Formative Quiz Review 1 Flashcards
A 4-year-old child is referred to you with the diagnosis of leukocyte adhesion defect. She has a history of recurrent bacterial infections, including pneumonias and skin abscesses. Radiography demonstrates granuloma-like lesions in her lungs and liver. However, the data in Table 1 suggests this condition has not been properly diagnosed. Which one of the following elements of these data is INCONSISTENT with a diagnosis of LAD?
CD2 values
CD19 values
CD18 values
CD4 values
CD3 values
CD 18 values - C. Correct. Leukocyte adhesion defect is an absence of LFA-1, CR3 and CR4. CD11a is a component of one of these receptors (LFA-1) and its expression is altered in these patients. CD11a pairs with CD18 to form the LFA-1 receptor. Because the actual defect in LAD is the absence of CD18, any receptor that uses CD18 would be absent from LAD cells. In this patient, the normal numbers of CD18-positive cells also indicate that she has been misdiagnosed.
A patient arrives at a clinic with a number of boils on his back, and a sample of pus from one of the lesions was sent to the laboratory for culture. The microbiology laboratory cultures heavy growth of Staphylococcus aureus, a gram-positive bacterium. Which of the following innate immune components is probably NOT involved in the protective response to this pathogen?
C5a
C3b
Superoxide
Lysozyme
TLR4
TLR 4 - LPS is not present in gram-positive bacteria.
The cartoon of the portly mouse below depicts the vascular and lymphatic systems, showing a T cell that will travel through both duct systems. Which of the following best represents the path taken by a naïve T cell?
Aorta, Heart, Lung, Lymphatic vessel, Gut, Lymph node, Aorta
Aorta, Spleen, Heart, Aorta, Lymph node, Lymphatic vessel, Heart, Lung, Aorta
The T cell is most likely to remain in the blood stream only, as there is no antigenic challenge.
Aorta, spleen OR lymph node; the T cell will remain at one of these secondary lymphoid structures until it encounters antigen.
Aorta, Spleen, Heart, Aorta, Lymph node, Lymphatic vessel, Heart, Lung, Aorta - T cells travel through the blood stream to gain access to the secondary lymphoid structures, where they reside and ‘travel’ for a short time in search of antigen. If they do not encounter antigen (Question 4) within the lymphoid structure they exit via the draining veins (spleen) or efferent lymphatic ducts (lymph nodes), recirculate by making their way back to the heart where they begin their journey once again.
The neutrophils (N) in the accompanying photomicrograph are attracted to their extravascular location primarily by which one of the following factors?
C3a
C5a
C5b
Collagen
Fibrin
Neutrophil chemotactic factor
C5a - Neutrophils follow a gradient formed by complement factor C5a to the site of injury. Other factors may also be involved, including certain bacterial peptides, but C5a is the most widely known and understood
TAP is a component of which MHC pathway?
MHC class I pathway
Polymorphisms in HLA-A are most likely to influence the affinity of the interaction between which of the following pairs:
HLA-A and anchor residues
HLA and ß2m
HLA-A and CD8
HLA-A and chaperones
HLA and TAP
HLA-A and anchor residues - polymorphisms in HLA influence the ability of HLA to bind peptides and the TCR. The amino acids of the peptides that associate with HLA are called anchor residues.
You are characterizing the macrophage response to the bacterium Pseudomonas aeruoginosa. Knowing that this gram-negative bacterium has a potent endotoxin, you decide to determine if IL-1 transcription is activated by the pathogen through a Toll-like receptor. Which of the following signaling intermediates is involved in this pathway?
IκB
NFAT
NOD
PLCγ
Stat-1
IkB
Which one of the following is a “pattern recognition receptor” of the innate immune system that can distinguish host and microbial structures?
- Fc receptor
- Complement receptor 3 (CR3)
- Toll-like receptor 9 (TLR9)
- α-defensin
- BCR
Toll-like receptor 9 - Correct. Toll-like receptors are good examples of receptors capable of recognizing molecular patterns on microbes and distinguishing them form host structures.
Which one of the following processes contributes most to the increase in affinity of an antibody response over time (affinity maturation), especially following multiple immunizations?
Somatic hypermutation
BCR editing
Ig class switching
Joining of V, D and J segments in memory B cells
Activation of Th1 cells
Somatic hypermutation - Affinity maturation is the process by which an animal’s antibody response over time acquires a higher average affinity. This results from the selective activation of B cells that bear antigen receptors (BCR) with high affinity for the immunizing antigen. Somatic hypermutation occurs during memory B cell development and generates mutated BCR, some with much higher affinities for the antigen.
