6,8,9,10
Characterization of antigens by electrophoresis and immunofixation relies on the reaction of antigen and antibody in (or on): A Agar. B Streptavidin. C Gold-plated sensor chip. D Latex particles. E Plastic microtiter plates.
Agar. The antigen moves in the agar as a band of defined electrophoretic mobility and is fixed by overlaying with a specific antibody which identifies the antigen.
Latex particles are often used in: A Agglutination tests. B Affinity chromatography. C Affinity measurements. D Adjuvants. E Neutralization assays.
Agglutination tests.
Relative to males, females: A Are less resistant to T-cell tolerance. B Are more susceptible to autoimmune disease. C Produce lower antibody responses to T-independent antigens. D Have lower serum Ig levels. E Have lower levels of secretory IgA.
Are more susceptible to autoimmune disease.
Natural antibodies: A Are mostly IgG. B Are mostly high affinity autoantibodies. C Are produced spontaneously by CD5+ B-cells. D Are acquired by transplacental passage from the mother. E Do not arise in thymectomized mice.
Are produced spontaneously by CD5+ B-cells.
Regulatory idiotypes on antibodies: A Are not usually 'public' idiotypes. B Are not usually 'cross-reactive' idiotypes. C Are usually common to several different antibodies. D Are usually 'private' idiotypes . E Are usually restricted to members of a single clone of antibodies.
Are usually common to several different antibodies.
With respect to immunoneuroendocrine networks: A They do not exist. B They exist only in higher primates. C They never involve ACTH. D They never involve the hypothalamic/pituitary axis. E Augmentation of glucocorticoid production by IL-1 is a good example.
Augmentation of glucocorticoid production by IL-1 is a good example. IL-1 acts through the hypothalamus and pituitary to increase ACTH production which acts on the adrenal to augment glucocorticoids which suppress immune responses.
Dendritic cells can be driven from a resting state to an activated state by the T-cell surface molecule: A TCR B CD40L C CD28 D B7 E CD40
CD40L CD40 ligand (CD154) on the T-helper cell engages CD40 on the resting dendritic cell, resulting in upregulation of costimulatory molecules such as B7 on the now activated dendritic cell.
Activated memory T-cells can be distinguished from naive T-cells on the basis of expression of: A T-cell receptor. B Immunoglobulin. C MHC class II molecules. D CD45RO. E IL-1.
CD45RO
T-cell mediated suppression: A Is always mediated by CD8+ T-cells. B Is always mediated by CD4+ T-cells. C Can be due to Th2 cells suppressing Th1 by IL-4 or IL-10. D Does not exist. E Cannot transfer suppression to another animal.
Can be due to Th2 cells suppressing Th1 by IL-4 or IL-10.
Cytokines: A Are usually around 150-200 kDa. B Have glycosyl phosphatidylinositol (GPI) anchors. C Can be pleiotropic. D Generally act at long range. E Produce very stable long-lived messenger RNA.
Can be pleiotropic. Cytokines can exhibit multiple effects on growth, differentiation and activation of a variety of cell types
Antibodies specific for different epitopes on the same antigen: A Will usually bind to each other through idiotypic interactions. B Cannot bear similar idiotypes. C Can bear similar idiotypes independently of their antigenic specificity. D Can only bear similar idiotypes if the antigenic epitopes cross-react. E Must be of the same immunoglobulin class.
Can bear similar idiotypes independently of their antigenic specificity.
Idiotype-anti-idiotype interactions: A Do not involve antigen-specific receptors. B Only involve antibodies. C Can mediate a lymphocyte network in early life. D Do not occur within the CD5+ B-cell population. E Do not involve self-reactivity.
Can mediate a lymphocyte network in early life.
In affinity chromatography the required ligand is often released by: A Changing the pH B Vigorous shaking C Changing the temperature from 37° to 4°. D Boiling. E Adding a small amount of detergent (e.g. 0.025% Tween 20).
Changing the pH Antigen-antibody bonds can be disrupted by changing the pH or adding chaotropic agents such as thiocyanate.
The first event following the production of CH sterile transcripts by immunoglobulin genes is: A VDJ rearrangement. B Light chain rearrangement. C Somatic hypermutation. D Apoptosis. E Class switching.
Class switching.
The major long term source of a foreign antigen in the body is: A Anti-idiotype. B Complexes on the surface of follicular dendritic cells. C Antigen bound to the surface of B-cells. D Antigenic peptides in the groove of MHC molecules. E There are no long term sources of foreign antigen in the body.
Complexes on the surface of follicular dendritic cells.
