ACTUAL EXAM 1 SEROLOGY
The accuracy of an immunoassay is its ability to discriminate between results that are true positive and results that are true negative. Two parameters of test accuracy are specificity and sensitivity. Which of these statements apply to an immunoassay with high specificity?
Accurately identifies the absence of disease
Which of the following BEST describes the relation of nephelometry to turbidimetry?
Nephelometry directly measures the amount of light scattered by particles in solution, and turbidimetry measures the decrease in incident-light intensity
The components of the second line of defense against microbes may be characterized as
Phagocytes cells; complement
Which components characterize the second line of human body defense against microbial pathogens?
Phagocytic neutrophils and macrophages
When we ran the serum (antibodies) of a patient who seems to be severely ill with arthritis at the lowest dilution suggested by the latex agglutination kit, the results were negative. What should we do?
Dilute the sample and run it again before the results are reported.
A nasopharyngeal specimen is processed and fixed onto a microscope slide. Next, the fluorescein-conjugated antibody is added to the slide. The specimen is incubated with the labeled antibody, washed, and then observed for fluorescence. Which of the following techniques best describes this process?
Direct immunofluorescence
An immunoassay is performed in the following way: Antigen is bound to a solid support. Patient serum is added, and patient antibodies bind to the antigen. The well is washed, and enzyme-labeled anti-immunoglobulin antibodies are added. The well is washed, and enzyme substrate is added. Enzyme activity is determined. Which immunoassay is described?
ELISA
Indirect immunofluorescence is similar to which type of enzyme immunoassay in terms of the performance of the assay?
ELISA
When a polyclonal gammopathy is compared to a monoclonal gammopathy, a patient with a polyclonal gammopathy has:
Elevated levels of several classes of immunoglobulin molecules.
Which region of the immunoglobulin molecule can bind antigen?
Fab
The properties of an antibody class are defined by the:
Fc end of the molecule
What is the most appropriate laboratory safety wear?
Fluid-resistant laboratory gown with wrist cuffs
What is the process of monoclonal antibody production?
Fusion of antibody specific lymphocyte and myeloma cell
In serum protein electrophoresis, which band contains the immunoglobulins?
Gamma
The probability that a person with a positive screening test actually has the disease screened for is called:
Positive predictive value
The directions for a slide agglutination test instruct that after mixing the patient's serum and latex particles the slide must be rotated for 2 minutes. What happen if the slide were rotated for 10 minutes?
Possible false positive result
Which is characteristic of IgG?
Provides immunity for the newborn
What has happened in an antibody titer, if tubes #5-7 show a stronger reaction than tubes #1-4?
Prozone reaction
The term TITER (as it applies to the measurement of antibodies) is best defined as:
Reciprocal of maximum reactive dilution
Where should you dispose of blood-soaked gauze pads?
Red biohazard bag
What is the best procedure for removing gloves when leaving the laboratory?
Take gloves off and wash hands
In a capture assay to determine the presence of a viral antigen in a patient sample, which of the following would be on solid phase?
Unlabeled antibody
Nephelometry and turbidimetry measure different properties of:
Light transmission and scatter by particles in suspension
A serological test that uses red blood cells coated with exogenous antigens such as bacterial polysaccharides as a method to detect patient antibodies against that exogenous antigen is called:
hemagglutination
Monoclonal antibodies are produced by
hybridomas
skin and mucous membranes are important components of what part of the immune system?
innate immunity
according to the clinical laboratory improvement amendments (CLIA) regulations, which of the following applies to a test that is easy to perform and interpret?
it can be performed by someone who does not have specific training (waived)
The immunoglobulin molecule is made up of both heavy and light chains - the light chains can be comprised of which of the following?
kappa or lambda
Which of the following pairs represents light chains of antibody molecules?
lambda and kappa
Which of the following cells are capable of producing antibodies?
lymphocytes
From the IgG molecule illustration, which region is the heavy chain?
A
What is the proper concentration of sodium hypochlorite needed to disinfect your bench station?
1:10
When should acute and convalescent blood specimens be collected from a patient for the detection of antibody concentration related to a specific infectious disease?
2 weeks apart
Prozone is observed in:
A patient sample in which the serum contains a high titer of antibody
A cytokine can be described as:
A soluble protein that regulates the immune response
What form of immunity is expected to provide long-term protection after hepatitis B vaccine (HBV) is administered to an incompetent person?
Active
For which of the following test is a lack of agglutination a positive reaction?
Agglutination inhibition
antibodies are produced bu:
B cells
Which of the following is responsible for the humoral response:
B lymphocytes
Which of the following choices best describes the primary function of antibodies?
Binds with antigen
All of the following are desirable characteristics of antibodies used in immunoassays except
High cross reactivity
A secondary immune response is generally associated with which of the following antibodies?
IgG
Which immunoglobulin appears in the highest titer in the secondary response?
IgG
Which of the following antibody types is the predominant serum antibody seen in the secondary immune response:
IgG
which antibody class may require the use of an enhancement technique to visualize the reaction?