Recently, a patient was described who had a defect in TLR4-initiated cell signaling. Which of the following groups of microbes would be expected to cause recurrent infections in this patient?
Respiratory viruses
Fungi that cause vaginal yeast infections
Gram-negative bacteria
Gram-positive bacteria
Insect vector-borne parasites
Gram-negative bacteria - Toll-like receptor 4 (TLR4) is a member of receptors that recognize conserved microbial components and initiate innate immune responses. TLR4 is a specific signaling receptor for the lipopolysaccharides (LPS) found on gram-negative bacteria. It is not known to bind to fungal, viral or parasitic ligand.
Which one of the following properties would distinguish (be different between) IgG and IgM antibody molecules?
Their ability to activate complement
Their ability to bind to human mast cell Fc receptors
Their presence of κ light chains
Their ability to cross the placenta
Their ability to precipitate soluble antigens
Only human IgG can cross the placenta; IgM cannot.
Which one of the following properties of the complement system requires the terminal components, including C9?
Chemotaxis
Inflammation
Membrane attack (lysis)
Opsonization
Recognitition of microbes
Membrane attack - lysis
Which one of the following cytotoxic cells is most active against host cells that DO NOT express MHC class I molecules?
Cytotoxic T cells
Natural killer cells
Natural killer T cells
Neutrophil
Macrophage
NK cells bear an inhibitory receptor for MHC class I molecules that keeps the NK cells quiescent in the presence of class I molecules. In cells that lack class I expression (e.g., tumor cells or virus-infected cells), the inhibitory receptor is not engaged allowing the NK cell to become activated.
An immune-deficient patient is diagnosed with a congenital defect in RAG-2 expression. Which
of the following observations would MOST LIKELY be seen in this patient?
Aberrant B cell development in the thymus
A lack of peripheral B cells, T cells, and NK cells
An absence of double positive and single positive thymocytes
Normal peripheral B cell numbers and a lack of CD4+ T cells
Normal peripheral CD4+ T cell numbers and a lack of B cells
An absence of double positive and single positive thymocytes - RAG is required for the rearrangement of genes that encode the BCR and TCR. Cells of the B and T cell lineages dependent on expression of a pre-BCR or pre-TCR would be absent or extremely low. This includes any cell beyond the pre-B stage or the DN stage.
In which of the following infectious diseases is a Th1 pattern of cytokine production the most beneficial?
E. coli urinary tract infections
Tuberculosis
Streptococcal pneumonia
Pseudomonas-associated sepsis
Staphylococcal skin infections
Tuberculosis - Th1 cytokines, such as IFN-g, are important against intracellular bacterial pathogens, such as M. tuberculosis, the causative agent of tuberculosis. IFN-g serves to activate infected macrophages for bacteriocydal activity.
Mixed lymphocyte reaction does what?
C. The MLR is used to measure HLA incompatibility between two individuals.
Approximately how many Ig gene segments are required to produce antibodies with 1 billion different specificities?
1 billion
1 million
10
100 million
100
100
VLA-4 binds?
VCAM-1
The image below depicts a portion of the Peyer’s Patches of the small intestine. Match the following functions with the letters that appear in the photomicrograph. Note that for clarity, some duplicate structures are labeled with the same letters. The location of the cells responsible for initial antigen uptake is:
D - villi
ABO blood antigens are:
Carbohydrates
Anaergy is a form of central or peripheral tolerance?
Both Central and Peripheral
What is the role of CR3?
The CR3 receptor binds Ag-Ab-iC3b complexes, and CR3 and CR4 are expressed on neutrophils and monocytes,
The ligand for this cell surface receptor requires TAP for its expression. Which of the following is the cell surface receptor?
CD3
CD8
CD18
CD19
CD154
CD8 - CD8 binds to MHC class I molecules, which require the transporter of antigenic peptides (TAP) for their expression.
Which of the following processes contributes the most to the size of the repertoire of T cell antigen receptors of an individual?
DNA recombination
Large pools of V region genes
Somatic hypermutation
Polymorphism
Active immunization
DNA recombination - Recombination of the V, D, and J regions accounts leads to the production of 10^9 unique B and T cell clones.
At which one of the following stages of B cell differentiation does Bruton’s tyrosine kinase (Btk) first play an essential role?
Plasma cell
Memory B cell
Mature B cell
Immature B cell
Pre-B cell
Pre-B cell - Precursor (Pre-) B cells are the first step in the B cell lineage that requires Btk for their maturation. This is evidence by deleting the gene in experimental animals or by studying XLA patients who lack a functional Btk. They do not show B cell lymphopoiesis beyond the pre-B cell stage.