CD8 is a marker of: A B-cells B Helper T-cells C Cytotoxic T-cells D An activated macrophage E A neutrophil precursor
Cytotoxic T-cells
Cells bearing MHC class I plus peptide are targets for specific: A B-cells. B Cytotoxic T-cells. C Th1 cells. D Th2 cells. E Interdigitating dendritic cells.
Cytotoxic T-cells are guided by their antigen receptor plus CD8 to target cells bearing MHC class I plus peptide
Antibody-secreting cells can be enumerated by: A Mitosis. B Cytokine release. C Total antibody content. D Cell surface immunoglobulin. E ELISPOT.
ELISPOT. Each antibody-secreting cell can form an individual ELISA spot so allowing their enumeration.
The pepscan technique is most useful for determining: A Antibody structure. B Discontinuous epitopes recognized by antibodies. C Epitopes recognized by T-cells. D MHC haplotypes. E TCR V beta usage.
Epitopes recognized by T-cells. Cleavable peptides synthesized on pins provide molecules which can be used to determine epitopes which will bind to MHC molecules and be presented to the T-cell receptor.
Memory T-cells: A Are continuously produced directly from naive progenitors without the need for antigenic stimulation. B Express high levels of CD44. C Are only present in primary immune responses. D Switch from an alpha beta to a gamma delta T-cell receptor. E Express germ line Ig V genes.
Express high levels of CD44.
The single best defining feature of a regulatory T-cell is: A Expression of CD4 B Expression of Foxp3 C Production of IL-10 D That it can be induced by TGFβ E Expression of CD25
Expression of the Foxp3 transcription factor is currently the single best 'marker' that correlates with regulatory T-cell activity.
The single most effective agent at downregulating Th2 cells is: A Gamma interferon B IL-12 C Antigen D IL-2 E Th17 cells
Gamma interferon --> is a defining cytokine of Th1 cells and involved in their downregulation of Th2 cells.
Antibody titer refers to the: A Absolute amount of specific antibody. B Affinity of specific antibody. C Avidity of specific antibody. D Concentration of specific antibody. E Highest dilution of antibody still able to give a positive result in a test system.
Highest dilution of antibody still able to give a positive result in a test system.
Cell-mediated immunity: A Is unaffected by exercise. B Is unaffected by surgical trauma. C Is unaffected by diet. D May be grossly impaired by protein-calorie malnutrition. E Is unaffected by protein-calorie malnutrition.
May be grossly impaired by protein-calorie malnutrition.
The affinity of an antibody can be determined by measuring: A Its concentration. B The valency of antigen binding. C The amount of antibody bound at various antigen concentrations. D Its ability to neutralize bacterial toxins. E The sedimentation coefficient of the antibody.
The amount of antibody bound at various antigen concentrations.
Antigens in tissues can be localized with fluorescent antibodies using: A Flow cytofluorimetry. B A confocal fluorescence microscope. C Autoradiography. D An enzyme substrate. E The electron microscope.
A confocal fluorescence microscop → will clearly define the localization of antigens in tissues which have bound fluorescent antibody and the optics enable high resolution at high magnification.
A catalytic antibody is: A An enzyme used to digest antibody. B An immunoabsorbent. C Found in the vacuoles of phagocytic cells. D An antibody that is capable of acting as an enzyme. E An antibody to zymosan.
An antibody that is capable of acting as an enzyme.
Antigen-specific B-cells can be purified by: A Sedimentation rate. B Panning on anti-Ig plates. C Phagocytosis. D Forward light scatter in the fluorescence activated cell sorter (FACS). E Binding of fluorescent antigen and separation in the FACS.
Binding of fluorescent antigen and separation in the FACS. Antigen-specific B-cells would specifically bind the fluorescent antigen and provide a signal in the FACS which would be utilized to select these cells.
A gene can be selectively disrupted by: A Electroporation with the normal gene. B Homologous recombination. C Liposome transfection with the normal gene. D Antisense RNA. E X-Irradiation.
Homologous recombination → is a relatively rare event which involves interchange of a transfected genetic sequence with that of the homologous native gene and if one introduces an alteration in the reading frame, this will selectively disrupt gene expression.
In an ELISA you might use an antigen or antibody labeled with: A 125I B FITC C Colloidal gold D Europium 3+ E Horseradish peroxidase
Horseradish peroxidase Enzyme-linked immunosorbent assays (ELISA) use reagents that are labeled with enzymes which catalyse a color change in a substrate, e.g. horseradish peroxidase, alkaline phosphatase.