IgG
what characteristic differentiates a secondary immune response from a primary immune response?
IgG is the predominant antibody class produced in the secondary immune response compared to the primary immune response
A primary immune response is generally associated with which antibody?
IgM
Which class of immunoglobulin possesses 10 antigenic binding sites
IgM
which immunoglobulin appears first in the primary response?
IgM
Point-of-care testing is performed most easily using:
Immunochromatographic assay
What outcome results from improper washing of a tube of well after adding the enzyme-antibody conjugate in an ELISA system?
Result will be falsely increased
A laboratory is evaluating an ELISA assay for detecting an antibody to CCP (antigen) which is a marker for rheumatoid arthritis. The lab includes serum form healthy volunteers and patient with other autoimmune disorders in the evaluation. These specimens determine which factor of the assay?
Specificity
You are performing a manual antibody titer in a clinical laboratory. You have made serial dilutions of a patient's plasma sample and you are looking for anti-streptolysin O antibodies. The first tube contains pure patient plasma. The second tube contains a 1:2 dilution of the first tube. The third tube contains a 1:2 dilution of the second tube and so on. The patient's antibodies no longer give visible reaction in tube 5, indicating their titer is tube 4 (or the last tube where there is a positive result). What is the concentration of antibodies in tube 4 compared to the concentration in tube 1?
The concentration of antibodies in tube 4 is 1/8 the concentration of antibodies in tube 1
A patient has been recently exposed to an inhaled fungus, and it seems likely that an infection is starting. The current approved test for diagnosis is an Ouchterlony test with her antibody sample in a well and several different fungal antigens in wells surrounding it. No precipitin line occurred.
The patient's blood should be drawn again in 2 weeks and retested.
Identify the true statement about the anamnestic response (secondary response) versus the primary response.
The primary response has a long lag phase; the anamnestic response has a short lag phase.
What section of an immunoglobulin molecule is responsible for the differences between immunoglobulin classes?
heavy chains
which is most sensitive?
a heterogeneous labeled immunoassay
The name of a reaction between a single antigenic determinant and an individual combining site is:
affinity
What does the gel in an Ouchterlony contain, and what does the gel in a radial immunodiffusion contains?
agarose only, antibody in agarose
A serological reaction is set up in which the antigen is bound to a large carrier, the antibody is soluble, and they bind and form an insoluble complex that is detected macroscopically. What type of assay is described?
agglutination
which statement about noncompetitive enzyme immunoassays is true?
all patient antigen is allowed to react with binding sites
The Centers for Disease Control and Prevention developed standard precautions using the assumption that:
all patients are potentially infected or carriers of transmittable organisms, so appropriate precautions need to be followed.
In a competitive immunoassay, the
amount of signal is inversely proportional to the amount of patients antibody and can be determined from a standard curve
Which part of a quality management program involves the use of external controls?
analytical
The specificity of an immunoassay is determined by the:
antibody used in the assay
The strength of a visible reaction is known as:
avidity
An immunoassay is performed in the following manner to look for an antigen (Ag) in the patient serum: Patient serum + labeled Ag + known antibody (Ab) are added together and incubated. Unbound material is washed off. The amount of labeled Ag is then measured. What assay is performed?
competitive
the concentration of a solution is reduced by adding:
diluent
A tissue section is fixed to a microscope slide, then incubated with a fluorescently labeled antibody that binds to an antigen expressed by cells in that tissue. The preparation is then washed and inspected with a fluorescent microscope. This technique is called:
direct immunofluorescence
Which test has the greatest sensitivity for antigen detection?
enzyme linked immunosorbent assay-ELISA
Concerning antigen-antibody reactions, the prozone effect causes which of the following results?
false negative
in a standard electrophoretic separation, what zone appears last (travels less towards anode) on the densitometric pattern
gamma globulins
Two biologically functional characteristics of immunoglobin G (IgG) are:
osponization of antigens for phagocytosis by macrophages and neutrophils; neonatal immunity by transfer of maternal antibodies across the placenta and gut of the fetus
When carrier particles are coated with an antigen that is not normally found on them, this is known as:
passive agglutination
A soluble antigen and soluble antibody reacting to form an insoluble product describes
precipitation reactions
Which of the following describes an antigen-antibody precipitation reaction of non-identity?
precipitin lines cross, forming double spurs
the following pattern of agglutination was observed in an antibody titration this set of reactions was most likely resulted from:
prozoning
the first labeled assays developed were
radioimmunoassay
The definition of titer is the
reciprocal of the last positive dilution
What does the acronym RACE stand for?
rescue, alarm, contain, extinguish
Blood is drawn from a patient for serological tests for a viral disease at the time of onset and again 4 weeks later. The results of the test are considered diagnostic if the:
second antibody titer is at least 4x the first
avidity is best described by which of the following statements?
the strength with which multivalent antigens and antibodies bind
All of the following would be considered a part of the body's cellular immune system EXCEPT?
thrombocytes