient's serum.
C)anti-group A is present in the patient's serum.
D)Both A and C.

Question 15

In nephelometry measurement, if antigen overwhelms the quantity of antibody, the measured signal

A)increases.
B)decreases.
C)remains the same.
D)fluctuates between high and low.

Question 16

In nephelometry measurement, a __________________ method is used.

A)variable-time
B)fixed-time
C)fluorescent-tagging
D)competitive immunoassay

Question 17

The lattice hypothesis states that an optimal reaction occurs between antigen and antibody when

A)an excess of antigen is present.
B)an excess of antibody is present.
C)antigen and antibody are present in approximately equal proportions.
D)reaction takes place at room temperature.

Question 18

Which of the following is a correct statement regarding measurements of turbidity?

A)Light is scattered at a determined angle.
B)It is unaffected by large particles precipitating out of a solution.
C)The reference value is recorded in units of relative light scatter.
D)It represents the scattered light in forward direction.

Question 19

Latex particles act as ______________________ in nephelometry.

A)antigen-coated reaction intensifiers
B)antigen-coated reaction stabilizers of precipitate
C)sensitivity enhancers
D)color reaction intensifiers

Question 20

All the following procedures are typically performed by latex agglutination or latex agglutination inhibition assays except

A)C-reactive protein (CRP).
B)rheumatoid factors (IgG).
C)pregnancy testing.
D)RPR for syphilis.

Question 21

Nephelometry can be used to assay all the following except:

A)IgM.
B)IgG.
C)IgD.
D)IgA.

Question 22

Cryoglobulin analysis can be useful in the diagnosis of

A)hypothermia.
B)Raynaud's phenomenon.
C)infectious hepatitis.
D)rheumatoid arthritis.

Question 23

Match the cause of a false-positive agglutination reaction with the appropriate corrective measure.
Over centrifugation of cells and serum

A)Use a control with saline and no antibody.
B)Read reactions exactly as specified.
C)Calibrate centrifuge to proper speed and time.
D)Use positive and negative QC cells.

Question 24

Match the cause of a false-negative agglutination reaction with the appropriate corrective measure.
Anti-human globulin (AHG) malfunction

A)Dilute patient's serum and retest.
B)Wash cells according to directions; use positive and negative quality control (QC) steps.
C)Repeat blood specimen should be collected a week or more later.
D)Calibrate centrifuge to proper speed and time.

Question 25

Match the term with the appropriate description.
Prozone phenomenon

A)The zone in which optimum precipitation occurs
B)An excessive antibody concentration that produces a false-negative reaction
C)An excessive antigen concentration that results in no lattice formation
D)An equal amount of antigen and antibody concentrations

Question 26

Match the type of immunoglobulin with the optimal thermal range.

-IgG

A)4 to 22 $\degree$ C
B)18 to 22 $\degree$ C
C)37 $\degree$ C
D)56 $\degree$ C

Question 27

Match the cause of a false-negative agglutination reaction with the appropriate corrective measure.
Postzone phenomenon

A)Dilute patient's serum and retest.
B)Wash cells according to directions; use positive and negative quality control (QC) steps.
C)Repeat blood specimen should be collected a week or more later.
D)Calibrate centrifuge to proper speed and time.

Question 28

Cryoglobulins are proteins that precipitate or gel when cooled to

A)-18° C
B)0° C
C)4° C
D)18° C

Question 29

Match the type of immunoglobulin with the optimal thermal range.

-IgM

A)4 to 22 $\degree$ C
B)18 to 22 $\degree$ C
C)37 $\degree$ C
D)56 $\degree$ C

Question 30

Match the following terms with the correct definition.
Coagglutination

A)Uses antibodies bound to a particle to enhance the visibility of the reaction
B)Based on the interaction of soluble antigen with antibody
C)Detects antibodies with erythrocyte antigens

Question 31

Match the term with the appropriate description.
Postzone phenomenon

A)The zone in which optimum precipitation occurs
B)An excessive antibody concentration that produces a false-negative reaction
C)An excessive antigen concentration that results in no lattice formation
D)An equal amount of antigen and antibody concentrations

Question 32

Match the following terms with the correct definition.
Hemagglutination

A)Uses antibodies bound to a particle to enhance the visibility of the reaction
B)Based on the interaction of soluble antigen with antibody
C)Detects antibodies with erythrocyte antigens

Question 33

Monoclonal cryoglobulins are most often

A)IgM.
B)IgG.
C)IgA.
D)Either A or B.

Question 34

Match the cause of a false-positive agglutination reaction with the appropriate corrective measure.
Autoagglutination

A)Use a control with saline and no antibody.
B)Read reactions exactly as specified.
C)Calibrate centrifuge to proper speed and time.
D)Use positive and negative QC cells.

Question 35

Match the cause of a false-negative agglutination reaction with the appropriate corrective measure.
Prozone phenomenon

A)Dilute patient's serum and retest.
B)Wash cells according to directions; use positive and negative quality control (QC) steps.
C)Repeat blood specimen should be collected a week or more later.
D)Calibrate centrifuge to proper speed and time.

Question 36

Match the following terms with the correct definition.
Flocculation

A)Uses antibodies bound to a particle to enhance the visibility of the reaction
B)Based on the interaction of soluble antigen with antibody
C)Detects antibodies with erythrocyte antigens