BOC 7TH EDITION : IMMUNOLOGY AND SEROLOGY

A DPT vaccination is an example of:

a active humoral-mediated immunity

b passive humoral-mediated immunity

c cell-mediated immunity

d immediate hypersensitivity

a Vaccines stimulate the host to produce antibodies against a specific antigen to prevent disease.

Cells known to be actively phagocytic include:

a neutrophils, monocytes, basophils

b neutrophils, eosinophils, monocytes

c monocytes, lymphocytes, neutrophils

d lymphocytes, eosinophils, monocytes

b Lymphocytes and basophils are not phagocytic.

Normal serum constituents that can rapidly increase during infection, injury or trauma are referred to as:

a haptens

b acute phase reactants

c opsonins

d chemotaxins

b This is the definition of acute phase reactants.

The acute phase reactant that has the fastest response time and can rise 100x is:

a alpha-1 antitrypsin

b haptoglobin

c c-reactive protein

d ceruloplasmin

c CRP response time is typically 4-6 hours with levels a 100x to a 1000x higher and peaking around 48 hours.

Acquired immunity can be characterized as having what qualities?

a nonadaptive and nonspecific

b internal and external mechanisms

c sensitivity and short acting

d specificity and memory

d Specificity and memory are hallmarks of acquired immunity.

Skin, lactic acid in sweat, pH balance, mucous, and the motion of cilia represent which type of immunity?

a natural, innate

b acquired

c adaptive

d auto

a The list of components in the stem are all naturally occurring and do not require the activation of the immune system to be present or functional.

Substances that are antigenic only when coupled to a protein carrier are:

a opsonins

b haptens

c adjuvants

d allergens

b This is the definition of a hapten.

A haptenic determinant will react with:

a both T cells and antibody

b T cells but not antibody

c neither T cells nor antibody

d antibody but not T cells

d In the immune response to a hapten carrier complex, the hapten portion of the molecule binds to B cells, while the carrier portion binds to T cells, and the B cell is stimulated to produce hapten-specific antibody.

Antibodies composed of IgG immunoglobulin:

a occur during the primary response to antigen

b are larger molecules than IgM antibodies

c can cross the placenta from mother to fetus

d can be detected in saline crossmatches

c Biological functions of immunoglobulins; IgG crosses the placenta.

Cells that are precursors of plasma cells and also produce immunoglobulins are:

a macrophages

b B lymphocytes

c T lymphocytes

d monocytes

b Biological functions of lymphocytes; B cells make antibody, and become plasma cells.

Antibodies are produced by:

a killer cells, T cells

b marrow stem cells

c mast cells

d B cells

d The function of B cells is to produce antibodies.

Polyclonal B-cell activation:

a inhibits antibody production

b requires the participation of T-helper cells

c results from the activation of suppressor T cells

d can induce autoantibody production

d Autoimmunity, theories of how it develops.

Macrophages are characterized by:

a surface receptors for C3b complement

b surface CD3 expression

c in vitro synthesis of immunoglobulin

d large amounts of rough endoplasmic reticulum

a Macrophages have surface receptors for C3b.

Macrophage phagocytosis of bacteria is enhanced by which of the following:

a opsonin

b antigen

c hapten

d secretory piece

a Macrophage phagocytosis is enhanced by opsonins.

Humoral antibodies are produced by which cells?

a macrophages

b T lymphocytes

c B lymphocytes

d neutrophils

c B cells make humoral antibodies.

In hybridoma technology, the desirable fused cell is the:

a myeloma-myeloma hybrid

b myeloma-lymphocyte hybrid

c lymphocyte-lymphocyte hybrid

d lymphocyte-granulocyte hybrid

b Monoclonal antibodies are produced by cells that are a fused hybrid of a mouse spleen cell with a mouse myeloma cell. The spleen cell confers the antibody specificity, and the tumor cells give it the ability to keep reproducing.

Which test is used to evaluate the cellular immune system in a patient?

a skin test for commonly encountered antigens

b determination of isohemagglutinin titer

c immunoelectrophoresis of serum

d lymphocyte proliferation to mitogen/antigen

a Skin tests are used to determine whether the delayed-type hypersensitivity response mediated by T cells is functioning properly. All other tests listed evaluate humoral antibody responses.