Common approach to generating conditional knockout mice involves using: A TdT. B Radiation chimeras. C ELISPOTS. D Tritiated thymidine. E LoxP.
LoxP DNA sequences form recognition structures for the Cre recombinase enzyme. The deletion of a functional gene, homologously replaced by the same gene flanked by loxP sequences, will be conditional on the cells additionally expressing a Cre transgene. Expression of the Cre transgene can be determined by linking it to a cell or tissue-specific promoter
Which of the following is not used for the precipitation of immune complexes? A Nephelometry. B Polyethylene glycol. C Ammonium sulfate. D Antibody to immunoglobulin. E Staphylococci.
Nephelometry is a method using low angle forward scattering of an incident light source to measure the cloudiness or turbidity caused by aggregated immune complexes.
Which one of the following events occurs earliest in T-cell signaling: A Activation of phospholipase C. B Activation of protein kinase C. C Production of inositol triphosphate. D Activation of protein tyrosine kinase. E Mobilization of intracellular calcium.
Activation of protein tyrosine kinase activity is responsible for subsequent activation of membrane components by phosphorylation.
Lipopolysaccharide (LPS) from Gram-negative bacteria is: A A thymus-dependent antigen. B A type 2 thymus-independent antigen. C A polyclonal activator of murine B-cells. D Cross-links Ig receptors on B-cells. E Produces high affinity IgG memory responses.
A polyclonal activator of murine B-cells. - LPS reacts with a specific receptor on most murine B-cells and therefore is not selective for B-cells of any particular antigen specificity.
In extreme antigen excess, immune complexes between IgG and a tetravalent antigen have the composition: A Ag1Ab4 B Ag4Ab3 C Ag2Ab1 D Ag3Ab2 E Ag2Ab7
Ag2Ab1
A HAMA response cannot be reduced or eliminated using: A ADEPT. B Chimeric antibodies. C Humanized antibodies. D Grafted CDRs. E Human antibodies.
ADEPT. Antibody-directed enzyme prodrug therapy is a sophisticated approach to the treatment of tumors, but does not itself reduce a HAMA response.
The early increase in phospholipase C gamma 1 activity following T-cell stimulation: A Represents a sensitive regulatory negative feedback control mechanism. B Dephosphorylates protein tyrosine kinase inhibitors. C Accelerates hydrolysis of diacylglycerol. D Accelerates hydrolysis of phosphatidylinositol diphosphate. E Accelerates hydrolysis of inositol triphosphate.
Accelerates hydrolysis of phosphatidylinositol diphosphate. - The enzyme splits phosphatidylinositol diphosphate to diacylglycerol and inositol triphosphate.
Which of the following is not used as a direct conjugate to the antibody for visualizing tissue antigens: A Fluorescein. B Anti-immunoglobulin. C Alkaline phosphatase. D Peroxidase. E Gold particles.
Anti-immunoglobulin --> used to detect the binding of antibody to tissue antigens, but can only be visualized by conjugation with an appropriate label.
A major factor regulating the adaptive immune response is: A The neutrophil. B Complement membrane attack complex. C C-reactive protein. D Antigen concentration. E Haptoglobin.
Antigen concentration.
The single most important factor controlling the B-cell response is: A Antibody concentration B Antigen concentration C Assistance from follicular dendritic cells D The interdigitating dendritic cell E Regulatory T-cells
Antigen drives both T-cell and B-cell responses.
Negative feedback on adaptive B-cell responses is mediated by: A Antigen specific IgM. B Antigen specific IgG. C Just antigen neutralization. D Fc gamma receptors on macrophages. E F(ab')2 anti-mu.
Antigen specific IgG.
Injection of a mouse with a very high dose of sheep erythrocytes induces: A A generalized antigen non-specific suppression. B Antigen-specific T-suppression. C Class switching to IgM antibody production. D IFN-gamma production by Th2 cells. E A high antibody response.
Antigen-specific T-suppression.
The TUNEL technique can be employed to measure: A Precursor frequency. B Apoptosis. C Directional migration of neutrophils. D Phagocytosis. E Surface exposed phosphatidylserine.
Apoptosis. TdT-mediated dUTP nick end labeling utilizes terminal deoxynucleotidyl transferase to add labeled nucleotides to the 3' ends of the DNA fragments that result from internucleosomal cleavage during apoptosis.
An example of an anti-apoptotic molecule is: A Bcl-2. B TRAIL. C Bax. D FADD. E Caspase 8.
