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Medical Laboratory Science Review: Immunology
Terms in this set (165)
Identify a specific component of the adaptive immune system that is formed in response to antigenic stimulation:
Which two organs are considered the primary lymphoid organs in which immunocompetent cells originate and mature?
Thymus and bone marrow
T cells travel from the bone marrow to the thymus for maturation. What is the correct order of the maturation sequence for T cells in the thymus?
Bone marrow to the cortex; after thymic education, released back to the peripheral circulation
What type of B cells are formed after antigen stimulation?
Mature B Cells
Which cluster of differentiation (CD) marker appears during the first stage of T-cell development and remains present as an identifying marker for T cells?
Which markers are found on mature, peripheral helper T cells?
Which T cell expresses the CD8 marker and acts specifically to kill tumors or virally infected cells?
How are cytotoxic T cells and natural killer cells similar?
Effective against virally infected cells
Wht is the name of the process by which phagocytic cells are attracted to a substance such as a bacterial peptide?
All of the following are immunologic functions of complement except:
Induction of an antiviral state
Induction of an antiviral state
Which complement component is found in both the classic and alternative pathways?
Which immunoglobulins help initiate the classic complement pathway?
IgG and IgM
How is complement activity destroyed in vitro?
Heating serum at 56 degrees C for 30 min
What is the purpose of C3a, C4a, and C5a, the split products of the complement cascade?
The cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils.
Which region of the immunoglobulin molecule can bind antigen?
Which region determines whether an immunoglobulin molecule can fix complement?>
Which immunoglobulin classes have a J chain?
IgM and sIgA
Which immunoglobulin appears first in the primary immune response?
Which immunoglobulin appears in highest titer in the secondary response?
Which immunoglobulin can cross the placenta?
Which immunoglobulin cross links mast cells to release histamine?
All of the following are functions of immunoglobulins except:
Neutralizing toxic substances
Facilitating phagocytosis through opsonization
Interacting with Tc cells to lyse viruses
combining with complement to destroy cellular agents
Interacting with Tc cells to lyse viruses
Which of the cell surface molecules is classified as an MHC class II antigen?
Which MHC class of molecule is necessary for antigen recognition by CD4-positive T cells?
Which are products of HLA class II genes?
Complement proteins C2, C4, and Factor B
What molecule on the surface of most T cells recognizes antigen?
TcR consisting of two chains, alpha and beta
The T-cell antigen receptor is similar to immunoglobulin molecules in that it
Contains V and C regions on each of its chains
Toll-like receptors are found on which cells?
Macrophages produce which of the following proteins during antigen processing?
IL-1 and IL-6
A superantigen, such as toxic shock syndrome toxin-1, bypasses the normal antigen processing stage by binding to and crosslinking
A portion of a t-cell receptor and an MHC class II molecule
T regulator cells, responsible for controlling autoimmune antibody production, express which of the following phenotypes?
CD3, CD4, CD25
The interaction between an individual antigen and antibody molecule depends upon several types of bonds such as ionic bonds, hydrogen bonds, hydrophobic bonds, van der Waals forces. How is the strength of this attraction characterized?
A lab is evaluating ELISA for detecting an antibody to cyclic citrullinated peptide (CCP), which is a marker for rheumatoid arthritis. The laboratory includes serum from healthy volunteers and patients with other connective tissue diseases in the evaluation. These specimens determine which factor of the assay?
Which part of the radial immunodiffusion (RID) test system contains the antisera?
What is the interpretation when an Ouchterlony plate shoes crossed lines between wells 1 and 2 (antigen is placed in the center well and antisera in wells 1 and 2)
Nonidentity between wells 1 and 2
WHy is chemiluminescent immunoassay or enzyme immunoassay the method of choice for detection of certain analytes, such as hormones, normally found in low concentrations?
Because of high sensitivity
What comprises the indicator system in an indirect ELISA for detecting antibody?
Enzyme-conjugated antibody + chromogenic substrate
What outcome results from improper washing of a tube or well after adding the enzyme-antibody conjugate in an ELISA system>?
