Medialab Immunology Questions for MLS ASCP

The assay which is most helpful in identifying specific allergens is: Complement fixation C-reactive proteins RIA RAST

D RAST tests, or Radioallergosorbent tests, are used to screen for an allergy to a specific substance or substances if a person presents with allergy-like symptoms.

Which of the following mediators is released during T-cell activation? immunoglobulins thymosin serotonin lymphokines cytoplasmic granules

D T cells secrete lymphokines, which encourage cell growth, promote cell activation, direct cellular traffic, destroy target cells, and initiate macrophages.

A kidney graft would have the BEST chance of survival post-transplantation if it were: A. HLA non-identical, mixed lymphocyte culture (+), ABO identical. B. HLA identical, mixed lymphocyte culture (+), ABO identical. C. HLA identical, mixed lymphocyte culture (-), ABO identical. D. HLA identical, mixed lymphocyte culture (-), ABO non-identical.

C A graft which is matched based on HLA and ABO typing is ideal. The mixed lymphocyte culture, or MLC, should be negative also to prevent graft vs. host disease in transplant procedures.

Given the following results, what is the immune status of the patient? HbsAg - neg HbeAg - neg Anti-Hbc - neg anti-HBs - pos anti-HBe - neg acute infection chronic infection immunization susceptible

C Anti-HBs is expected to be positive post-vaccination. Since there are no other antigens or corresponding antibodies present in the patient sample, it is likely that patient has been immunized to hepatitis B and is no longer susceptible.

The part of the molecule responsible for differences among immunoglobulin classes is: Fc Fab Heavy chains Light chains

C Antibodies are differentiated based on their heavy chains; different heavy chains create different isotypes. Humans have five different isotypes of immunoglobulins.

The most common rapid slide test (MONOSPOT©) for infectious mononucleosis employs: Horse erythrocytes Sheep erythrocytes Intact beef erythrocytes None of the above

A A positive spot test shows agglutination of horse erythrocytes when added to patient serum previously absorbed with guinea pig kidney, but not when added to patient serum previously absorbed with beef erythrocyte stroma. The test is generally simple, sensitive, and specific, but false negative are common in young children with mononucleosis

All of the following are considered benefits of automated isolation and extraction equipment EXCEPT: Automated isolation equipment is cheaper and more practical Automated isolation equipment requires less manipulation Automated isolation equipment is considered moderate complexity Automated isolation equipment provides consistent results

A Though automated extraction machines have many benefits over manual methods the costs are high and generally require a high throughput of samples in order to justify the costs. Automated extraction has many benefits over the traditional manual methods. The most important benefit is that the nucleic acid isolated is constantly consistent. There is a reduced amount of manipulation with dramatically decreases the chance of cross contamination. Also, automated extraction machines are considered moderate complexity and can be performed by a wider variety of laboratory professionals.

Patient 1234 has a positive antinuclear antibody (ANA) test with a centromere pattern at a 1:1280 titer. Surprised by the result, the clinician calls and says the patient is only having mild stiffness of her fingers and asks your opinion of the result. Which is your best reply? A. You point out that centromere antibodies have been known to occur years prior to the onset of the disease and the patient should be carefully examined and monitored for the development of other symptoms. B. You comment that it's common to over-read ANA results and since the ANA testing is not diagnostic and prone to false results it's unlikely the results are of any concern. C. You state that the ANA results alone are diagnostic of systemic sclerosis and since there is no cure for this disease the clinician is powerless to do anything.

A Centromere antibodies can precede the diagnosis by 10 to 15 years. While the ANA alone is not diagnostic this patient is having clinical symptoms of stiff fingers that fits nicely with the centromere ANA pattern. Early diagnosis and early treatment are important to improve quality of life for the patient.

Which of the following diseases is NOT associated with autoantibodies? Wegener's granulomatosis Rheumatoid arthritis Lupus erythematosus Hemolytic disease of the newborn

A HDN is associated with alloantibodies from the mother's bloodstream directed against the baby's red cell antigens. An infant is not capable of producing his/her own antibodies until 6 months of age. Systemic lupus erythematosus (SLE), Rheumatoid artheritis, and Wegener's granulomatosis are all systemic autoimmune diseases.