Bcl-2 Molecules such as bcl-2 and bcl-XL prevent the release of pro-apoptotic proteins from mitochondria. Note, however, that some members of the bcl-2 family, such as bid, have pro-apoptotic functions.
A single chain Fv fragment (scFv) will: A Fix C1q. B Bear idiotypes. C Cross-link antigen. D Only be present on the surface of filamentous bacteriophage. E Possess either VH or VL but not both.
Bear idiotypes. --> variable region-associated antigenic determinants.
B-cells are distinct from T-cells: A Are polyclonally activated by phytohemagglutinin. B Bear surface Ig receptors for antigen. C Bear surface CD3 molecules. D Are lymphocytes. E Can be activated by stimulation through the antigen receptor alone.
Bear surface Ig receptors for antigen. - The specific receptor for antigen on B-cells is surface immunoglobulin whereas that on T-cells is the alpha-beta or gamma-delta TCR.
When a resting naive T-cell engages its specific MHC/peptide complex displayed on the surface of a fibroblast it: A Undergoes blast cell formation. B Produces IL-2. C Moves from Go to G1 of the cell cycle. D Becomes anergic. E Secretes IL-1.
Becomes anergic - In the absence of costimulator, a cell becomes anergic and incapable of subsequent response to the specific antigen.
The alpha beta heterodimeric form of the IL-2 receptor: A Is downregulated on activated cells. B Binds IL-2 with high affinity. C Is found only on T-cells. D Uses CD45 as an alpha chain. E Allows rapid dissociation of bound IL-2.
Binds IL-2 with high affinity. - The alpha beta heterodimeric form of the IL-2 receptor has an affinity (Kd) of 10-11 M (10 pm), whereas the alpha chain alone binds IL-2 with low affinity, and the beta chain alone with medium affinity.
CD4: A Is essentially an intracellular glycoprotein. B Is heterodimeric. C Binds processed peptide in its outer groove. D Binds to MHC class II on antigen-presenting cells. E Is highly polymorphic.
Binds to MHC class II on antigen-presenting cells. - CD4 binds to constant regions on the MHC class II.
A confocal microscope at high magnification does not: A Bring all focal planes of an image into focus simultaneously. B Permit construction of a 3-dimensional image. C Improve the quality of image definition in a single plane. D Provide quantitative data. E Function with fluorescent conjugates.
Bring all focal planes of an image into focus simultaneously.
Cytokines always act: A By binding to specific receptors. B In an autocrine fashion. C At long range. D Antagonistically with other cytokines. E Synergistically with other cytokines.
By binding to specific receptors. - The cell-type specificity of cytokines is provided by the regulated expression of specific cytokine receptor genes. Many cytokine receptors consist of more than one polypeptide. For example, the IL-2 receptor is composed of an alpha chain (CD25) of low affinity and a beta chain of intermediate affinity; when both are expressed together they form the high affinity IL-2 receptor.
Effector memory T-cells can be distinguished from the central memory T-cells from which they arise by: A Their life-span. B CD45RA. C CCR7. D CD3. E IL-4 secretion.
CCR7
The T-cell ligand binding B7 on a professional antigen-presenting cell is: A CD28 B CD2 C LFA-1 D ICAM-1 E VCAM-1
CD28 - An alternative ligand for B7, present on activated T-cells, is CTLA-4.
The main costimulatory signal for activation of resting T-cells is provided by ligation of: A CD28 B Surface Ig C LFA-1 D VLA-4 E IL-2
CD28 - B7 (CD80 and CD86) on the antigen-presenting cell ligating CD28 on the T-cell provides the main costimulatory signal for the activation of resting T-cells.
The T-cell receptor link to MHC/peptide is enhanced by interaction between MHC class II on the antigen-presenting cells with the following molecule on the T-cell: A LFA-1 B CD2 C CD4 D CD8 E CD28
CD4 - CD4 on helper T-cells binds to the non-polymorphic part of the MHC class II molecule.
In the germinal center, B-cells become memory cells under the influence of: A CD40 B CD23 C IL-1 alpha D IL-4 E TGF beta
CD40 Engagement of CD40 by T-cell CD40L (CD154) drives the cell to the memory compartment.
T-cell CD40L provides a costimulatory signal to B-cells by ligating: A Surface Ig B MHC class II C CD28 D CD19 E CD40
CD40 - The costimulatory signal provided by the CD40L/CD40 interaction is necessary for the activation of resting B-cells by helper T-cells. Note that CD40L is the abbreviation for CD40 ligand, which is also known as CD154.