Result will be falsely increased
What would appen if the color reaction phase is prolonged in one tube or well of an ELISA test?
Result will be falsely increased
The absorbance of a sample measured by ELISA is greater than the highest standard. What corrective action should be taken?
Dilute the test sample
A patient was suspected of having a lymphoproliferative disorder. After several laboratory tests were completed, the patient was found to have an IgMk paraprotein. In what sequence should the laboratory tests leading to this diagnosis have been performed?
Serum protein electrophoresis followed by immunofixation electrophoresis
An IFE (immunofixation electrophoresis) performed on a serum showed a narrow dark band in the lanes containing anti-gamma and anti-lambda. How should this result be interpreted?
Abnormal test result demonstrating monoclonal IgG Lambda
Which type of nephelometry is used to measure immune complex formation almost immediately after reagent has been added?
An immunofluorescence microscopy assay (IFA) was performed, and a significant antibody titer was reported. Positive and negative controls performed as expected. However, the clinical evaluation of the patient was not consistent with a positive finding. What is the most likely explanation of this situation?
The pattern of fluorescence was misinterpreted
What corrective action should be taken when an indeterminate pattern occurs in an indirect IFA?
Dilute the sample and retest
Which statement best describes passive agglutination reactions used for serodiagnosis?
Carrier particles for antigen such as latex particles are used
What has happened in a titer, if a tube Nos. 5-7 show a stronger reaction than tube Nos. 1-4?
What is the titer in tube No. 8 if tube No. 1 is undiluted and dilutions are doubled?
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 would happen if the slide were rotated for 10 minutes
Possible false negative result
What effect does selecting the wrong gate have on the results when cells are counted by flow cytometry?
Failure to count the desired cell population
Which statement best describes immunophenotyping?
Lineage determination by detecting antigens on the surface of the gated cells using fluorescent antibodies
A flow cytometry scattergram of a bone marrow sample shows a dense population of cells located inbetween normal lymphoid and normal myeloid cells. What is the most likely explanation?
An abnormal cell population is present
Which serum antibody response usually characterizes the primary stage of syphilis?
Detected 1-3 weeks after appearance of primary chancre
What substance is detected by rapid plasma reagin (RPR) and Venereal Disease Research Laboratory (VDRL) tests for syphilis?
What type of antigen is used in the RPR card test?
Which is the most sensitive test to detect congenital syphilis
A biological false-positive reaction is least likely which test for syphilis?
fluorescent T. Pallidum antibody absorption test (FTA-ABS)
A 12 year old girl has symptoms of fatigue and a localized lymphadenopathy. Lab tests reveal a peripheral blood lymphocytosis, a positive RPR, and a positive spot test for IM. What test should be performed next?
Treponema pallidum particle agglutination (TP-PA) test
Which test is most likely to be positive in the tertiary stage of syphilis?
What is the most likely interpretation of the following syhilis serological results?
reactive; VDRL- Reactive
Biological false positive
Which specimen is the sample of choice to evaluate latent or tertiary syphilis?
Interpret the following quantitative RPR test results:
RPR titer: weakly reactive 1:8; reactive 1:8-1:64
Excess antibody, prozone effect
Tests to identify infection with HIV fall into which three general classification types of tests?
Tests for antigens, antibodies, and nucleic acid
Which tests are considered screening tests for HIV?
ELISA, 4th generation, and rapid antibody tests
Which tests are considered confirmatory tests for HIV?
Western Blot test, HIC-1,2 differentiation assays, and polymerase chain reaction
Which is most likely a positive Western Blot result for infection with HIV?
bands at p24 and gp120
A woman who has had five pregnancies subsequently tests positive for HIV by Western blot. What is the most likely reason for this result?
Cross-reaction with HLA antigens in the antigen preparation.
HIV 1,2 ELISA: Pos
Western Blot: indeterminate
HIV-1 p24 antigen: neg
Additional testing required
What is the most likely explanation when antibody tests for HIV are negative but a PCR test performed 1 week later is positive?
