Deck 9: Overview of Immunochemical Methods Used for Organism Detection

Question 1

Neutralizing antibodies are those that function by:

A)attaching to the surface of pathogens and contributing to their destruction by the lytic action of complement.
B)binding to and blocking surface receptors for host cells.
C)attaching to the surface of pathogens and making the pathogens more amenable to ingestion by phagocytic cells.
D)attaching to the surface of pathogens and contributing to their destruction by chemotaxis.

Answer 1

B
Antibodies function in different ways.Neutralizing antibodies work by binding to and blocking surface receptors for host cells.

Question 2

A test procedure that applies a specific fluorescent dye-antibody complex to a slide to which the patient specimen has been applied is referred to as a(n):

A)solid-phase enzyme immunoassay.
B)direct fluorescent antibody test.
C)indirect fluorescent antibody test.
D)radioimmunoassay.

Answer 2

B
The direct fluorescent antibody test applies an antibody-fluorescent dye complex directly to the specimen.

Question 3

The precipitin test that involves antigen and antibody diffusing toward each other,producing a visible precipitin band at the point at which they meet,is referred to as:

A)double immunodiffusion.
B)counterimmunoelectrophoresis.
C)particle agglutination.
D)enzyme immunoassay.

Answer 3

A
Double immunodiffusion is a test that involves an antigen and antibody diffusing toward each other to produce a precipitin band at the meeting point.

Question 4

The difference between latex agglutination and coagglutination is:

A)the type of particle used to carry the antibody.
B)the type of target organism involved.
C)that coagglutination is less specific but more sensitive.
D)that coagglutination,not latex agglutination,can be used for direct antigen detection.

Question 5

A sample suspected of containing Legionella pneumophila is treated with the dye fluorescein isothiocyanate (FITC);however,the sample fluoresced a bright apple-green colony after it was processed.Which of the following statements explains this discrepancy?

A)A technical error may have occurred.
B)The fluorescent bulb may have malfunctioned.
C)The results are accurate;no discrepancy is found.
D)A postanalytical error is to blame.

Question 6

Antibody-mediated immune responses produced by specific proteins are generated by:

A)lymphocytes of the T class.
B)lymphocytes of the B class.
C)neutrophils.
D)basophils.

Question 7

Opsonizing antibodies are those that function by:

A)attaching to the surface of pathogens and contributing to their destruction by the lytic action of complement.
B)binding to and blocking surface receptors for host cells.
C)attaching to the surface of pathogens and making the pathogens more amenable to ingestion by phagocytic cells.
D)attaching to the surface of pathogens and contributing to their destruction by chemotaxis.

Question 8

Elevations of which of the following antibodies may indicate a parasitic infection?

A)IgG
B)IgA
C)IgM
D)IgE

Question 9

For an accurate diagnostic of a current infection,acute and convalescent sera should reflect a(n)_____ in the patient's antibody titer of _____ doubling dilutions.

A)decrease;two
B)increase;two
C)decrease;four
D)increase;four

Question 10

The major advantage of immunofluorescent microscopy assays is that:

A)extensive training is not necessary.
B)it serves as an excellent way to preserve the reaction for referral and archiving.
C)visual assessment of the adequacy of a specimen is possible.
D)fluorescent microscopes are easily accessible to most laboratories.

Question 11

The study of the diagnosis of disease by measuring antibody levels in serum is called:

A)immunology.
B)immunohematology.
C)serology.
D)immunocytology.

Question 12

For most pathogens to be diagnostic of current infection,there must be a(n)_____ in the patient's antibody titer of _____ doubling dilutions.

A)decrease;two
B)increase;two
C)decrease;four
D)increase;four

Question 13

The presence of which of the following antibodies usually indicates a recent or an active infection?

A)Immunoglobulin (Ig)G
B)IgA
C)IgM
D)IgE

Question 14

Cell-mediated immune responses,such as attacking and killing microorganisms or host cells that are damaged or infected,are carried out by:

A)lymphocytes of the thymus-derived (T)class.
B)lymphocytes of the bone marrow-derived (B)class.
C)neutrophils.
D)nasophils.