An analysis of the blood lymphocyte subsets of an adult individual with a defect in his cell-mediated immunity was performed. Which one of the flow cytometry results shown in the figure below is consistent with a TAP deficiency in this patient?
D - This is a normal pattern for blood lymphocytes, except for the absence of CD8+ T cells. With a TAP deficiency, the patient does not express MHC class I molecules and does not develop the CD8+ subset because of the lack of positive selection in the thymus.
Which of the following is a mechanism that regulates the size of the MHC class I repertoire within an individual:
Vd.J recombination
Each cell expresses two allelic forms of MHC class I
Forming dimers with different combinations of a and b genes
Somatic hypermutation of MHC class I genes
Different cell types express different allelic forms of MHC class I
Each cell expresses two allelic forms of MHC class I
Inducible Cox-2 activity functions in a pro-inflammatory pathway by?
catalyzing prostanoid production in fibroblasts and macrophages
Which of the following is one of the most common causes of neutrophilia?
Parasitic infections
Chemotherapy for cancer
Bacterial infections
HIV/AIDS
Exposure to ionizing radiation
Bacterial infections - Elevated WBC counts should always suggest an infection. Parasitic infections more often induce eosinophilia; chemotherapy generally produces neutrophenia; HIV results in lymphopenia; and radiation exposure can cause pancytopenia.
Cytotoxic T lymphocytes can use multiple mechanisms to kill target cells. These include:
Expression of Fas ligand and release of granzymes.
Detection of loss of MHCII from the cell surface.
Detection of loss of MHCI from the cell surface.
Production of reactive oxygen and nitrogen intermediates.
Generation of complement, and hydrolases that can attack and destroy cells.
Expression of Fas ligand and release of granzymes.
Which one of the following is an immune evasion property of encapsulated bacteria, such as the pneumococcus?
Resistance to antibody binding
Resistance to antimicrobial peptides
Resistance to complement activation
Resistance to phagocytosis
Resistance to oxidants
Resistance to phagocytosis
Which one of the following is a property of peptides presented on MHC class II molecules?
They maintain their native conformation.
They are generated by proteasomes.
They bind β2-microglobulin.
They are derived from extracellular proteins.
They are transported by TAP.
They are derived from extracellular proteins. - Peptide antigens that bind to the class II MHC molecules are processed through the exogenous class II pathway by which extracellullar proteins are internalized within endosomes within the antigen-presenting cell.
Figure #1 illustrates a family pedigree in which HLA genotypes are shown. Which of the five children shown here is the child of a previous marriage involving the mother?
Daughter 2 - This daughter has apparently inherited her A1+ B32 haplotype from her mother. That leaves A1 + B3 from her biological father, which is not a haplotype she could have received from the father that is shown here. Thus, her genetic father is not shown and she is therefore a daughter of a previous marriage with the mother shown here.
With which of the following regions of MHC molecules can the T cell receptor on CD8+ T cells
interact?
α1 and α2
α1 and β1
α1 and β2m
α2 and α3
α2 and β2m
α1 and α2
A mouse is injected with an antigen that elicits an immune response that is characterized by a predominance of IgM production, no somatic hypermutation, and no memory formation. Which of the following properties MOST likely characterizes the antigen?
The antigen can be presented by MHC class II.
The antigen can bind both BCRs and TLRs.
The antigen can induce cell-mediated immunity.
The antigen can induce IL-13 production.
The antigen can inhibit Th17 differentiation.
The antigen can bind both BCRs and TLRs. - An antigen that induces an immune response with these characteristics is most likely a T-independent antigen. TI antigens are patterns and can also activate pattern recognition receptors, such as TLRs.
From analysis of the accompanying high power photograph, how would you classify the acute inflammatory exudates seen?
Eosinophilic
Fibrinous
Fibrous
Granulomatous
Purulent
Purulent - The photomicrograph shows an abundance of neutrophils (N). By definition, this is a purulent or suppurative exudate. This is the typical pattern of acute inflammation when the inciting stimulus is a pyogenic (pus forming) bacterial infection.
Which of the following is a mechanism that determines the size of the MHC class I repertoire within an individual?
Different cell types express different allelic forms of MHC class I
Each cell expresses two allelic forms of MHC class I in a codominant fashion
Forming dimers with different combinations of α and β genes
Somatic hypermutation of MHC class I genes
Vd.J recombination
Each cell expresses two allelic forms of MHC class I in a codominant fashion
Which of the following cells of the small intestine produces secretory component that is found in secretory IgA?
epithelial cells
Plasma cells are primarily responsible for which one of the following physiologic functions?