Patient is in the window phase before antibody production
What criteria constitute the classification system for HIV infection?
CD4-positive T-cell count and clinical symptoms
What is the main difficulty associated with the development of an HIV vaccine?
Different strains of the virus are genetically diverse
Which CD4:CD8 ratio is most likely in a patient with AIDS?
What is the advantage of 4th generation rapid HIV tests?
They detect p24 antigen
Which method is used to test for HIV infection in infants who are born to HIV-positive mothers?
What is the most likely cause when a western blot or ELISA is positive for all controls and samples?
What constitutes a diagnosis of viral hepatitis?
Abnormal test results for liver enzymes
Clinical signs and symptoms
positive results for hepatitis markers
Which of the statements regarding infection with hepatitis D virus is true?
Occurs in patients with hepatitis B
All of the following hepatitis viruses are spread through blood or blood products except
Which hepatitis B marker is the best indicator of early acute infection?
Which is the first antibody detected in serum after infection with hepatitis B virus?
Which antibody persists in low-level carriers of hepatitis B virus?
What is the most likely explanation when a patient has clinical signs of viral hepatitis but tests negative for hepatitis A IgM, hepatitis B surface antigen, and hepatitis C Ab?
The patient may be in the core window
Which hepatitis B markers should be performed on blood products?
HBsAG and anti-HBc
Which hepatitis andtibody confers immunity against reinfection with hepatitis B viruse?
Which test, other than serological markers, is most consistently elevated in viral hepatitis?
Alanine aminotransferase (ALT)
If only anti-HBs is positive, which of the following can be ruled out?
Chronic hepatitis B virus infection
Interpret the results for EBV infection: IgG and IgM antibodies to viral capsid antigen (VCA) are positive.
Which statement concerning non-forssman heterophile antibody is true?
It is not absorbed by guinea pig antigen
Given a heterophile antibody titer of 224, which of the following results indicate IM?
Two tube titer reduction in GP kidney, Five-tube titer reduction with beef cells
Given a heterophile antibody titer of 224, which of the following results indicate serum sickness?
Five-tube titer reduction GP kidney, five-tube titer reduction in beef cells
Given a heterophile antibody titer of 224, which of the following results indicate an error in testing?
No titer reduction in GP kidney, no titer reduction in beef cells
Blood products are tested for which virus before being transfused to newborns?
What is the endpoint for the antistreptolysin O (ASO) latex agglutination assay?
Highest serum dilution that shows agglutination
Interpret the following antistreptolysin O latext agglutination results:
Tubes 1-4 (todd unit 125): no hemolysis; Tube 5: hemolysis
Positive Todd unit 125
Which control shows the correct result for a valid ASO test?
Red cell control, no hemolysis
A streptozyme test was performed, but the result was negative, even though the patient showed clinical signs of streptococcal throat infection. What should be done next?
Either ASO or anti-deoxyribonuclease B testing
Rapid assays fro influenza that utilize specimens obtained from nasopharyngeal swabs detect
How can interfering cold agglutinins be removed from a test sample?
Incubate the clot at 1-4 degrees for several hours, then remove serum
All tubes (dilutions) excepts the negative control are positive for cold agglutinins. This indicates:
Further serial dilution is necessary
All positive cold agglutinin tubes remain positive after 37 degrees incubation except the positive control. What is the most likely explanation for this situation?
Antibody other than cold agglutinins
Which increase in antibody titer (dilution) best indicates an acute infection
From 1:16 to 1:256
Which of the following positive antibody tests may be an indication of recent vaccination or early primary infection for rubella in a patient with no clinical symptoms?
Only IgM antibodies positive
Why is lab diagnosis difficult in cases of Lyme disease/
Clinical response may not be apparent upon initial infection; IgM antibody may no be detected until 3-6 weeks after infection
Serological tests for which disease may give a false-positive result if the patient had Lyme disease?
In monitoring an HIV-infected patient, which parameter may be expected to be the most sensitive indicator of the effectiveness of antiretroviral treatment?