Question 15

The antibody that is predominantly found in tears,saliva,and intestinal secretions is:

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

Question 16

Complement-fixing antibodies are those that function by:

A)attaching to the surface of pathogens and contributing to their destruction by the lytic action of complement.
B)binding to and blocking surface receptors for host cells.
C)attaching to the surface of pathogens and making the pathogens more amenable to ingestion by phagocytic cells.
D)attaching to the surface of pathogens and contributing to their destruction by chemotaxis.

Question 17

Polyclonal antibodies are those that:

A)react with many different types of antigens.
B)react with many species of bacteria within the same genus.
C)react with many different antigens of one specific organism.
D)can be produced from many different species of host organisms.

Question 18

Monoclonal antibodies are those that:

A)react with many different types of antigens.
B)react with many species of bacteria within the same genus.
C)are produced by the offspring of a single hybrid cell.
D)can be produced from many different species of host organisms.

Question 19

The precipitin test that is widely used for detecting antibodies against fungal infection is referred to as:

A)double immunodiffusion.
B)counterimmunoelectrophoresis.
C)particle agglutination.
D)enzyme immunoassay.

Question 20

A positive latex agglutination test was observed in a sample containing Cryptococcus neoformans.The specimen of choice to identify this pathogen is:

A)urine.
B)blood.
C)stool.
D)cerebrospinal fluid (CSF).

Question 21

The immunochemical test that involves the agglutination of an artificial carrier particle with the antigen bound to its surface and an antibody present in a specimen is referred to as:

A)double immunodiffusion.
B)counterimmunoelectrophoresis.
C)particle agglutination.
D)enzyme immunoassay.

Question 22

A positive test was observed on a serum sample that resulted in the formation of a fine precipitate on a reaction card.The most likely organism serologically identified is:

A)Chlamydia trachomatis.
B)Bacillus anthracis.
C)Treponema pallidum.
D)Toxoplasma gondii.

Question 23

A Western blot assay was performed,and bands were observed at p24,p41,and gp120/160 (kilodaltons).The organism can be identified as:

A)herpes simplex virus.
B)human immunodeficiency virus (HIV).
C)Borrelia burgdorferi.
D)T.pallidum.

Question 24

A patient was suspected of having a rickettsial infection after hiking in the Rocky Mountains.A Weil-Felix test was performed,which resulted in no agglutination observed.Which one of the following statements explains this discrepancy?

A)Detection of rickettsial infections using strains of Proteus is not as specific as other serologic tests;therefore the infections should be retested with a newer method.
B)The Weil-Felix test is not the appropriate test to order;it cannot detect cross-reacting antibodies.
C)Rickettsial antibodies should be tested using the fluorescent treponemal antibody absorption (FTA-ABS)test,not the Weil-Felix test.
D)No discrepancy is present.Rickettsial antibodies do not agglutinate with Proteus antigens.

Question 25

The difference between latex agglutination and hemagglutination is:

A)the type of particle used to carry the antibody.
B)the type of target organism involved.
C)that hemagglutination is less specific but more sensitive.
D)that hemagglutination procedures are temperature sensitive.

Question 26

A pregnant woman had contact with her nephew who was just diagnosed with a rubella infection.Acute and convalescent samples were taken,which resulted in an acute titer of 1:16 and a convalescent titer of 1:32.Which one of the following comments explains the risk to the fetus?

A)The risk is low;a fourfold rise in titer is not present.
B)The risk is high;more than a fourfold rise is present in titer.
C)The risk is high because both titers are elevated.
D)Rubella is not a congenital disease;therefore the test should not have been ordered.

Question 27

Specific proteins produced by cells of the immune system in response to the presence of foreign molecules that circulate in the serum and are present in secretions such as saliva are called:

A)antigens.
B)immunoglobulins.
C)cytokines.
D)phagogens.