- Antibody production
- Collagen production
- Cytokine production
- Non-specific killing of invading bacteria
- Ingestion of dead or damaged tissue
Antibody production - Plasma cells are responsible for antibody production, which can result in the specific killing of bacteria. Non-specific killing is done by the neutrophils, via their myeloperoxidase system. Cytokines are largely produced by lymphocytes and macrophages.
The T cell antigen receptor signals through several intracellular biochemical pathways. Which of the following T cell receptor-mediated events is inhibited by cyclosporin?
The phosphorylation of IκB
The phosphorylation of ITAM motifs
The dephosphorylation of cytosolic NF-AT
The recruitment of ZAP-70
The phosphorylation of CD3ζ
The dephosphorylation of cytosolic NF-AT - NF-AT exists as a phosphorylated protein in the cytosol in resting cells. Cell activation results in the activation of a calcium/calmodulin-dependent phosphatase, called calcineurin, which dephosphorylates NF-AT. The dephosphorylated NF-AT can then move to the nucleus where it activates transcription. Cyclosporin blocks the activity of calcineurin and, therefore, blocks NF-AT-dependent transcription.
Mice have been genetically engineered so that they do not express the β2-microglobulin gene (β2-microglobulin knockouts). What effect would this mutation have on lymphocyte differentiation?
The mutants would not produce a population of CD4 CD8 thymocytes
The mutants would show reduced numbers of CD8 cells in their lymph nodes.
The mutants would have a phenotype similar to CD3 knockouts.
The mutants would have defective NK cell function.
The mutants would have defective Th1 cell function.
The mutants would show reduced numbers of CD8 cells in their lymph nodes. - The absence of β2-microglobulin would prevent MHC class I expression, which would prevent positive selection of single-positive CD8+ thymocytes. This would leave the animal without peripheral CD8+ T cells as well.
Does class switching occur in the T cell lineage?
NO
An otherwise healthy 26 year-old woman has a small laceration on her forearm. Microorganisms from the skin flora enter the wound and are captured by the Langerhans cells. Which of the following is the primary function of these Langerhans cells?
- Migrate to the cortex of the lymph node and present antigen to B cells via FcγR.
- Migrate to the paracortex of the lymph node and present antigens to T cells via MHC.
- Secrete IL-1 and induce the fever response.
- Secrete IL-4 and induce class-switch recombination.
- Release reactive oxygen species and destroy the pathogens.
Migrate to the paracortex of the lymph node and present antigens to T cells via MHC. - Langerhans cells are intradermal dendritic cells that present antigens to T cells. When activated by pathogens, Langerhans cells express chemokine receptors that induce migration into the T cell zone of lymph nodes.
Hematopoiesis is a process that is tightly regulated by cytokines. Which of the following cytokines regulates myelopoiesis, but not lymphopoiesis?
G-CSF
IL-2
IL-3
IL-7
IL-15
G-CSF
Neoplastic cells were prepared from a lymph node biopsy obtained from a patient with a lymphoma. The cells are analyzed by flow cytometry and the following phenotype is reported:
CD3: negative
CD19: positive
Intracellular Ig μ heavy chain: positive
Intracellular Ig κ and λ light chains: negative
From which of the following stages of lymphocyte development is this tumor most likely derived?
Pre-B cells - This phenotype indicates the B lymphoma cells were derived from pre-B cells, which express heavy mu chains, but no light chain. CD19 is a pan marker for B cells.
A 35-year-old man with a history of abdominal pain associated with edema affecting the bowel wall presents with an acute onset of nonpruritic facial edema. He has no history of allergies, and skin tests in the past have always failed to detect atopic allergies. Analysis of his serum complement shows decreased C2 and C4. Of the following treatments, which is the most appropriate for his current condition?
Recombinant IL-2
Recombinant C4
Recombinant C1 Inhibitor
Anti-IgE
Epinephrine
Recombinant C1 inhibitor - Giving more complement components may exacerbate this patient’s condition. The absence of hives and positive skin tests suggests that IgE antibody is not involved, do epinephrine is not likely to be beneficial. The condition is consistent with HAE, a condition we treat with recombinant C1 Inh.
Which of the following complement components inactivates the C3 convertase without altering the ability of C3 peptides to act as opsonins?