Activation of resting B-cells by T-helpers depends directly upon costimulatory interaction between: A CD40 and CD40L. B B7 and CD28. C B7 and CTLA-4. D CD4 and MHC class II. E ICAM-1 and LFA-1
CD40 and CD40L.
Which of the following is never related to poor MHC-linked immune response: A Defective T-cell repertoire. B T-suppression. C Inadequate antigen processing. D Poor binding of peptide epitope to MHC. E Defective V gene rearrangement.
Defective V gene rearrangement. Rearrangements in the VDJ segments of the T-cell receptor prior to thymic education are not related to the MHC genotype.
High antibody responses linked to MHC class II genes: A Are independent of MHC haplotype. B Depend on good T-helper cell recognition of class II/antigen peptide complex. C Depend on defective antigen presentation by MHC molecules. D Result from tolerance to MHC/self-peptide complexes. E Require suppression of Th2 cells.
Depend on good T-helper cell recognition of class II/antigen peptide complex.
T-cell help for antibody production: A Depends on T-cell recognition of native antigen bound to B-cell surface Ig. B Depends on T-cell recognition of antigen processed by the B-cell. C Involves class I MHC on the B-cell. D Can occur in X-irradiated mice. E Is a feature of the antibody response to pneumococcal polysaccharide SIII.
Depends on T-cell recognition of antigen processed by the B-cell. - The native antigen binds to B-cell surface Ig, is taken inside the cell, processed and the peptide placed as a complex with class II MHC on the cell surface where it is recognized by T-helper cells.
A high antibody response to an antigen such as (TG)-A-L in a given mouse strain: A Is linked to immunoglobulin gene polymorphism. B Is independent of MHC (H-2) haplotype. C Depends on T-cell recognition of the antigen bound to MHC class II . D Depends on T-cell recognition of the antigen bound to MHC class I. E Reflects a general propensity to make high titer antibody responses.
Depends on T-cell recognition of the antigen bound to MHC class II
Immune responses are: A Depressed by stress. B Stimulated by glucocorticoids. C Depressed by estrogens. D Stimulated by androgens. E Depressed by growth hormone.
Depressed by stress. Stress induces glucocorticoids which are immunosuppressive.
A Cytokine receptor which is a member of the hematopoietin receptor family is: A IL-8 receptor. B IFN gamma receptor. C TNF (TNF-alpha) receptor. D IL-1 receptor. E IL-2 receptor.
IL-2 receptor. - The hematopoietin receptor family contains a large number of members each of which comprises one or two polypeptide chains responsible for cytokine binding and an additional shared (common) chain involved in signal transduction.
The cytokine which is most involved in the class switch to IgE production is: A IL-1 B IL-2 C TGF beta D IL-4 E IL-5
IL-4
Which of the following is characteristically produced by the Th2 CD4 cells which provide help for antibody production, but not by Th1 cells?: A IFN-gamma B Lymphotoxin (TNF-beta) C GM-CSF D IL-4 E IL-1
IL-4, together with IL-5, IL-6, IL-10 (mouse only) and IL-13 is characteristically produced by Th2 cells.
Which one of the following cytokines can mediate release of acute phase proteins from the liver?: A IL-10. B TGF beta. C IL-6. D IL-12. E IL-8.
IL-6, like IL-1, can mediate release of acute phase proteins from the liver which suggests that, unlike most cytokines, they do not function only as short range mediators.
The RAST measures: A Antigen concentration. B IgE antibodies. C IgM antibodies. D Agglutination. E IgG antibodies.
IgE antibodies. The radioallergosorbent test (RAST) specifically measures IgE antibodies in allergic patients. The allergen, for example pollen extract, is covalently coupled to a paper disc which is then treated with patient's serum. The amount of specific IgE bound is determined using labeled anti-IgE.
Prior to class switching, B-cells express: A IgA alone B IgA and IgG C IgM and IgD D IgD alone E No surface Ig
IgM and IgD Differential splicing allows coexpression of IgM and IgD with identical V regions on a single cell. IgD is lost upon antigen stimulation so that memory B-cells lack this class of immunoglobulin.
IgG antibodies: A Are the earliest class to appear in an immune response. B Are normally dimeric in mucosal secretions. C Remain of low affinity. D Inhibit antibody responses through the Fc gamma receptor FcgRIIB1 on B-cells. E Augment antibody responses through the Fc gamma receptor FcgRIIB1 on B-cells.
Inhibit antibody responses through the Fc gamma receptor FcgRIIB1 on B- cells.
Which of the following is not a feature of germinal center B-cells: A Immunoglobulin gene class switching. B Apoptosis. C Initial VDJ rearrangement. D Somatic hypermutation. E Proliferation.
