Immunology Past Exam Questions

The primary lymphoid organs where B and T cells mature are ____ and _____

bone marrow; thymus

The secondary lymphoid tissues where the adaptive immune response is generated are:

spleen; lymph node

The three transcription factors that are induced upon TCR signaling are ____, ____ and ____

NFAT, AP-1, NFkb

All three transcription factors lead to the production of the cytokine ____ which is necessary for the proliferation of recently activated T cells

IL-2

B cell first row

IgA, IgB

T cell second row

CD4, CD8

T cell third row

CD28

T cell 4th row

Lck

T cell last row

Itk

B cell 5th row

Syk

B cell 6th row

SLP-65

One way by which cytotoxic T cells kill infected cells is release of cytotoxins stored in granules such as ____, _____ and granulysin.

perforin, granzymes

One death ligand expressed by cytotoxic T cells is ____

FasL

Cytotoxic T cells also secrete cytokines such as ___

IFNy

During the first stage of B cell development, the ___ stage

pro-B cell

Rag-1 and Rag-2 expression is induced to permit D-J rearrangement and then ___ rearrangement on the ____ locus

VDJ, heavy chain

Once ___ gene is productively rearranged, u chain will be expressed.

heavy chain again

together with VpreB and lambda5, they form the ___ on the cell surface

pre B cell receptor

This drives the transition into the ____ stage

pre B cell

when ____ locus undergoes ____ rearrangement.

light chain, VJ

Productive rearrangement produced surface immunoglobulin ____ and the cells become immature B cells

IgM

Mature B cells express high levels of immunoglobulin ___

IgD

Naive B and T cells are recruited to lymph nodes for they express the chemokine receptor ____

CCR7

Once in the lymph node, B cells further migrate to the B cell zones due to their expression of another chemokine receptor ___

CXCR5

some B cells form the primary focus where they first differentiate into antibody synthesizing ____ that are still dividing

plasmablasts

Eventually, the antibody secreting, long lived ____ emerge

plasma cells

In the dark zone, B cells are called ____ and they are highly proliferative

centroblasts

B cells express an additional chemokine receptor ____ to enter the dark zone

CXCR4

B cells that slow down proliferation and return to the light zone are called _____

centrocytes

In the light zone, B cells with high affinity B cell receptors are more effective in capturing antigens trapped on the surface of ___ cells

follicular dendritic cells

The antigens are endocytosed processed and presented to ____ cells for their help.

follicular helper T cells

For example, the dimeric form of ___ is found in secretions such as breast milk

IgA

while ____ is mostly associated with mast cells underneath the epithelium

IgE

In patients with lymphomas, the cancer cells invade the bone marrow and destroy the environment required for normal hematopoiesis. This leads to bone marrow failure which disrupts the production of hematopoietic cell lineages. All of the following cell types would be affected by this except:

Macrophages

T cells

NK cells

Skin cells

Neutrophils

Skin cells

Neutrophil defensins are___

anti-toxins

reactive oxygen species

proteases

glycolipids

short peptides

short peptides

Which of the following statements is TRUe of lysozyme?

Lysozyme is released by mast cells

Lysozyme is a cytoplasmic organelle

Lysozyme activates complement

Lysozyme is a proteolytic enzyme

Lysozyme splits peptidoglycan

Lysozyme splits peptidoglycan

Which of the following classes of cell surface receptors is NOT directly encoded in the germline?

CD4 or CD8

Toll-like receptors

NK receptors

T cell receptors

None

T cell receptors

When tissue resident macrophages encounter bacteria, they release cytokines that induce an inflammatory response. These cytokines act on other immune cells, to recruit them to the site of infection and to enhance their activities. In addition, these cytokines act on the endothelial cells of the blood vessel wall to:

secret anti microbial peptides

proliferate allowing the blood vessel to enlarge

Increase their permeability allowing fluid and proteins to leak into the tissue

solidify the tight junctions to prevent the bacteria from entering the blood

up regulate microbial mechanisms so they can directly kill bacteria

Increase their permeability allowing fluid and proteins to leak into the tissue

Structurally and functionally mannose-binding lectin is most similar to:

Bb

C1q

C1r

C4b

C5a

C1q

Even when the complement cascade fails to proceed beyond generating the C3 convertase, complement activation is effective at inducing pathogen uptake and destruction. This process of immune protection is mediated by:

-activation of complement inhibitory receptors on phagocytes that promote pathogen uptake

-activation of soluble proteases in the serum that disrupt pathogen membranes

-engagement of complement receptors by C3b which promotes phagocytosis

-engagement of complement receptors on B cells that promotes antibody production

-stimulation of antimicrobial peptide secretion by phagocytes

engagement of complement receptors by C3b which promotes phagocytosis

True or False: Macrophages, Neutrophils, and DCs are all phagocytes. Because of this, they can present pathogen derived protein antigens to T cells. In this regard, they are antigen presenting cells as well.