Given the following results, what is the immune status of the patient? HbsAg: positive HbeAg: positive Anti-HBc IgM: positive Anti-HBs: negative acute infection chronic infection immunization susceptible

A HbsAg is positive in acute and chronic Hepatitis B infections, since the antigen is found on the actual surface of the virus. HbeAg is present in the blood when the hepatitis B viruses are replicating, indicating an active infection. Anti-Hbc IgM is present due to the immune response to the presence of the hepatitis core antigen and indicates an acute infection. Anti-HBs is generally interpreted as indicating recovery and immunity from hepatitis B virus infection, according to the CDC.

Which of the following antibody types is chiefly seen in the secondary immune response: IgG IgA IgM IgD

A In primary responses, the major class of antibody produced is IgM whereas in the secondary response, as mentioned in this question, it is IgG. IgG is present in the highest quantities compared to all other antibody classes and is the only antibody able to cross the placental barrier.

During which stage in real-time PCR can the fluorescent signal start to be recorded? A. Plateau stage B. Exponential stage C. Leveling stage

A In real-time PCR the fluorescent signal is generally too low to detect until after the first couple of cycles. However, detection usually occurs before the end of the exponential stage.

The cytokine most important for increased macrophage cell activity is: Interferon gamma Interleukin 3 Interleukin 4 Interleukin 5

A Interferon gamma serves various purposes in immunologic response, including being the most potent activator of macrophages by boosting their tumoricidal activity, creating "super" macrophages.

A decrease in which of the following in AIDS patients results in increased susceptibility to infection: CD 4+ cells CD 8+ cells HIV antibodies HIV antigens

A It is the CD 4+ cells that help aid our immune system in attacking foreign antigens by initiating the body's response. CD 8+ also help in the role of immunity by attaching to infected cells to initiate cell destruction. A decrease in HIV antibodies would not leave the host more suseptible to infection since the antibody is directed at the HIV virus only. Finally, a decrease in HIV antigens will also not cause a host to become more suseptible to infections.

The rheumatoid factor in rheumatoid arthritis is PRIMARILY which type of immunoglobulin? IgM IgA IgG IgE

A Rheumatoid Factor (RF) is an antibody against the Fc portion of IgG molecules. It is primarily, of the IgM class and can less commonly be IgG or IgA. These circulating antibody complexes are found in the synovial tissue and synovial fluid and tend to cause systemic problems. In the laboratory, routine latex agglutination test would typically detect only IgM RF since most IgG and IgA antibodies are non-agglutinating.

Which part of the immunoglobulin molecule is responsible for activating complement? Fc Fab heavy chains light chains Hinge regions

A The Fc portion of immunoglobulin can activate the classical complement pathway, where the heavy chains, light chains, hinge regions and Fab portions cannot.

Which of the following would you expect to find in the serum of a patient who has recovered from Hepatitis B infection within 6 months after infection? Anti-HBs HBsAg HBe HCVAb

A The anti-Hbs antibody is produced in response to HBV surface antigen. The anti-Hbs levels in the blood of patient who are infected with hepatitis B will rise during the recovery phase. This test in the laboratory is used to detect previous exposure to HBV, but can also be used to detect successful vaccination. This test is performed mainly to determine whether or not vaccination is necessary or to determine if a person has recovered from a hepatitis B infection and is immune.

Which antibody class is best described with that characteristic that it is the only one capable of residing in mucosal linings? IgA IgM IgG IgE

A The five, distinctive heavy-chain molecules distinguish the antibody class, of isotype. Each heavy chain imparts characteristic features, which permit them to have unique biological functions. IgA, which possesses alpha heavy chains, is the only antibody class capable of residing in mucosal linings. Both IgM and IgG can activate complement. IgM is the largest immunoglobulin, as it is a pentamer. IgG immunoglobulins have the ability to cross the placental barrier. Finally, immediate hypersensitivity reactions are associated with IgE immunoglobulins.

The reaction that occurs when a soluble antigen is mixed with its specific antibody is termed: Precipitation Agglutination Sensitization Fixation

A The reaction that occurs when a soluble antigen is mixed with its specific antibody is termed precipitation. The visible precipitate is composed of large aggregates of antigen crosslinked by antibodies.