Initial VDJ rearrangement.
Suppression of Th2 by Th1 cells may be mediated by: A IL-1. B IL-3. C IL-4. D GM-CSF. E Interferon-gamma.
Interferon-gamma.
Th1 cells secrete: A CD4. B IL-4. C IL-5. D IL-6. E Interferon-gamma.
Interferon-gamma.
The use of green fluorescent protein in flow cytofluorimetry permits measurement of: A Cell size. B Cell granularity. C Antibody secretion. D DNA content. E Intracellular gene expression.
Intracellular gene expression.
Antigenic competition: A Involves competition between T-cell epitopes for the MHC groove. B Involves competition for available soluble antibodies. C Is unrelated to the concept of dominant and subdominant epitopes. D Can only occur with cryptic epitopes. E Refers to the differential immunogenicity of the carbohydrate and protein moieties in a glycoprotein.
Involves competition between T-cell epitopes for the MHC groove.
Sos (Son of sevenless): A Itself directly activates MAP kinase kinase kinase. B Recruits the Grb2 adaptor protein. C Is a guanine nucleotide exchange factor. D Is a GTPase-activating protein. E Is phosphorylated by Mek.
Is a guanine nucleotide exchange factor. - Sos is a guanine nucleotide exchange factor (GEF) which promotes the conversion of Ras-GDP to Ras-GTP.
A T-cell hybridoma A Is obtained by continuous culture of T-cells with antigen. B Is obtained by cloning antigen-specific splenic T-cells. C Is obtained by fusing T-cells with a T-cell tumor cell line and cloning. D Expresses a multiplicity of T-cell receptor specificities. E Results from producing a mouse which is transgenic for the rearranged alpha- and beta-receptor from a T-cell clone
Is obtained by fusing T-cells with a T-cell tumor cell line and cloning.
The level of antigen: A Is unrelated to the intensity of the immune response. B Is related to the intensity of the immune response. C Never has an effect on the response to a T-independent antigen. D Has no effect on the concentration of MHC bound processed antigen. E Is constant in the extracellular fluid.
Is related to the intensity of the immune response.
Proliferation of activated T-cells: A Is stimulated by a single signal induced by engagement of the T-cell receptor. B Requires both the signal described in A plus costimulation from B7. C Requires both the 2 signals described in B plus interaction between LFA-1 and ICAM-1. D Requires only mutual binding of LFA-3 and CD2 on the antigen-presenting cell and T-cell respectively. E Is unaffected by anergy.
Is stimulated by a single signal induced by engagement of the T-cell receptor. - Unlike naive T-cells, activated T-cells only require a single signal induced by engagement of the T-cell receptor with MHC/peptide and involvement of CD4 or CD8 recognizing the constant part of the MHC.
An internal image monoclonal anti-idiotype: A Has specificity for its own internal structure. B Is the mirror image of the idiotype. C Has identical idiotypes on heavy and light chains . D Mimics a single epitope on the antigen. E Cannot function as a 'surrogate' antigen.
Mimics a single epitope on the antigen because it reacts with the antigen-binding site which itself reacts with a single epitope.
Protein-calorie malnutrition does not affect: A Lymphoid tissue. B The level of circulating CD4 T-cells. C Cell-mediated immunity. D The affinity of antibody responses. E Phagocytosis of bacteria.
Phagocytosis of bacteria.
The activation of lymphocytes cannot be assessed by: A Mitosis. B Cytokine release. C Phagocytosis. D Cytotoxicity. E Limiting dilution analysis.
Phagocytosis. (Lymphocytes are not phagocytic, irrespective of their activation status.)
Protein tyrosine kinase activity following T-cell stimulation: A Phosphorylates and thereby activates phospholipase C gamma 1. B Is an inherent property of the T-cell receptor alpha and beta chains. C Is an inherent property of CD3. D Is unaffected by herbimycin A. E Is unrelated to phosphorylation of the CD3-associated zeta chains.
Phosphorylates and thereby activates phospholipase C gamma 1. - The tyrosine kinase activates the phospholipase, which accelerates the hydrolysis of phosphatidylinositol 4,5-diphosphate to diacylglycerol and inositol 1,4,5-triphosphate.
Low amounts of antigen: A Produce low affinity antibodies. B Do not influence the affinity of antibodies. C Produce high affinity antibodies. D Affect the avidity but not the affinity of antibodies. E Preferentially induce class switching.
Produce high affinity antibodies.