T cells are incapable of:

a collaborating with B cells in antibody responses

b secretion of immunoglobulins

c secretion of cytokines

d producing positive skin tests

b While T cells help B cells in the process of antibody production, they are not capable of secreting immunoglobulins themselves. Immunoglobulins are produced only by B cells and plasma cells.

T lymphocytes are incapable of functioning as:

a cytotoxic cells

b helper cells

c phagocytic cells

d regulatory cells

c Phagocytosis is mediated by macrophages and neutrophils, not by lymphocytes.

Nonspecific killing of tumor cells is carried out by:

a cytotoxic T cells

b helper T cells

c natural killer cells

d antibody and complement

c Natural killer cells do not specifically bind to tumor antigens, as do T lymphocytes and antibodies, and can kill tumor cells without having had prior exposure to them.

When a natural killer cell comes in contact with a cell expressing MHC class I proteins what action will result?

a perforins released

b granzymes released

c inhibition of killing

d cytotoxic mechanisms

c NK cells distinguish healthy cells from infected or cancerous cells by recognizing the major histocompatibility complex (MHC) Class I, which is expressed on all healthy cells.

Some MHC class III genes code for?

a antigens

b antibodies

c lymphocytes

d complement

d MHC Class I codes for HLA-A, B, and C. MHC Class II codes for HLA-DR, DQ, and DP. MHC Class III codes for complement and cytokines.

Which of the following is an important cellular mediator of immune complex tissue injury?

a mast cell

b neutrophil

c basophil

d eosinophil

b The tissue damage resulting from type III hypersensitivity is caused by the deposition of immune complexes, which recruit neutrophils to the tissues. The neutrophils release their lysosomal enzymes, resulting in inflammation and damage to the surrounding tissues.

Which of the following mediators is released during T-cell activation?

a immunoglobulins

b complement C3

c histamine

d cytokines

d While B cells are involved in humoral immunity through the production of antibodies, T cells mediate their responses through the release of soluble proteins called cytokines.

MHC Class I includes which molecules?

a complement

b HLA A, B, C

c cytokines

d HLA DP, DQ, DR

b MHC Class I codes for HLA-A, B, C. MHC Class II codes for HLA-DR, DQ, DP. MHC Class III codes for complement and cytokines.

C3b and Fc receptors are present on:

a B lymphocytes

b monocytes

c B lymphocytes and monocytes

d neither B lymphocytes nor monocytes

c Receptors for the C3b component of complement and for the Fc portion of immunoglobulin are found both on B cells and on monocytes, and are thought to play a role in the clearance of immune complexes.

T lymphocytes that possess the CD8 surface marker mediate which of the following T-cell functions?

a delayed-type hypersensitivity

b regulatory

c cytotoxic

d helper

c Cytotoxic T cells, which are capable of destroying targets such as tumor cells and virus-infected cells, bear the CD8 surface marker, while the other cell types listed are positive for the CD4 surface marker.

A normal control for a B lymphocyte enumeration assay should have a value of what percentage of total lymphocytes counted?

a 21%

b 48%

c 76%

d 89%

a Normal peripheral blood should contain approximately 80% T lymphocytes and 20% B lymphocytes.

An immunofluorescence test using reagent antibody directed against the CD3 surface marker would identify which of the following cell types in a sample of human peripheral blood?

a all mature T lymphocytes

b T helper lymphocytes only

c cytotoxic T lymphocytes only

d T regulatory cells only

a CD3 is a marker used to identify T lymphocytes. It is present on the surface of all mature T cells, regardless of T-cell subset.

Which of the following cytokines is produced by an activated CD8 cytotoxic T cell?

a interleukin 13 (IL-13)

b interleukin 5 (IL-5)

c stromal cell-derived factor 1 (SDF-1)

d interferon gamma (IFNy)

d IL-13 and IL-5 are examples of T-helper type 2 (Th2) cytokines, which means they are produced by Th2 CD4 T cells. SDF-1 is a chemokine (not a cytokine) produced by stromal cells. IFNy is a potent effector cytokine that is produced by activated CD8 cytotoxic T cells. Activated T-helper type 1 (Th1) CD4 T cells can also produce IFNy.