C3a inactivator
Factor I
Factor B
C1 inhibitor
Factor D
Factor I - Factor I converts C3b and C4b into iC3b and iC4b, respectively. These inactivated peptides retain the ability to bind CR3, but no longer can form C3 or C5 convertases.
Parents of a lost child arrive at mall security in a panic. At the same time, five lost children arrive at mall security. The security officer performs a quick blood test to determine which child belongs with these parents. Which of the following children are most likely these parent’s child?
HLA-A2, A4, HLA-B8, B1, HLA-DR2, DR3
HLA-A2, A4, HLA-B2, B1, HLA-DR3, DR1
HLA-A2, A5, HLA-B8, B2, HLA-DR2, DR6
HLA-A4, A10, HLA-B8, B1, HLA-DR1, DR3
HLA-A2, A5, HLA-B8, B2, HLA-DR2, DR1
HLA-A2, A4, HLA-B8, B1, HLA-DR2, DR3
A patient is diagnosed with a deficiency in the expression of the CD18 integrin. Which one of the following would you expect to be abnormal in this patient?
Binding of iC3b by neutrophils
Activation of the alternative pathway of complement
Production of TNF-α by macrophages in response to LPS
Activation of macrophages by IFN-γ
Activation of B cells in response to protein antigens
Binding of iC3b by neutrophils - A. Correct. CD18 is one member of the dimeric family of β 2 integrins. These are cell surface receptors that mediate cell adhesion and complement component binding. CD18 pairs with either CD11a, CD11b or CD11c to form LFA-1, CR3 or CR4, respectively. Thus, a mutation in CD18 will impair the function of three different cell surface receptors. The ligands for LFA-1 are ICAM-1, which facilitates leukocyte adhesion to endothelial cells. CR3 and CR4 bind iC3b, which promotes opsonophagocytosis of immune complexes that are coated with the complement component. This disease is called leukocyte adhesion defect-1 (LAD-1). The leukocytes of these patients do not bind iC3b well, but show normal complement activation, cytokine production and recognition of protein antigens. Thus, LAD patients suffer from two host defense problems: they do not extravasate leukocytes to sites of infection and they do not cannot use complement as an opsonophagocytic agent.
Quantitative test of immunoglobulins
This test measures the concentration of the five immunoglobulin isotypes in an unknown sample (e.g., serum).
The neutrophils (N) in the accompanying photomicrograph are arranged at the peripheral wall of the blood vessel shown. Which one of the following is CORRECT regarding their orientation in relation to the blood vessel?
Extravascular
Marginated
Mid-axial
Neutrophils should not be present in peripheral blood
Normal
Marginated - The neutrophils have marginated, due to the presence of selectins and chemotactic factors, which attract them to the site of injury. Normally, neutrophils assume a mid-axial location. Inflammation dilates the vessel and slows flow, allowing margination and exudation through the wall of the vessel into the extravascular space. A similar histologic appearance can be seen in an available Aperio virtual slide. Just focus on any artery, and you will be able to see margination and extravasation.
Which of the following processes are common to immature B cells and double positive thymocytes?
- Encounter with antigen can lead to lymphocyte maturation.
- Encounter with antigen induces BCR and TCR class-switching.
- Encounter with antigen leads to anergy.
- IL-2 expression promotes proliferation.
- TdT expression introduces random nucleotides into the μ and TCRβ genomic loci
Encounter with antigen can lead to lymphocyte maturation - When immature B cells and double positive thymocytes are stimulated by antigen, they can either undergo positive or negative selection. Positive selection results in lymphocyte maturation.
The image below depicts a portion of the Peyer’s Patches of the small intestine. Match the following functions with the letters that appear in the photomicrograph. Note that for clarity, some duplicate structures are labeled with the same letters. The site of proliferation and maturation of B lymphocytes is:
B - these are germinal centers
Which one of the following signaling intermediates is a kinase that phosphorylates the ITAMS of CD3 peptides when CD4 T cells are activated through their TCR?
Lck
Jak
Calcineurin
MyD88
PLCγ
Lck - Lck is a membrane-bound kinase associated with the CD4 coreceptor that augments TCR signaling in T cells.
ANA test does what?
E. The antinuclear antibody test measures circulating autoantibodies specific for any of a number of nuclear antigens.
A fluorescenated antibody to CD3 was used to stain sections of the spleen of normal mice. Which one of the following is a splenic structure that would be most intensely stained by this antibody?
Periarteriolar lymphoid sheath
Germinal center
Efferent lymphatic
Red pulp
White pulp follicles
Periarteriolar lymphoid sheath - T cells in the splenic white pulp are most concentrated within the PALS.