Which of the following are useful serological tests to document antecedent Streptococcal infections: ASO anti-DNAse M-antigen Hemolysin

A and B ASO (antistreptolysin O titer) and DNAse (antideoxyribonuclease-B titer) are tests that can be used to detect antecedent streptococcal infections. The ASO is usually utilized to determine whether a previous group A Streptococcus infection has caused a poststreptococcal disease, such as rheumatic fever, scarlet fever, or glomerulonephritis. The anti-DNase test is utilized to determine whether a previous infection of group A beta-hemolytic Streptococcus has occured.

Which of the following factors may increase the likelihood of developing an autoimmune disease? (Choose all that apply) Genetic predisposition Exposure to a triggering event Low birth weight Gender

A, B, and D Genetic predisposition may make some individuals more susceptible to development of an autoimmune disease. An event that triggers the body to perceive antigens as foreign may also lead to the development of an autoimmune disease. Another factor is gender; women are more likely to develop an autoimmune disease. There is no evidence that low birth weight would lead to development of an autoimmune disorder.

Given the following results, what is the immune status of the patient? HbsAg: positive HbeAg: positive Anti-HBc IgM: positive Anti-HBs: negative A. acute infection B. chronic infection C. immunization D. susceptible

A; HbsAg is positive in acute and chronic Hepatitis B infections, since the antigen is found on the actual surface of the virus. HbeAg is present in the blood when the hepatitis B viruses are replicating, indicating an active infection. Anti-Hbc IgM is present due to the immune response to the presence of the hepatitis core antigen and indicates an acute infection. Anti-HBs is generally interpreted as indicating recovery and immunity from hepatitis B virus infection, according to the CDC.

Concerning antigen-antibody reactions, the prozone effect causes which of the following results? False positive False negative No reaction at all Mixed field reaction

B Both antibody excess (prozone) and antigen excess (postzone) result in the formation of small antigen-antibody complexes. This results in false negative reactions because the number of agglutinated cells are decreased. False positive reactions may be caused by overcentrifugation, for example, which can cause red cells to adhere too strongly to the test tube and be difficult to shake loose. While prozone results in a false negative reaction, antigen-antibody reactions do still occur - they are just too small to see with the naked eye. Mixed field reactions are most commonly caused by a dual cell population which may occur if a patient has been recently transfused.

A lymphokine can BEST be described as: A soluble mediator produced by granulocytes and affecting lymphocytes A soluble mediator produced by lymphocytes A soluble mediator produced by plasma cells An antibody that reacts with lymphocytes

B Lymphokines are a type of cytokine that are produced by lymphocytes, usually T cells, to direct the immune system response by signaling between its cells. Lymphokines attract immune cells to an infected area and helps activate them to attack the foreign pathogens.

A hapten is only antigenic when it is coupled with which of the following: Enzymes Proteins Lymphocytes Thrombocyte

B The molecular weight of a hapten is by itself not sufficient to elicit an antibody response alone, but requires a carrier, usually a protein, to do so.

The antigen marker most closely associated with transmission of HBV infections is: HBsAg HBeAg HBcAg HBiAg

B The presence of HBeAg connotes active replication of hepatitis B virus, with a high degree of infectivity. HBsAg is the first marker to appear in HBV infection and indicates active infection. It is an important marker in detecting initial infection and is a required donor test. HBcAg and HBiAg are not actual components of HBV, nor are they tested for to determine the course of HBV infection.

The purpose of C3a and C5a, the split-products of the complement cascade, is to: Bind with specific membrane receptors of lymphocytes and cause release of cytotoxic substances. Cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils. Bind with membrane receptors of macrophages to facilitate phagocytosis and the removal of debris and foreign substances. Regulate and degrade membrane cofactor protein after activation by C3 convertase.

B The purpose of C3a and C5a, the split-products, of the complement cascade is to cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils. C3a and C5a, bioactive fragments of the complement components C3 and C5, respectively play a key role in mediation of immunologically provoked inflammatory responses. C3a and C5a are produced by the activation of the classical pathway and/or the alternative pathway.