What is the location of B-cell maturation?

a thymus

b spleen

c bone marrow

d liver

c B cells develop from common lymphoid progenitors in the bone marrow until the mature B-cell stage after which they leave the marrow for secondary lymphoid organs. B cells do not develop in the thymus or other organs, such as liver and kidneys.

What is the location of T-cell maturation?

a bone marrow

b gut-associated lymphoid tissue (GALT)

c thymus

d kidneys

c T cells leave the bone marrow early in their development, and then move to the thymus for further development. T cells develop primarily in the thymus. B cells do not develop in the thymus or other organs, such as liver and kidneys.

A living microbe with reduced virulence that is used for vaccination is considered:

a dormant

b virulent

c attenuated

d denatured

c Attenuated vaccines consist of live, whole bacterial cells or viral particles that are treated in such a way that they have reduced virulence within the host but retain the ability to induce an immune response. Denatured vaccines are not live, and toxoids are chemically modified toxins from a pathogen. Dormant and virulent microbes are not used for vaccination.

Measurement of serum levels of which of the following immunoglobulins could serve as a screening test for multiple allergies?

a IgA

b IgE

c IgG

d IgM

b Biological functions of immunoglobulins: IgE is the antibody involved in multiple allergies.

IgM antibodies are frequently hemolytic because of:

a their dimeric structure

b the molecule's 5 antigen-binding sites

c their sedimentation coefficient of 7-15 S

d their efficient ability to fix complement

d Biological functions of immunoglobulins: IgM binds complement well and is hemolytic.

To which of the following classes do the antibodies that cause hemolytic disease of the newborn belong?

a IgA

b IgE

c IgG

d IgD

c Biological functions of immunoglobulins: IgG antibody crosses the placenta and is involved in hemolytic disease of the newborn.

The first isotype of immunoglobulin made by the fetus that may be elevated in cases of in-utero infection is:

a IgA

b IgG

c IgM

d IgD

c Neonate IgG comes from the mother, but if there is elevated IgM (the first immunoglobulin made by the fetus), an in utero or neonatal infection is indicated.

The immunoglobulin classes most commonly found on the surface of circulating B lymphocytes in the peripheral blood of normal persons are:

a IgM, IgA

b IgM, IgG

c IgM, IgD

d IgM, IgE

c IgM and IgD are the isotypes of immunoglobulin that are found on most circulating B cells. They are in effect the B-cell receptor.

Antibody class/isotype and antibody subclass are determined by major physiochemical differences and antigenic variation found primarily in the:

a constant region of heavy chain

b constant region of light chain

c variable regions of heavy and light chains

d constant regions of heavy and light chains

a The constant region of the heavy chain determines the biological function of the immunoglobulin and defines the immunoglobulin into 1 of 5 subclasses.

The ratio of kappa to lambda light chain-producing cells in normal individuals is:

a 1:1

b 2:1

c 3:1

d 4:1

b The immunoglobulin molecule is made up of 1 or more units (# of units depending on heavy chain type) composed of 2 heavy chains and 2 light chains. The light chains can be either the kappa or lambda type. About 65% of the human immunoglobulin molecules have kappa chains and 35% have lambda chains.

Which of the following immunoglobulin isotypes is associated with a secretory component (transport piece)?

a IgA

b IgD

c IgE

d IgG

a A secretory IgA molecule is composed of 2 units of 2 heavy chains and 2 light chains. These chains are joined by the J-chain, and are protected from the harsher environment where they are secreted by an additional chain called the transport piece.

The immunoglobulin class typically found to be present in saliva, tears and other secretions is:

a IgG

b IgA

c IgM

d IgD

b Immunoglobulin A (IgA) is the most abundant immunoglobulin in saliva, tears, and other mucosal secretions and plays an important role in mucosal immunity.

Treatment of IgG with papain results in how many fragments from each immunoglobulin molecule?

a 2

b 3

c 4

d 5

b Papain cleaves IgG into 2 Fab fragments and 1 Fc fragment.

The immunoglobulin isotype associated with immediate hypersensitivity or atopic reactions is:

a IgA

b IgM

c IgD

d IgE

d Immunoglobulin function: IgE is the immunoglobulin involved with allergy.