Superantigens bind?
MHC class II and the TCR
What chain is invariant in MHC class I?
Beta chain
In which one of the following protein domains are the polymorphic amino acid residues of HLA molecules primarily located?
Class I α1 domain
Class I α3 domain
Class II β2 domain
Class II β3 domain
β2-microglobulin domain
Class I α1 domain - Polymorphism of both Class I and Class II molecules is located primarily in the membrane-distal domains, such as α1.
You are characterizing the macrophage response to the bacterium Pseudomonas aeruoginosa. Knowing that this gram-negative bacterium has a potent endotoxin, you decide to determine if IL-1 transcription is activated in macrophages by the pathogen through a Toll-like receptor. Which of the following signaling intermediates is involved in this pathway?
c-Jun
NF-kB
PLCγ
Stat-1
ZAP-70
NF-kB
Factor I is responsible for inhibiting which of the following events:
C3b cleavage
C3a-mediated opsonization
C3d-mediated B cell co-activation
C4a-mediated opsonization
C5 cleavage
C5 cleavage
Complement fixation test measures?
complement consumption by antigen-antibody complexes and can be used to measure the amount of antigen or antibody in an unknown sample.
LFA-1 binds?
ICAM-1
Which one of the following cells of the innate immune system is capable of both high level phagocytosis and high level oxidant production?
Dendritic cells
Epithelial cells
Neutrophils
NK cells
NKT cells
Neutrophils
A clone of antigen-specific mouse B lymphocyes is activated with a protein antigen in vitro in the presence of T helper cells, and the expression of surface Ig molecules on the B cells is followed over time. Which one of the following events is most likely to occur in the B cells?
They will change from the expression of membrane IgG to membrane IgD.
They will change from the expression of membrane IgG to membrane IgM.
They will change from the expression of membrane IgA to membrane IgG.
They will change from the expression of membrane IgD and IgM to membrane IgG.
They will change from the expression of membrane IgM to membrane IgG and then back to membrane IgM.
They will change from the expression of membrane IgD and IgM to membrane IgG. - When B cells switch isotypes, they first switch from coexpression of IgM and IgD to some other isotype, most often IgG, depending on the signals they receive.
Which one of the following cell surface receptors is a member of the CD18 integrin family?
ICAM-1
IL-2R
Poly Ig receptor
TLR2
CR3
CR3 - Complement receptor 3 is a member of the b2 integrin family. It is comprised of a common β chain (CD18) paired with a unique α chain (CD11b).
Does the oral vaccine promote a carrier or non-carrier state?
Non-carrier
Which one of the following is a component of the innate immune system that can activate complement in a C2-dependent fashion?
α-defensin
Mannose-binding protein
IgG antibody
Fibrinogen
C-reactive protein
MBP (or mannose-binding lectin, MBL m) is a C1q-like protein that binds to microbial mannose residues and recruits MBL-associated serine protease (MASP). This protease has the same specificity as C1qr2s2 and cleaves C4 and C2 of the complement system. This is the lectin pathway of complement activation.
Superantigens are toxins produced by the bacteria Staphylococcus aureus and Streptococcus
pyogenes. Which of the following explains the ability of these superantigens to induce
excessive cytokine responses?
Activation by antigen of multiple IgGs, which then activate exponential numbers of
allergy-inducing cells, such as eosinophils and basophils
Activation of T cells by binding both the TCR and the MHC class II
Activation of Toll-like receptors on neutrophils
Crosslinking of the BCR by the Fc portion of IgG molecules
Crosslinking of the BCR by MHC class I
Activation of T cells by binding both the TCR and the MHC class II
Does the intramuscular vaccine promote a carrier or non-carrier state?
Carrier
Beta-2 microglobulin is a component of what pathway?
MHC class I pathway
In the accompanying low power photomicrograph of lung, the interlobar fissue labeled”F” conveniently divides the picture into halves. The alveoli (labeled “A”) on the left hand side of the picture are most likely filled with which one of the following?
Atmospheric dust and debris
Collagen
Edema fluid
Neutrophils and fibrin
Macrophages
Neutrophils and fibrin - The alveoli on the right are relatively empty, but on the left they exhibit acute pneumonia, and are filled with neutrophils and a variable amount of fibrin. This is the typical picture of acute inflammation, often due to pyogenic bacteria. The fibrin and neutrophils affect gas exchange, and the patient may become hypoxic. If the inflammation does not resolve quickly (because of antibiotics), the infiltrate may organize, and fibroblasts will lay down collagen and cause long-term scarring of the lung.
