Immunology Exam 5 +fe

Primary lymphoid organs are sites where lymphocytes can mature prior to populating the secondary or "peripheral" lymphoid organs. Which one of the following is NOT true?

Response to, and elimination of foreign immunogens occurs mostly in the primary lymphoid organs

Which of the following would make the best immunogen?

A 100,000 Da protein made up of multiple amino acid type

Which of the following is NOT a likely epitope to which a B-cell could respond?

hydrophobic

why? bc B cell responds to external, hydrophilic, sequential, and non-sequential.

Which of following events contributes to antibody diversity in a developing B-cell in the bone marrow?

Recombination of multiple germ line gene segments.

The ability of a single mature B lymphocyte to express both surface IgM and IgD is made possible by which one of the following?

differential RBA processing

Which one of the following does NOT apply to IgA which is secreted at mucosal surfaces?

Secretory IgA associates with high affinity Fc receptors on the surface of mast cells and basophils.

Certain proteases have the ability to cleave IgG molecules into fragments. Which statement is NOT true with respect to these immunoglobulin fragments?

The Fc fragment contains an antigen binding site encoded by variable region gene sequences

Each immunoglobulin class designation is based upon which of the following?

the type of heavy chain expressed

Which of the following statements is false?

Each B cell procedure an antibody

The molecules important in initiating intracellular events after antigen binding to membrane immunoglobulin on a naive B cell are:

Ig alpha and ig beta

One step in the differentiation of B lymphocytes that requires exposure to antigen is

formation of memory B cells.

With regard to the rearrangement of immunoglobulin genes, which of the following are true?

• Although each B cell carries two alleles encoding the immunoglobulin heavy and light chains, only one allele is expressed

• Once a B cell heavy chain rearranges its VDJ segments, this gene encodes the heavy chain variable region that this B cell will express for the rest of its life

The ability of some members of a population to survive a disease epidemic is primarily due to:

The highly polymorphic nature of the MHC

T-lymphocytes express which antigen presenting molecules on their cell surface?

MHC class I molecules only

T-lymphocytes express which antigen presenting molecules on their cell surface?

MHC Class I molecules only

Dendritic cells express which antigen presenting molecules on their cell surface?

MHC class I and MHC class II molecules and CD1

Given a common binding affinity, rank the following secreted antibody isotypes in order of avidity:

IgM > IgA > IgG

or igG < IgA< IgM

Which of the following is not an interaction responsible for antibody-antigen binding?

Covalent bonds

Processing of an exogenous protein antigen by a macrophage involves which one of the following:

replacement of the CLIP within the MHC binding groove by the antigenic peptide

Antigen receptors on T lymphocytes and antigen receptors on B lymphocytes have all of the following in common EXCEPT for which of the following?

Each recognize antigens combined with MHC molecules

There are similarities and differences between the mechanisms used by B and T lymphocytes to generate antigen receptor diversity. Which mechanism(s) is/are not used by T lymphocytes?

somatic hypermutation

Proliferation and differentiation of lymphocytes in response to foreign antigens usually takes place in the

lymph nodes

Which of the following are NOT found in the thymus?

cells expressing both gamma/delta T cell receptors and alpha/beta T cell receptors at the same time

Assuming both cell types are initially naive, place these events in T-cell dependent B-cell activation in

the correct sequence:

1. Phosphorylation of ITAMs on CD3

2. Activation of Syk

3. Interaction of CD40 ligand with CD40

4. Activation of Zap70

5. Endocytic pathway of antigen processing

2, 5, 1, 4, 3

• activation of syk

• endocytic pathway antigen processing

• Phosphorylation of ITAMs on CD3

• Activation of Zap70

• Interaction of CD40 ligand with CD40

T lymphocyte antigen receptors recognize peptides:

. that are presented to them by antigen presenting cells

With regard to the process of negative selection within the thymus, which one of the following is TRUE?

Thymocytes that recognize self antigens too well are killed

With regard to the process of positive selection within the thymus, which one to the following is TRUE?