Which of the following immunoglobulins is the most efficient at agglutination?

a IgG

b IgA

c IgM

d IgE

c Immunoglobulin function: IgM is best at agglutination.

Antibodies to which of the following immunoglobulins is known to have produced anaphylactic reactions following blood transfusion?

a IgA

b IgD

c IgE

d IgG

a Immunoglobulin deficiency; patients with IgA deficiency can have an anaphylactic reaction during transfusions.

The key structural difference that distinguishes immunoglobulin subclasses is the:

a number of domains

b stereometry of the hypervariable region

c the sequence of the constant regions

d covalent linkage of the light chains

c Immunoglobulin subclasses differ from each other in their Fc regions; this is the reason that the different classes have different biological function. The Fc region is the region that is crystallizable after papain cleavage. It varies in sequence in the different classes of immunoglobulin.

Immunoglobulin idiotypic diversity is best explained by the theory of:

a somatic mutation

b germ line recombination

c antigen induction

d clonal selection

b The diversity sequence of the variable region, which is expressed as many idiotypic differences, is what allows so many different antigens to be bound by antibody. This huge diversity in the variable region develops due to VDJ recombinant events for the heavy chain and VJ recombinant events for the light chain.

Which class of immunoglobulin is thought to function as an antigenic receptor site on the surface of immature B lymphocytes?

a IgD

b IgE

c IgA

d IgG

a The main function of IgD is in B-cell development; it is the isotype of surface immunoglobulin on immature B cells.

The IgM molecule is a:

a dimer

b trimer

c tetramer

d pentamer

d Immunoglobulin structure: IgM is a pentamer.

Which of the following immunoglobulins is present in the highest concentration in normal human serum?

a IgM

b IgG

c IgA

d IgE

b IgG is highest in concentration in normal sera.

Which of the following statements about immunoglobulins is true?

a immunoglobulins are produced by T lymphocytes

b lgA class is determined by the gamma heavy chain

c IgA class exists as serum and secretory molecules

d there are only 2 subclasses of IgG

c Immunoglobulin structure: IgA is present in serum and secretions.

Membrane-bound immunoglobulin molecules:

a have an additional amino-terminal sequence of about 40 residues

b are not anchored in a transmembrane configuration

c are anchored by a hydrophobic sequence of about 26 residues

d are anchored by a hydrophilic region

c IgD and surface IgM are anchored in the B-cell membrane; in order to be anchored in the membrane, they must contain a hydrophobic region. The hydrophobic region is about 26 residues long.

The area of the immunoglobulin molecule referred to as the hinge region is located between which domains?

a VH and VL

b CH1 and CH2

c CH2 and Снз

d CH3 and VL

b Immunoglobulin structure: hinge is between CH1 and CH2.

Antibody idiotype is dictated by the:

a constant region of heavy chain

b constant region of light chain

c variable regions of heavy and light chains

d constant regions of heavy and light chains

c Immunoglobulin structure: idiotype is in variable regions of heavy and light chains.

Antibody allotype is determined by the:

a constant region of heavy chain

b constant region of light chain

c variable regions of heavy and light chains

d constant regions of heavy and light chains

d Immunoglobulin allotype is in constant regions of heavy and light chains.

Which IgG subclass is most efficient at crossing the placenta?

a IgG1

b IgG2

c IgG3

d IgG4

a Immunoglobulin IgG subclass function; lgG1 goes through placenta best.

The J-chain is associated with which of the following immunoglobulins?

a IgA

b IgG

c IgE

d IgD

a Immunoglobulin structure: J-chain associated with IgA.

Bence Jones proteins are:

a immunoglobulin catabolic fragments in the urine

b monoclonal light chains

c whole immunoglobulins in the urine

d Fab fragments of a monoclonal protein

b Definition of Bence Jones protein.

Which 2 immunoglobulin classes have a J-chain associated with the structure?

a IgG, IgA

b IgA, IgE

c IgG, IgM

d IgM, IgA

d IgM and IgA have a J-chain, which serves as a linkage point for disulfide bonds between 2 adjacent monomers.

Avidity may be defined as the:

a degree of hemolysis

b titer of an antigen

c dilution of an antibody

d strength of a reacting antibody

d Avidity is the sum of the interactions between all interacting antigen epitopes and Fab sites, and describes the strength of the interaction of an antibody with its antigen.