Which of the following functions is MOST commonly associated with IL-3?
Mast cell growth
CTL Production
Plasma cell differentiation
Th2 differentiation
Vascular permeability
Mast cell growth - IL-3 induces the growth of mast cells, granulocytes, erythroid cells, and megakaryocytes.
A patient with a gram-negative urinary tract infection suddenly becomes septic and you are considering potential soluble mediators of his acute systemic inflammatory response to infection. Which of the following soluble pattern recognition molecules is present in the serum of healthy individuals and would likely have contributed to the pathogenesis of sepsis in this patient?
Mannose-binding lectin
IgG antibody
Interleukin-2
Jak2 kinase
T cell antigen receptors
Mannose binding lectin - Complement has several components that are soluble pattern recognition molecules, including mannose-binding protein (recognizes bacterial mannose). MBP (MBL) is present in serum at high concentrations.
What is the letter A in this picture?
M cells
The healing soft tissue shown in the accompanying photomicrograph contains pink or hyalinized material interspersed between cell nuclei. Which one of the following words or phrases best describes the composition of this pink tissue?
- Collagen
- Edema
- Fibrin
- Necrotic tissue
- Protein
Collagen - The nuclei labeled “F” in the photomicrograph are fibroblast nuclei. Fibroblasts produce collagen, which is secreted, then assembled outside the cell. While collagen is certainly a protein, it is a more specific term, and is thus preferred. Collagen should always be associated with fibroblasts.
Which of the following proteins expressed by CD4+ T cells MOST contributes to macrophage activation?
CD28
CD154
CD132
IL-4
LFA-1
CD154 - Aka CD40 has two major functions activating macrophages and inducing class switching in B cells
Intramuscular vaccines produce what class of antibody?
IgG
The Haemophillus influenzae type B conjugate vaccine differs from the older Haemophillus polysaccharide vaccine in that the conjugate vaccine:
activates polysaccharide-specific T cell immunity.
stimulates formation of protective IgE antibodies.
induces memory B cells that produce IgG antibodies.
activates macrophages to produce IL-1b.
contains an adjuvant.
induces memory B cells that produce IgG antibodies. - Conjugate vaccines are composed of antigens covalently linked to protein immunogens. As such, they stimulate both B and T helper cells. With T cell help, isotype switching to IgG and memory B cell induction can occur. These vaccines are not designed to induce IgE antibodies.
Some patients with autoimmune diseases show poor clearance of soluble immune complexes from their blood circulation. This would suggest a defect in the functioning of which one of the following receptors?
CR1
CR2
CR3
CR4
FcgR
CR1 - Soluble immune complexes in circulation consist primarily of antigen complexed with either IgM or IgG antibodies. Being complement-activating, these complexes also have associated with them complement fragments derived from the classical pathway of activation. C3b or iC3b are the primary mediators of immune complex clearance from the circulation and bind to CR1 receptors found on erythrocytes.
What is C5b6789?
This is the membrane attack complex
What is the first step of the complement signaling cascade that is common to the classical, alternate, and lectin pathways?
C2 cleavage
C3 cleavage
C4 cleavage
C5 cleavage
Factor B cleavage
C3 cleavage
CD28 binds?
B7
Which of the following is an excellent “costimulator” of B lymphocytes that delivers a second signal to the cells?
Antimicrobial peptides
C3d
Interferon-gamma
Interleukin-15
Fc portion of IgG
C3d
A 14-year-old boy suffered from a splinter in his right finger, which became infected and inflamed. A large lymph node was found near his elbow, which his mother insisted must be removed. A representative section from the enlarged lymph node is shown at right in the accompanying photomicrograph, along with a normal lymph node that was removed at the same time. Which one of the following is the best diagnosis for the abnormal lymph node?
- Diffuse large B cell lymphoma
- Follicular hyperplasia
- Follicular lymphoma
- Hodgkin’s lymphoma
- Metastatic carcinoma
Follicular hyperplasia - The history suggests a benign, inflammatory process, which is confirmed by the histological appearance. The follicles f. encroach on the medulla, but do not move outside the capsule (as is often the case in follicular lymphoma).
Viral antigens can be presented by MHC class I expressed by infected epithelial cells. Which of the following proteins is MOST DIRECTLYresponsible for the destruction of the virus-infected epithelial cells by cells of the adaptive immune system?
C5b6789
IFNγ
IgA
IL-8
Granzyme B
Granzyme B - CD8+ T cells destroy infected cells using either Granzyme B or Fas.