HIV viral load
A renal transplant recipient is found to have a rising creatinine level and reduced urine output. this physician orders a urine CR assay. When you call to find out what organism the physician wants to identify, you are told
A newborn is to be tested for a vertically transmitted HIV infection. Which of the following tests is most useful?
Which method is used for HIV identification and considered a signal amplification technique?
branched chain DNA analysis
Which fungal organisms is best diagnosed by an anitbody detection test as opposed to an antibody detection assay?
Your cytology lab refers a Papanicolau smear specimen to you for an assay designed to detect the presence of a virus associated with cervical cancer, you perform?
A molecular assay for HPV
An immunocompromised patient has an unexplained anemia. The physician suspects a parvovirus B19 infection. A parvovirus IgM test is negative. The next course of action is to tell the physician:
A parvovirus PCR is recommended
what is a general definition for autoimmunity?
Loss of tolerance to self-antigens
An antinuclear antibody test is performed on a specimen from a 55 year old woman who has unexplained joint pain. The IFA result is a titer of 40 and a homogeneous pattern. the appropriate follow-up for this patient is:
Retest ANA in 3-6 months
Which disease is likely to show a rim pattern in an immunofluorescence microscopy?
Systemic lupus erythematosus
A patients specimen is strongly positive is an ANA ELISA. Which of the following would not be an appropriate follow u to this result?
Rheumatoid factor assay
What type of antibodies is represented by the solid or homogeneous pattern in the immunofluorescence test for antinuclear antibodies?
What disease is indicated by a high titer of anti-Sm (anti-Smith) antibody?
Which disease is least likely when a nucleolar pattern occurs in an immunofluorescence test for antibuclear antibodies?
What antibodies are represented by the nucleolar pattern in the immunofluorescence test for antinuclear antibodies?
Which test would best distinguished between SLE and MCTD?
Multiplex or ELISA test for anti-SM and Anti RNP
An ANA test on HEp-2 cells shows nucleolar ataining in interphase cells and dense chromatin staining in mitotic cells. the most likely cause of this staining pattern is
Which immunofluorescence pattern indicates the need for ENA testing by Ouchterlony immunodiffusion, Multiplex, or ELISA assays?
Which is used in rapid slide tests for detection of rheumatoid factors?
Fc portion of the IgG molecule
Which of the methods is least likely to give a definitive result for the diagnosis of RA?
Immunofluorescence testing for antinuclear antibodies
Which disease might be indicated by antibodies to smooth muscle?
Antibodies to thyroid peroxidase can be detected by using agglutination assays. Which of the following diseases may show positive results with this type of assay?
Graves disease and Hashimoto's disease
What is the main use of laboratory tests to detect antibodies to islet cells and insulin in cases of insulin-dependent diabetes mellitus (IDDM)?
To screen susceptible individuals prior to destruction of beta cells
A patient present with clinical symptoms of celiac disease. Tests for anti-tissue transglutaminase and antigliadin antibodies are negative. Which of the following tests should be ordered?
HLA DQ typing
Which of the following is a description of a type I hypersensitivity reaction?
Ragweed antigen cross links with IgE on the surface of mast cells, causing release of preformed mediators and resulting in symptoms of an allergic reaction
Why is skin testing the most widely used method to test for a type I hypersensitivity reaction?
Is has greater sensitivity than in vitro measurements
Which in vitro test measures IgE levels against a specific allergen?
Fluorescent allergosorbent test (FAST)
A patient who is blood group O is accidentally transfused with group A blood and develops a reaction during the transfusion. What antibody is involved in this type II reaction?
Which test would measure the coating of red cells by antibody as occurs in hemolytic trasfusion reactions?
Direct antiglobin test
Which test detects antibodies that have attached to tissues, resulting in a type-II cytotoxic reaction?
Which of the conditions will most likely result in a false-negative DAT test?
Insuffiecient washing of the RBCs
Which test is used to detect circulation immune complexes in the serum of some patients with systemic autoimmune diseases such as RA?