False

A typical immunoglobulin G (IgG) contains ____ antigen binding sites and a total number of ___ CDRs from both the heavy and the light chains.

1:3

2:6

1:6

2:12

4:12

2;12

True or false: The antibody protein has two functional domains one for antigen binding and a second to confer specific effector functions. The former is encoded by the light chain and the latter by the heavy chain.

False

True or false: T cell receptor structure is much simpler than that of a B cell receptor. TCR mimics the Fab region in a BCR. Therefore, TCR is completely made up of variable regions unlike BCRs which have both variable and constant regions.

False

CD4 positive T cells recognize their antigen presented by which molecules?

BCR

IgM

MHC Class 1

MHC Class 2

TCRb

MHC class 2

The antibody surface involved in antigen binding varies depending on the size and nature of the antigen. This surface can be concave or flat and sometimes can have extended protrusions. This is accomplished by:

-flexibility in the hinge regions of the antibody allowing rotation of the antigen binding sites

-some antibodies using V region framework sequences instead of the CDRs to bind antigen

-The ability of different CDR sequences to form many structurally distinct shapes and surfaces

-the ability of the same heavy chain to pair with different light chains

-the differential usage of k versus lambda light chains, as k chains form concave binding sites whereas lambda chains make flatter surfaces

The ability of different CDR sequences to form many structurally distinct shapes and surfaces

True or False: each family of NK cell receptors has membranes that promote NK cell activation, and members that send inhibitory receptors lies in their association with accessory proteins that promote downstream signaling or in their ability to recruit and activate inhibitory phosphatases respectively.

True

A chromosome on which T cell receptor B chain gene rearrangement has occurred lacks which of the following gene segments?

Joining J

Diversity D

Variable V

Constant C

All are present

All are present

The processing of cytosolic proteins for MHC presentation involves:

Transport into late endosomes

proteasome mediated degradation

displacement of invariant chain

displacement of B2 microglobulin

binding to the MHC class 2 groove

proteasome mediated degradation

Non classical MHC molecules are often found on the surface of stressed cells. Instead of T cell receptors they may engage NK receptors. what is the receptor for Type-1 non classical MHC molecules MIC-A/B?

Toll like receptor 5

CD4

CD8

NKG2D

Fas death receptor

NKG2D

endothelial cell activation

Local secretion of pro-inflammatory cytokines

rolling

interaction of P/E selectin with sulfated sialyl lewis X

strong adhesion

Neutrophil LFA-1 with endothelial ICAM-1

Diapedesis

neutrophil squeeze between endothelial cells

artemis

nuclease activity to open the DNA hairpin and generate P nucelotides

Rag1/2

Recognize RSS and create single stranded break

DNA Ligase IV

Join DNA ends to reform continuous chromosomes

TdT

Non template addition of N nucleotides at segment junction

Many different viruses encode proteins that function to down regulate MHC class 1 expression on host cells following infection with the virus. This immune evasion mechanism allows the virus to hide from CD8 T lymphocytes that normally detect virus infected cells by using their T cell antigen receptor to recognize viral peptides bound to MHC class 1 proteins on the surface of the infected cell. To counteract this immune evasion strategy, NK cells have:

-Activating receptors that recognize MHC class 1 proteins

-a mechanism to secrete antiviral peptides

-inhibitory receptors that recognize viral capsid proteins

-activating receptors that recognize viral capsid proteins

-inhibitory receptors that recognize MHC class 1 proteins

-inhibitory receptors that recognize MHC class 1 proteins

Phosphatidylinositol biphosphate PIP2 is a common phospholipid found on the plasma membrane. Cleavage of PIp2 generates two second messengers, DAG and IP3. This reaction is catalyzed by the enzyme___

calmodulin

protein kinase A

protein kinase C

PLC-y

ZAP-70

PLCy

after T cell activation, many cytosolic proteins are recruited to the TCR complex because they can bind to the phosphorylated tyrosine residues. The ____ domain in these proteins are responsible for binding to phosphorylated tyrosines.

ITAM

NZF

PH

SH2

SH3

SH2

Which of the following alterations would result in increased activity of Ras?

a mutation in Ras that enhances GTPase activity

a mutation in Ras that redners it incapable of binding to any form of guanine nucleotides

depletion of GTP in the cytoplasm

overexpression of GAPS

over expression of GEFs

over expression of GEFs

True or False: CTLA-4 and PD-1 are both inhibitors of T cell activation. They both bind to B7 molecules to outcompete CD28

False

Which of the following options correctly describes a difference between the B cell receptor and T cell receptor?