Patients with Waldenstrom's macroglobulinemia demonstrate excessively increased concentrations of which of the following? IgG IgM IgA IgE

B Waldenstrom's macroglobulinemia is the result of lymphoplasmacytic lymphoma typically characterized by the production of a large amount of monoclonal IgM antibody.

What is the MOST likely cause when clinical signs indicate HIV infection, but antibody tests are negative? probably not HIV infection patient is in the "window phase" before antibody production tests were performed incorrectly

B When clinical signs indicate HIV infection, but antibody tests are negative, a patient can be in the "window phase" before antibody production. This means that the HIV viral antigens have yet not produced an immune response great enough for laboratory studies to detect anti-HIV antibodies. This window period can last up to 6 months after infection.

Which of the following would be considered most significant as it relates to serological testing: Presence of an antibody titer is generally diagnostic Rise of antibody titers is diagnostic Concentration of antibody is diagnostic Cross reactivity is not significant

B Serological diagnosis of active or recent infection generally requires the demonstration of IgM antibody, or the demonstration of a fourfold rise in the titer of specific IgG antibody.

What type of follow-up testing is recommended for a Speckled ANA pattern? None Testing for antibodies to the extractable nuclear antigens (ENA) Testing for antibodies to dsDNA

B Speckled ANA patterns are usually followed-up with testing for antibodies to the extractable nuclear antigens (ENA). Frequently this includes: Sm (Smith), U1-RNP, SSA/Ro, SSB/La, and Scl-70. Testing for dsDNA antibodies is usually done on homogeneous ANA patterns. However, some labs will suggest both dsDNA and ENA testing if the speckled pattern is greater than 1:160.

Why are ANA positive samples titered? (multiple answers are correct) A. To determine just how ill the patient is. B. To determine how much antibody is present in the sample. C. To look for multiple ANA patterns.

B and C There are two main reasons for titering ANA samples: to determine the amount of antibody present and to look for multiple ANA patterns. In the case of ANA testing the titer does not reflect disease severity. The higher the titer the more likely the patient has one of the systemic autoimmune rheumatic diseases (SARDs), however, titer levels do not necessarily change with disease activity or severity. Often one ANA pattern will mask over, or hide, another pattern. Titering can facilitate the detection of multiple patterns, alerting the clinician to possible disease associations and relevant follow-up testing.

Diseases associated with dysfunctions of polymorphonuclear neutrophils (PMNs) include all of the following EXCEPT: Chediak-Higashi syndrome (CH) Chronic granulomatous disease (CGD) Gaucher 's Disease Myeloperoxidase deficiency (MPO)

C Chediak-Higashi, chronic granulomatous disease, and myeloperoxidase deficiency are all dysfunctional neutrophil disorders. Gaucher's disease the most common lysosomal storage disease caused by insufficient activity of the lysosomal enzyme glucocerebrosidase that leads to the deposition of glucocerebroside in cells of the macrophage-monocyte system.

Which disease is MOST likely to show a homogenous pattern in an immunofluorescence (IF) microscopy test for ANA? Sjogren's syndrome CREST syndrome SLE Scleroderma

C In SLE, a homogeneous pattern is usually present, although SLE can also demonstrate a speckled pattern. A nucleolar pattern is commonly seen in scleroderma. A centromere pattern is common in CREST syndrome. Sjogren's is highly associated with a speckled ANA pattern.

Prozone is usually found in: Those tubes of titration which contain the least concentration of antibody The serum of a patient who has more than one antibody A patient sample in which the serum contains a high titer of antibody A patient sample in which the serum has been inactivated before titering

C Prozone is a phenomenon in which titers of specific antigen and antibody do not agglutinate or precipitate visibly because of an excess in antibody. Therefore the correct answer is "a patient sample in which the serum contains a high titer of antibody".

Skin and mucous membranes are important components of what part of the immune system? Cell mediated immunity Adaptive immunity Innate immunity Acquired immunity

C Skin and mucous membranes along with other functions such as phagocytosis, complement, acute phase proteins and others are all part of natural or innate immunity. This protection is non-specific and is readily available. Cell mediated is primarily part of the adaptive/acquired or specific immune system, involving the activity of T lymphocytes. Adaptive immunity involves the recognition of a foreign antigen and a specific humoral (antibody) or cell mediated response. Acquired immunity is another name for adaptive or specific immunity.