Assay of cryoglobulins
Which test would be normal in a type III immune complex reaction
What immune elements are involved in a positive skin test for tuberculosis?
T cells and macrophages
A patient receives a transfusion of packed cells and fresh frozen plasma and develops an anaphylactic, nonhemolytic reaction. She reports receiving a transfusion 20 years earlier. She had no reaction to the previous transfusion, but she did feel poorly a few weeks later. Which of the following transfused substances most likely elicited the reaction?
A patient deficient in the C3 complememtn component would be expected to mount a normal
Type I and type IV hypersensitivity response
Which of the symptoms in a young child may indicate an immunodeficiency syndrome?
Recurrent bacterial, fungal, and viral infections
What screening test should be performed first in a young patient suspected of having an immune dysfunction disorder?
CBC with diff
Which test should be performed when a patient has a reaction to transfused plasma products?
What is the M component in monoclonal gammopathies
Monoclonal antibody or cell line
A child suspected of having an inherited humoral immunodeficiency disease is given diphtheria/tetanus vaccine. Two weeks after, his level of antibody to the specific antigens is measure. Which result is expected for this patient if she indeed has a humoral deficiency?
No change in the level of specific antibody
Which disease may be expected to show IgM spike on an electrophoretic pattern?
In testing for DiGeorge's syndrome, what type of laboratory analysis would be most helpful in determining the number of mature T cells?
interpret the following description of an immunofixation electrohoresis assay of urine. Dense wide bands in both the kappa and lambda lines. No bands present in the heavy chains lanes.
Increased polyclonal Fab fragments
Free monoclonal light chains are often present in the serum of multiple myeloma patients, and may be useful for disease monitoring. Which of the following assays would be recommended to detect the presence of serum-free light chains?
What is measured in the CH50 assay?
Complement needed to lyse 50% of RBCs sensitized RBCs
What type of disorders would show a decrease in C3, C4, and CH50?
Autoimmune disorders such as SLE and RA
What test does not measure phagocyte function?
A patient had surgery for colorectal cancer, after which he received chemotherapy for 6 months. The test for carcinoembryonic antigen (CEA) was normal at this time. One year later, the bimonthly CEA was elevated (>10). An examination and biopsy revealed the recurrence of a small tumor. What was the value of the results rovided y the CEA test in this clinical situation?
Information for further treatment
A carbohydrate antigen 125 assay (CA-125) was performed on a woman with ovarian cancer. After treatment, the levels fell significantly. An examination performed later revealed the recurrence of the tumor, but the CA 125 levels remained low. How can this finding be explained?
CA 125 may not be sensitive enough when used alone to monitor tumor development
What is the correct procedure upon receipt of a test request for human chorionic gonadotropin (hCG) on the serum from a 60 year old man?
Perform the test; hCG may be increased in testicular tumors
Would an hCG test using a monoclonal antibody against the beta-subunit of hCG likely be affected by an increased level of follicle-stimulating hormone?
No, the test would be specific for the beta-subunit of hCG
Which substances, sometimes used as a tumor marker, is increased two- or threefold in normal pregnancy?
Alkaline phosphatase (ALP)
What is the advantage of performing a prostate-specific antigen (PSA) test for prostate cancer?
PSA is stable in serum and not affected by a digital-rectal examination
Which method is the most sensitive for quantitation of AFP?
How is HLA typing used in the investigation of genetic diseases?
For genetic linkage studies
Select the best donor for a man, blood type AB, in need of a kidney transplant
His brother, type AB, HLA matched for class II antigens
A9 and B12 cells damaged; A1 and Aw19 cells intact
Negative for A1 and Aw18; positive for A9 and B12
Which method, classically used for HLA-D typing, is often used to determine the compatibility between a living organ donor and recipient?
Mixed lymphocyte culture (MLC)
Cells type negative for all HLA antigens in a complement-dependent cytotoxicity assay. What is the most likely cause?
Rabbit complement is inactivated
What method may be used for tissue typing instead of serological HLA typing?
PCR, Southern blotting, RFLP
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