The strength of a visible reaction is known as:

a prozone reaction

b absorption

c avidity

d elution

c Avidity is the sum of the interactions between all interacting antigen epitopes and Fab sites, and describes the strength of the interaction of an antibody with its antigen.

Which of the following describes an antigen-antibody precipitation reaction of non-identity?

a precipitin lines cross, forming double spurs

b precipitin lines fuse, forming a single spur

c no precipitin lines are formed

d precipitin lines fuse, forming a single arc

a Non-identity: each antigen forms an independent precipitin line with the corresponding antibody at an equivalence point.

Which test has the greatest sensitivity for antigen detection?

a precipitin

b agglutination

c ELISA

d complement fixation

c ELISA is a solid-phase immunoassay that uses anti-immunoglobulins that are labeled with an enzyme that can be detected by the appearance of color on the addition of a substrate.

Excess antigen in precipitation gel reactions will:

a have no effect on the precipitate reaction

b not dissolve precipitate after formation

c enhance the precipitate reaction

d dissolve the precipitate after formation

d Precipitation does not occur due to lack of free antibody. With excess amounts of antigen, equilibrium shifts to favor small lattice size, dissolving precipitate.

Soluble immune complexes are formed under the condition of:

a antigen deficiency

b antigen excess

c antibody excess

d complement

b Upon the addition of antigen to a fixed quantity of antibody, immune complexes start forming immediately. As more antigen is added, the reaction moves to antigen excess. Precipitation does not occur due to lack of free antibody.

The visible serological reaction between soluble antigen and its specific antibody is:

a sensitization

b precipitation

c agglutination

d opsonization

b Precipitation takes place when antibodies and soluble antigens are mixed.

c. The proportion of antigen to antibody in the zone of equivalence, shown as c in the figure, is optimal, ie, where antibody and antigen multivalent sites are equal for maximal precipitation.

The curve is obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum. The area on the curve for equivalence precipitate is:

a. a

b. b

c. c

d. d

d. Excess of antigen results in soluble complexes.

The curve is obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum. The area on the curve where no precipitate formed due to antigen excess is:

a. a

b. b

c. c

d. d

a. Prozone: suboptimal precipitation occurs in the region of antibody excess. Prozone effect: Occasionally, it is observed that when the concentration of antibody is high (ie, lower dilutions), there is no agglutination and then, as the sample is diluted, agglutination occurs. The lack of agglutination at high concentrations of antibodies is called the prozone effect. Lack of agglutination in the prozone is due to antibody excess resulting in very small complexes that do not clump to form visible agglutination.

The curve is obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum. The area on the curve for prozone is:

a. a

b. b

c. c

d. d

d. As more antigen is added beyond the optimal concentration where antibody and antigen mulivalent sites are equal, formation of precipitate decreases, and this area of the curve is depicted on the figure as d. As antigen begins to exceed antibody, equilibrium begins to favor soluble complexes, and precipitation of antigen-antibody complexes is reversed.

The curve is obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum. The area on the curve where soluble antigen-antibody complexes have begun to form is:

a. a

b. b

c. c

d. d

b. As more antigen is added, formation of precipitate increases, and this area of the curve is depicted on the figure as b. Once optimal concentration of antigen is reached, maximal precipitation occurs in the zone of optimal concentration, or zone of equivalence (c in the figure) where antibody and antigen mulivalent sites are equal, and after this point, adding more antigen would not further increase the amount of precipitate.

The curve is obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum. The area in which the addition of more antigen would result in the formation of additional precipitate is:

a. a

b. b

c. c

d. d

a A continuous coalescing precipitin line forms when the 2 antigens are identical, the pattern of identity.

Which of the figures demonstrates a reaction pattern of identity?

a figure 1

b figure 2

c figure 3

d figure 4

b Two related antigens form independent precipitin lines that form a single spur, the pattern of partial identity.

Which of the figures demonstrates a reaction pattern of partial identity?

a figure 1

b figure 2

c figure 3

d figure 4

c Two nonrelated antigens form independent precipitin lines that cross over each other, the pattern of nonidentity.