High responder 'Biozzi' mice: A Phagocytose carbon particles faster than low responders. B Were obtained by breeding wild mice through 5 generations, selectively mating the high responders each time. C Differ from low responders by a single gene . D Produce high titer antibodies to only a very restricted number of antigens. E Produce high titer antibodies to a variety of antigens.
Produce high titer antibodies to a variety of antigens.
Western blots are primarily used to detect: A Protein. B Carbohydrate. C Lipid. D RNA. E DNA.
Protein. Following separation by techniques such as SDS-PAGE or isoelectric focusing, proteins can be blotted by transverse electrophoresis onto polyvinylidene difluoride (PVDF) or nitrocellulose membranes and then identified by staining with appropriately labeled antibodies.
Stimulation of glucocorticoid synthesis by IL-1: A Provides a basis for a feedback suppressor circuit. B Cannot provide a basis for a feedback suppressor circuit. C Augments IL-1 synthesis. D Augments cell-mediated immunity. E Augments IFN-gamma synthesis.
Provides a basis for a feedback suppressor circuit. Glucocorticoids can act as a negative feedback because they suppress immune responses and suppress the production of interleukin-1.
The stress induced by severe exercise can increase susceptibility to infection by: A Raising plasma levels of cortisol. B Increasing lymph flow. C Increasing synthesis of adrenaline. D Damaging mast cells. E Increasing the respiratory rate.
Raising plasma levels of cortisol.
Cross-linking of B-cell surface receptors: A Is a characteristic feature of thymus-dependent antigens. B Lowers the intracellular Ca++ concentration. C Rapidly phosphorylates the Ig-alpha and Ig-beta chains of the surface Ig receptor. D Requires contiguity of 2 B-cell epitopes of different specificity on the same antigen molecule. E Cannot be achieved by anti-idiotypic antibodies.
Rapidly phosphorylates the Ig-alpha and Ig-beta chains of the surface Ig receptor. - Within one minute of surface Ig ligation there is rapid phosphorylation of the Ig-alpha and Ig-beta chains and a subsequent rise in intracellular calcium.
Surface plasmon resonance is a system based on: A Fluorescence. B Radioactivity. C Reflected light. D Molecular resonance. E Magnetic fields.
Reflected light Monoclonal antibody is coupled to dextran which overlays a gold film on a glass prism sensor chip. Antigen present in a pulse of fluid will bind the sensor chip and, by increasing the amount of protein, will alter the angle of reflection of light. The system provides data on the kinetics of association and dissociation.
T-cell mutants lacking CD45 cannot transduce signals received through the specific T-cell receptor because CD45: A Has protein tyrosine kinase activity. B Directly phosphorylates CD4. C Is a calcium ion channel. D Removes a phosphate group from a negative regulatory site on the Lck kinase. E Acts as a nuclear transcription factor.
Removes a phosphate group from a negative regulatory site on the Lck kinase. - In the CD45 deficient cells, the Lck is phosphorylated on tyrosine 505, a negative regulatory site for kinase activity.
HAT medium is used to: A Immortalize B-lymphocytes. B Culture B-lymphocytes. C Select for hybrids in the hybridoma technique. D Kill B-cell hybridomas. E Fuse B-lymphocytes to myeloma cells.
Select for hybrids in the hybridoma technique.
SDS-PAGE separates proteins on the basis of: A Isoelectric point. B Sedimentation coefficient. C Amino acid sequence. D Degree of glycosylation. E Size.
Size.
High affinity B-cell clones in mammals are usually generated by: A Somatic hypermutation. B Expression of high affinity precursors in the virgin (naive) B-cell population. C Class switching. D Apoptosis. E Gene conversion.
Somatic hypermutation. Class-switched B-cells are subject to high mutation rates after the initial response. The normal V region mutation rate is of the order of 10-5/base pair/cell division but this rises to 10-3 in B-cells as a result of antigenic stimulation. Randomly, some of the mutated daughter cells will have higher affinity for antigen, some the same and some lower. B-cells expressing antibody of increased affinity will be preferentially selected by antigen.
The specificity of antibody secreted by a B-cell may not be the same as that of the surface Ig of the clonal parent because of: A Class switching. B Somatic hypermutation. C Allelic exclusion. D Alternative splicing. E Different heavy:light pairing.
Somatic hypermutation. the specificity of antibody secreted by daughter cells is initially the same as that of the clonal parent, but later may deviate to some extent due to the high frequency of mutation as the clone expands.
The carrier T-cell epitope on a thymus-dependent antigen: A Behaves like a hapten. B Needs to be polymeric. C Need not be physically connected to the B-cell epitope. D Is a carbohydrate. E Stimulates help for the B-cell response.