Which of the following is the "activation unit" in the classical complement pathway? C1 C2 C4, C2, C3 C5, C6, C7, C8, C9 C1, C2, C9

C The combination of complement C4, C2 and C3 that binds to the antigen-antibody complex in the initial reaction step in the classical pathway of complement activation is called the activation unit.

Which one of the following statements is FALSE? Fever can have a direct effect on the growth or death of pathogenic microorganisms. Low pH of stomach, skin, and vagina can inhibit microbial growth. Secretory cells of the innate immune system are antigen specific. Oxygen tension can result in the death of microorganisms due to oxidation.

C The innate immunity system is inherent and nonspecific; meaning that all pathogens are attacked similarly and are not antigen specific.

For the ANA test to be positive what must be present in the nucleus of the interphase cell? Strong staining Centromeres dsDNA A clearly discernible pattern

D A clearly discernible pattern is correct. The strength of the reaction doesn't matter, only that it is clearly discernible. Centromere and dsDNA are just some of the many different antigens, however, without the corresponding (cognate) antibodies from the patient sample there is no ANA pattern. Remember, to be ANA positive there must be a clearly discernible pattern in the nucleus of the interphase cells.

Antigen processing is primarily accomplished by which cell type? Basophils Eosinophils Polymorphonuclear neutrophils Macrophages

D After digesting a pathogen, a macrophage will present the antigen on its cell surface to the corresponding helper T cell. The presentation is done by integrating it into the cell membrane and displaying it attached to an MHC class II molecule, indicating to other white blood cells that the macrophage is not a pathogen, despite having antigens on its surface

Which of the following is not a feature of systemic lupus erythematosus (SLE): Increased serum complement Positive ANA Circulating immune complexes Decreased serum complement

D Complement is actually consumed during the immune reactions involved in SLE. Therefore, a decrease in complement is expected. Circulating immune complexes and a positive anti nuclear antibody (ANA) test are both usually present in patients with SLE.

Which of the following immunoglobulin classes is chiefly responsible for the degranulation of mast cells and basophils? IgG IgA IgM IgE

D IgE levels are often increased in patients with allergic disease. IgE binds to the membranes of mast cells and basophils, and if specific antigen is present to react with the IgE molecule, degranulation of these cells occurs, releasing histamines, and other substances into the blood or tissues. IgG, IgG, and IgM are not associated with the degranulation of mast cells and basophils.

The part of the immunoglobulin molecule that may be kappa or lambda chains is: Fc Fab Heavy chains Light chains

D Light chains must always be either the kappa or lambda types in the formation of an antibody.

The term TITER ( as it applies to the measurement of antibodies) is best defined as: Concentration of antibody in the serum Maximum reactive dilution X 100 Maximum reactive dilution / 100 Reciprocal of maximum reactive dilution

D The term TITER ( as it applies to the measurement of antibodies) is best defined as reciprocal of maximum reactive dilution of the patient's serum where the antibody is still detectable. For example, a specimen with a last reacting tube containing a 1:100 dilution, would be said to have a titer of 100.

Contact dermatitis is mediated by: B lymphocytes Macrophages Polymorphonuclear cells T lymphocytes

D When an antigen comes in contact with the skin, the antigen is processed by cells in the epidermis and come in contact with T lymphocytes. T lymphocytes recognize the antigen as foreign and circulate through the bloodstream back to the epidermis and produce an inflammatory response to eliminate the antigen, but this immune response can produce a characteristic rash in the skin called contact dermititis.

Determining viral load is how one determines a positive diagnosis for HIV infection. True False

False Determining viral load is a way to monitor already infected individuals with HIV and other viral diseases. The viral load can show how well treatments are working, show potential medication resistance, and also indicate relapses.

The 5' end of a DNA strand ends with a OH group. True False

False The 5' end of a DNA strand is distinguished by a phosphate while the 3' end is distinguished by a OH group.