-T cells do not require the formation of a pre T cell receptor to advance their development, as opposed to B cells which require signaling through the preB cell receptor in order to undergo allelic exclusion and continue development

-expression of the B cell receptor stops further light chain rearrangement and enforces strict allelic exclusion while expression of the T cell receptor does not restrict further rearrangements of the alpha chain until there is signaling through peptide MHC binding, recruiting in many T cells that express two different TCRa chains.

expression of the B cell receptor stops further light chain rearrangement and enforces strict allelic exclusion while expression of the T cell receptor does not restrict further rearrangements of the alpha chain until there is signaling through peptide MHC binding, recruiting in many T cells that express two different TCRa chains.

True or False: In negative selection, B cells that interact strongly with self antigens may be rescued by receptor editing. during receptor editing both heavy and light chain loci go through successive rearrangement events until the B cell produces a new B cell receptor that is not self reactive.

False

Self reactive B cells can be eliminated from the repertoire at several stages of B cell maturation including immature B cells that have already emigrated from the bone marrow into the circulation. this latter stage of tolerance induction is critical because:

-immature B cells are trapped in the bone marrow

-circulating immature B cells do not encounter tissue specific antigens

-receptor editing is not a perfect process

-not all self antigens are expressed or present in bone marrow during B cell development

-immature circulating B cells are more sensitive to antigen stimulation than developing B cells

-not all self antigens are expressed or present in bone marrow during B cell development

In mice that lack MHC class 2 in the thymus, T cell development will show:

-a block in T cell development at the CD4+CD8+ double positive stage

-a block in the T cell development at the CD4-CD8- double negative stage

-normal number of mature CD4+ T cell no mature CD8+ T cells

-Normal number of mature CD8+ T cell, no mature CD4+ T cells

-normal numbers and subsets of thymocytes and peripheral T cells

-Normal number of mature CD8+ T cell, no mature CD4+ T cells

Which of the following descriptions is not correct about T regulatory cells?

-treg cells are a subset of CD4+ T cells

-in the thymus, Treg cells pass positive selection because their TCRs interact with self peptide: self MHC complex with extremely low affinity

-treg cells express high affinity Il-2 receptor but do not produce IL-2

-treg cells express FoxP3 transcription factor

-in many cases, autoimmunity is the product of hypoactive treg cells

-in the thymus, Treg cells pass positive selection because their TCRs interact with self peptide: self MHC complex with extremely low affinity

strep throat is commonly caused by group A steptococcus bacteria. a common symptom of strep throat is the presence of swollen lymph nodes in the neck. this symptom usually peaks about 2-4 days after the onset of the infection and is due to:

-damage to the pharyngeal epithelium by the bacteria

-trapping and activation of antigen specific lymphocytes in the lymph nodes of the neck

-release of bacterial PAMPs leading to inflammatory cytokine production

-recruitment of neutrophils to the lymph nodes of the neck

-recruitment of circulating macrophages to the lymph nodes of the neck

-trapping and activation of antigen specific lymphocytes in the lymph nodes of the neck

True or False: Naive T cells scan the dendritic cells in the cortical region of the lymph nodes as they migrate. the initial encounter of T cells with dendritic cells is mediated by interactions between the T cell receptor and the peptide MHC complexes on the dendritic cell

False

When Langerhans cells migrate to local lymph nodes and differentiate into fully mature dendritic cells they:

down regulate MHC2 expression

increase their endocytic activity

increase expression of B7.1

decrease expression of B7.2

become resistant to infection by HIV-1

increase expression of B7.1

Which of the statements below is TRUE about somatic hypermutation?

is common for both BCRs and TCRs

takes place in bone marrow

only applies to the light chain

requires reactivation of RAag1/2 and TdT

may decrease the affinity of a BCR

may decrease the affinity of a BCR

True or false: all cell surface Fc receptors bind antibodies with low affinities. In the absence of antigens, antibodies do not associate with cell surface Fc receptors

False

CCL19/21

Promote naïve T cell entry into lymph nodes

Sphinogosine 1-phosphate (S1P)

promote naive T cell migration out of the thymus

CXCL13

attract B cells to B cell zones in lymph nodes

B7 molecules

CD28

peptide:MHC complex

TCR

ICAM-1

LFA-1

The final stages of T cell development occur in the thymic medulla, after the developing cells become CD4 or CD8 single positive. One important change that occurs during this final maturation is:

-the downregulation of the pre T cell receptor

-the upregulation of genes encoding effector cytokines

-the increased susceptability to T cell receptor induced apoptosis

-the loss of susceptibility to T cell receptor induced apoptosis

-the upregulation of signaling proteins required for T cell activation

-the loss of susceptibility to T cell receptor induced apoptosis

Wiskott-Aldrich syndrome is an immunodeficiency disease that causes a defect in antibody responses. The most severe defects are in antibody responses to protein antigens which are dependent on CD4 effector TFH cells providing cytokines to the B cell. This immune defect could be fixed by a gene therapy approach that restored WASp expression in:

APCs such as DCs

B cells

Stromal cells

T cells

T and B cells

T cells

M cells

phagocytosis

Paneth cells

secretion of antimicrobial peptides

Goblet cells

mucus secretion