Stimulates help for the B-cell response. - The presentation of the T-cell epitope by the B-cell recruits the T-cell help for activating the B-cell causing its proliferation and final maturation.
The following is characteristic of B- but not T-cells: A Class I MHC. B CD3. C Measles virus receptor. D Polyclonal activation by concanavalin A. E Surface immunoglobulin.
Surface immunoglobulin.
The nuclear AP-1 site responsible for 90% of IL-2 enhancer activity binds: A The Oct - 1 transcriptional factor. B The Fos/Jun transcription factors. C The nuclear factor of activated T-cells (NFAT). D The NF-kappa B transcriptional factor. E Polyclonal mitogenic agents such as concanavalin A.
The Fos/Jun transcription factors. - The MAP kinase JNK phosphorylates Jun, which then binds as a binary complex with Fos to the AP-1 site.
In the immunological synapse: A The acetylcholine receptor in expressed on the T-cell. B Production of substance P by the antigen-presenting cell is a key event. C The initial interaction between TCR and MHC is unstable. D Adhesion molecule pairs eventually move to the center of the synapse. E The B7-CD28 interaction is redundant.
The initial interaction between TCR and MHC is unstable. - One of the main functions of the immunological synapse is thought to be to cement the initially unstable interactions between TCR and MHC in order that optimal activation of the T-cell can occur.
The functional activity of neutrophils can be assessed by: A The nitroblue tetrazolium test. B Proliferation. C Limiting dilution analysis. D A plaque test for antibody. E A fluorescent antibody test for myeloperoxidase.
The nitroblue tetrazolium test. Phagocytosis activates a respiratory burst, which reduces nitroblue tetrazolium into blue formazan.
On injection into mice, bovine serum albumin conjugated with dinitrophenol (DNP) behaves as a: A Type 1 thymus-independent antigen. B Type 2 thymus-independent antigen. C Thymus-dependent antigen. D A polyclonal T-cell activator. E Hapten.
Thymus-dependent antigen. - BSA-DNP is thymus-dependent in that the BSA acts as a T-dependent carrier which is processed by an anti-DNP B-cell which binds the conjugate and presents the processed peptide with MHC class II to the T-helper cell. The T-cell helps the B-cell to mature into an anti-DNP clone.
IFN-gamma and TNF (TNF alpha) can act synergistically: A To downregulate expression of MHC class I. B Because IFN-gamma downregulates expression of TNF receptors. C To upregulate expression of MHC class II. D Because they both bind to the same receptor. E Because they cross-link IFN-gamma and TNF beta receptors.
To upregulate expression of MHC class II. - There is synergism between IFN-gamma and TNF in the upregulation of surface MHC class II molecules on, for example, cultured pancreatic insulin- secreting beta cells.
Introduction of a gene into a cell using calcium phosphate precipitate is termed: A Electroporation. B Homologous recombination. C Biolistics. D Transfection. E Mutation.
Transfection → is the introduction of a gene into a cell; calcium phosphate precipitate is one method of achieving this
Human monoclonal antibodies can be obtained: A Using Epstein-Barr virus immortalization of T-cells. B Easily from human hybridomas selected with HT medium. C Using transgenic xenomouse strains. D By a single point mutation of a mouse monoclonal antibody. E Only by fusing human B-cells with mouse myeloma cells.
Using transgenic xenomouse strains.
The association constant (Ka) at equilibrium is represented by: A [AgAb complex] B [free Ag][free Ab] C [free Ag][free Ab]/[AgAb complex] D [AgAb complex]/[free Ag][free Ab] E [free Ag]/[free Ab]
[AgAb complex]/[free Ag][free Ab]
Which is the first of the following genes to be upregulated subsequent to T-cell activation: A Transferrin receptor B Cytokine receptor C Cytokine D c-myc E VLA-1
c-myc - Within 15-30 min c-myc, together with transcription factors involved in the control of IL-2 expression such as NFAT and Fos/Jun, are expressed. A complex series of tyrosine and serine/threonine phosphorylation reactions produce the factors which push the cell into the mitotic cycle and drive clonal proliferation.
Coating a cell with specific antibody facilitates its selection by: A Sedimentation rate. B Buoyant density. C Adherence to plastic surfaces. D Magnetic beads coated with anti-Ig. E Light scatter in the fluorescence activated cell sorter (FACS).
magnetic beads coated with anti-immunoglobulin will bind to the cells which are coated on their surface with antibody and these can then be separated with a magnet.