Which of the figures demonstrates a reaction pattern of nonidentity?

a figure 1

b figure 2

c figure 3

d figure 5

d When 2 parallel precipitin lines exist, it indicates that there are 2 distinct antigenic molecular species present. The identity arc indicates that the 2 antigens are identical in figure 1. Figure 2, partial identity, shares a determinant that is part of antigen 1.

Which of the figures demonstrates a reaction pattern showing 2 different antigenic molecular species?

a figure 1

b figure 2

c figure 3

d figure 4

d If the antibody well is surrounded by a precipitin circle, there is a nonspecific precipitin reaction to that antibody. The identity arc indicates that the 2 antigens are identical in figure 1. Figure 2, partial identity, shares a determinant that is part of antigen 1.

A nonspecific precipitin reaction is demonstrated in which of the figures?

a figure 1

b figure 3

c figure 4

d figure 5

A series of 8 tubes are set-up with 0.79 mL of diluent in each. A serial dilution is performed by adding 10 uL of serum to the first tube and then transferring 10 uL through each remaining tube. What is the serum dilution of tube 7?

a 1:2.431 × 10^11

b 1:2.621 × 10^11

c 1:1.920 × 10^13

d 1:2.097 × 10^13

d A dilution involves the solute, the material being diluted and the diluent. 1/dilution = (amount of solute)/(total volume). In the problem, the 8th tube is diluted.

The enzyme control tube in an ASO hemolytic assay exhibits no cell lysis. What is the most likely explanation for this?

a incorrect pH of buffer

b low ionic strength buffer

c oxidation of the enzyme

d reduction of the enzyme

d ASO is an enzyme inhibition test. In the ASO test, a serum results in inhibition of the reagent's enzymatic ability to lyse human red blood cells.

c Prozone: suboptimal precipitation occurs in the region of antibody excess. Occasionally, it is observed that when the concentration of antibody is high (ie, lower dilutions), there is no agglutination and then, as the sample is diluted, agglutination occurs. The lack of agglutination at high concentrations of antibodies is called the prozone effect. Lack of agglutination in the prozone is due to antibody excess resulting in very small complexes that do not clump to form visible agglutination.

This pattern of agglutination is observed in an antibody titration. This set of reactions most likely resulted from:

a faulty pipetting technique

b postzoning

c prozoning

d the presence of a high-titer, low-avidity antibody

Which of these substances will not stimulate an immune response unless it is bound to a larger molecule?

a antigen

b adjuvant

c hapten

d antibody

c A hapten is a small molecule that can act as antigen if it binds to a larger protein molecule. Antigens, viruses and antibodies can stimulate an immune response on their own depending on the context of stimulation. Adjuvants are compounds used to stimulate the immune response to an antigen in a vaccine preparation. They do not directly serve as antigens.

Blood is drawn from a patient for serological tests for a viral disease shortly after the time of onset and again 4 weeks later. The results of the tests are considered diagnostic if the:

a first antibody titer is 2x the second

b first and second antibody titers are equal

c first antibody titer is 4x the second

d second antibody titer is at least 4x the first

d A 4-fold or greater increase in antibody titer from second of 2 serum specimens taken from a patient during the acute and convalescent phases of an infection is considered to be diagnostic.

The best method to detect infections due to rubella, Epstein-Barr and human immunodeficiency viruses is:

a antigen detection by EIA

b cell culture

c antigen detection by Western blot

d antibody detection by EIA

d Serological tests are commonly used to detect antibodies in infections with viruses that are difficult to culture, such as rubella, HIV, and EBV. EIA is a common serological method because it is sensitive, specific, and can be automated.

Immunoassays are based on the principle of:

a separation of bound and free analyte

b antibody recognition of homologous antigen

c protein binding to isotopes

d production of antibodies against drugs

b "Immunoassay" is a general term for an assay involving binding of an antibody to a specific antigen.

What kind of antigen-antibody reaction would be expected if soluble antigen is added to homologous antibody?

a precipitation

b agglutination

c complement fixation

d hemagglutination

a By definition, precipitation involves combination of antigen and soluble antibody to form insoluble complexes that fall out of solution.

a A cold agglutinin titer is read as the last dilution showing agglutination at 4°C.