Which of the following best describes the function of the CD4 molecule?
Binds B7 molecules
Binds ICAM-1
Binds non-polymorphine residues of MHC class II
Binds superantigens
Binds VCAM-1
Binds non-polymorphine residues of MHC class II
If the broad bands of collagen seen in the lower half of this photomicrograph were analyzed biochemically, they would be found to contain which one of the following collagen types?
Type 3 - This is a keloid, and type 3 collagen is never remodeled to type 1.
Which one of the following proteins or group of proteins can act as an opsonin?
C3b
IL-8
ß-defensins
lysozyme
secretory component
C3b is an effective opsonin and binds antigen-antibody complexes or C3b-coated microbes to phagocytic cells through their complement receptors (CR3 and CR4).
Which one of the following is a property of NKT cells, but not conventional αß T cells?
The expression of Rag-1 and Rag-2
Specificity for glycolipid antigens
The expression of the co-receptor CD28
Lysis of target cells through a Fas-dependent mechanism
Production of IFN-γ
Specificity for glycolipid antigens - While conventional T cells recognize peptide antigens presented by the host MHC molecules, NKT cells recognize glycolipids presented by CD1 molecules on antigen-presenting cells.
Which one of the following lymphocyte subsets bears an antigen receptor that recognizes glycolipid, rather than protein, antigens?
NKT cell
CD8 TCRαβ T cell
CD4 CD8 thymocyte
Double negative thymocyte
Pre-TCR thymocyte
While the TCR of NKT cells is comprised of αβ heterodimers similar to those of the conventional TCRs, they recognize glycolipid antigens presented by CD1 molecules.
IL-2 does what?
It mediates the activation of cell proliferation in T and B lymphocytes, two component of the adaptive immune system.
From analysis of the accompanying high power photograph, how would you classify the acute inflammatory exudates seen?
Eosinophilic
Fibrinous
Fibrous
Granulomatous
Purulent
Fibrinous - The photomicrograph shows an abundance of fibrin strands f.. By definition, this is a fibrinous exudate. An acute inflammatory exudate on a serosal surface usually contains plentiful fibrin, e.g., as in so-called “bread and butter” pericarditis
Which of the following cells is MOST likely to present antigen to CD4+ Th1 cells?
B cells
Dendritic cells
Macrophages
Monocytes
Neutrophils
Th1 cells are effector cells that migrate to the site of infection. At the site of infection, the most likely APCs found are macrophages. DCs migrate to the lymphoid tissues. B cell-T cell interactions are most likely found in lymphoid tissues. Monocytes are in blood. Neutrophils do not express MHC class II.
CR2 has what role?
coreceptor found on B cells that coactivates B cells when they bind both antigen (the ligand for the BCR) and the complement peptide C3d (the ligand for CR2).
Which one of the following is true regarding the T cell antigen receptor?
Its V region genes undergo a high rate of mutation following cell activation by antigen.
The cytoplasmic domains of the α and β chains contain several ITAM motifs.
It shows a high affinity (Ka < 100 nM) for peptide-MHC complexes.
It signals gene transcription primarily through the JAK/STAT pathway.
The receptor is never expressed in the absence of CD3 peptides.
The receptor is never expressed in the absence of CD3 peptides. - TCR are never expressed in the absence of their CD3 peptide partners. This is emphasized by examining CD3-null strains of mutant mice.
A patient appears to have an antibody deficiency due to an absence of B cells, and you decide to treat her with IVIG. Fifteen minutes after injecting the drug, you measure her serum IgG level and it is found to be 30 mg/dL. What concentration of IgG would you expect to find in this patient’s serum 6 weeks after drug delivery?
Undetectable
3 mg/dL
7 mg/dL
15 mg/dL
30 mg/dL
7 mg/dL - the half life of IgG is approx 3 weeks
Administering only the oral polio vaccine has which of the following advantages over administering only the intramuscular polio vaccine?
- Induces IgA production
- Induces IgG production
- Induces a T-dependent antibody response
- Permits a carrier state
- Prevents CNS infection
An oral vaccine promotes immunity in which IgA antibody is the dominant type
A pediatric patient presents with recurrent infections and you hypothesize that she has a defect in killing phagocytized bacteria. Which one of the assays listed below would best allow you to test this hypothesis?
Complement fixation test
Quantitative test of immunoglobulins
Mixed lymphocyte reaction
NBT dye reduction test
ANA test
NBT dye reduction test - Nitroblue tetrazolium test meadures the production of oxidants that are important mediators of oxidative damage to phagocytized microbes.