The best interpretation of the cold agglutinin titer results show in this table is:

a positive, 1:128

b negative

c invalid because 37°C reading is negative

d repeat the 4°C readings

In an indirect ELISA method designed to detect antibody to the rubella virus in patient serum, the conjugate used should be:

a anti-human IgG conjugated to an enzyme

b anti-rubella antibody conjugated to an enzyme

c rubella antigen conjugated to an enzyme

d anti-rubella antibody conjugated to a substrate

a In an indirect ELISA, patient antibody to an antigen (eg, rubella antigen) is detected by addition of an enzyme-labeled antibody to human immunoglobulin, which, in turn, binds to the patient's IgG.

In immunofixation electrophoresis:

a the antibody reacts with the antigen and then the complex is electrophoresed

b the antigen is electrophoresed into an antibody containing gel

c the antigen is electrophoresed and then monospecific antisera is reacted with it

d the antigen is electrophoresed, transferred to nitrocellulose and then antibody reacts with itand an ElA is performed

c In immunoelectrophoresis, first the serum is separated in an agarose gel by electrophoresis; then, in a trough that is cut parallel to the plane of the electrophoresis, antiserum is placed. The antibody diffuses toward the serum proteins, and arcs of antibody-antigen precipitation occur.

A single test that could reliably detect neonatal infection in the absence of clinical signs is:

a serum immunoelectrophoresis

b differential leukocyte count

c CD4 cell counts

d quantitative serum IgM determination

d An elevated IgM level indicates an in utero or neonatal infection.

The serological test that can be modified to selectively detect only specific IgM antibody in untreated serum is:

a Ouchterlony

b enzyme immunoassay

c hemagglutination inhibition

d passive hemagglutination

b Indirect labeled assays can be designed to utilize class-specific antihuman immunoglobulin, that is IgM specific.

What is the immunologic method utilized in the flow cytometer?

a latex agglutination

b enzyme linked immunoassay

c immunofluorescence

d radioimmunoassay

c Flow cytometry uses fluorescent-labeled monoclonal antibodies to identify cells of interest by binding to specific components within or on the surface of the cells

The assembly of the complement "membrane attack unit" is initiated with the binding of:

a C1

b C3

c C4

d C5

d In the complement cascade, the membrane attack unit begins with C5.

Which of the following is most likely to activate the alternative pathway of complement activation?

a lipopolysaccharides

b glycoproteins

c haptens

d IgG complexed with antigen

a Lipopolysaccharides initiate the alternative pathway of complement.

Which of the following is the larger residual split portion of C3?

а СЗа

b СЗb

c C4

d Clq

b C3 breaks down to a small C3a, which floats away and is an anaphylatoxin. The larger C3b, which lands on the target surface and becomes part of C5 convertase, is also a powerful opsonin.

Which of the following activities is associated with C3b?

a opsonization

b anaphylaxis

c vasoconstriction

d chemotaxis

a C3 breaks down to a small C3a, which floats away and is an anaphylatoxin. The larger C3b, which lands on the target surface and becomes part of C5 convertase, is also a powerful opsonin.

Which of the following is the "recognition unit" in the classical complement pathway?

a C1q

b C3a

c C4

d C5

a Complement C1q is the recognition unit.

Which of the following is the "membrane attack complex" of complement activation?

a C1

b C3

с С4, С2, СЗ

d C5b, C6, C7, C8, C9

d Complement, C5-C9, is the membrane attack complex.

Which of the following releases histamine and other mediators from basophils?

а СЗа

b properdin factor B

c Clq

d C4

а C3a, C4a and C5a are anaphylatoxins and cause release of histamine from basophils and mast cells.

Which of the following is not a mechanism involved in the complement cascade?

a apoptosis

b opsonization

c inflammation

d cytolysis

a Apoptosis is programmed cell death and is not involved in the complement cascade.

The activation mechanism of the alternative complement pathway is initiated differently from that of the classical pathway because, in the alternative pathway:

a antigen-antibody complexes containing IgM or IgG are required

b endotoxin alone cannot initiate activation

c C1 component of complement is involved

d antigen-antibody complexes containing IgA or IgE may initiate activation

d IgA and IgE do not initiate the classical pathway of complement but can initiate the alternative pathway.