Thymocytes that can interact with self MHC molecules are permitted to survive.

Which of the following is TRUE following the interaction of the T cell receptor with antigen

• an intracellular signal is transduced through proteins of the CD3 complex.

• phosphatidylinositol 4,5 biphosphate hydrolysis to diacylglycerol and inositol 1,4,5-triphosphate occurs.

• a rise in intracellular calcium and protein phosphorylation occurs.

• translocation of transcription factors to the nucleus occurs.

all of the above

The CD4 molecule

stabilizes T cell receptor/ class II MHC interaction

The majority of T lymphocytes have an antigen receptor, which is composed of

Alpha and beta chains

All of the following correctly describe gamma-delta T-cells EXCEPT:

gamma-delta T cells express both CD4 and CD8

. Place these events during B-cell development in the correct order:

1. Genes encoding the light chain are rearranged

2. Membrane bound IgM is expressed

3. TdT is inactivated

4. D to J gene segment joining

5. Membrane bound IgD is expressed

4, 3, 1, 2, 5

D to J gene segment joing

TdT is inactivated

Genes encoding the light chain are rearranged

Membrane bound IgM is expressed

Membrane bound IgD is expresse

All of the following correctly describe natural killer (NK) cells except

NK cells have antigen specific receptors

Cytotoxic T lymphocytes recognize peptide antigens which are presented to them on:

MHC molecules composed of an alpha chain associated with beta 2 microglobulin

Killing of cells by cytotoxic T lymphocytes (CTL)

requires contact between the CTL and the target for killing to occur

A major function of CD8 positive lymphocytes is:

it kills cells expressing foreign peptides presented by MHC molecules

A major function of CD4 positive lymphocytes is:

to produce cytokines which help immune responses

Regarding antibody dependent cell-mediated cytotoxicity (ADCC), which of the following statement(s) is/are TRUE:

A. ADCC can be mediated by natural killer cells or macrophages.

B. ADCC requires antibody recognition of an antigen on the surface of a cell.

C. ADCC requires expression of an Fc receptor by the effector cell

ALL of the ABOVE

Cellular cytoxicity mediated by natural killer (NK) cells have which of the following characteristics?

• NK cells can secrete granules containing pore-forming proteins

• NK cells can secrete toxic cellular enzymes, like granzyme

The C3b complement component is important for which complement effector function?

opsonization

The C5a complement component is important for which complement effector function?

• as a chemoattractant molecule

• mast cell activation

Place the following molecules in order of their formation during the classical pathway of complement activation.

3, 1, 5, 4, 2

C4a

C4b2a

C3b

C5a

MAC

Which of the following events does NOT occur during the alternative pathway of complement activation?

C1 activates both C4 and C2

Which of the following can activate complement via the classical pathway when complexed with antigen?

one IgM molecule

Which of the following is a Th1 type cytokine?

IL-2

IL-2 is a cytokine that is produced by T cells and promotes the growth and differentiation of naive T cells into effector Th1 cells.

Which of the following statements is/are TRUE about TH1 and TH2 type cytokine production?

• Positive feedback loop exists

• Negative cross regulation occur

Which of the following is a mechanism that explains the cytokine attribute of pleiotropy?

Different signal transduction pathways and/or gene promoters are activated

Which of the following is NOT a rapid event during inflammation

T-cells clonally expand

Naive T-cells can extravasate:

Only across specialized endothelial linings

Place the following events during neutrophil extravasation in the correct order:

1. neutrophil arrest and adhesion

2. elevated expression of cell adhesion molecules on enthothelial cells

3. neutrophil transendothelial migration

4. weak binding of neutrophil to endothelial cells

5. elevated expression of cell adhesion molecules on neutrophils

2, 4, 5, 1, 3

• elevated expression of cell adhesion molecules on enthothelial cells

• weak binding of neutrophil to endothelial cell

• elevated expression of cell adhesion molecules on neutrophils

• neutrophil arrest and adhesion

• neutrophil transendothelial migration

Delayed type hypersensitivity reactions are characterized by which one of the following.

the activated macrophage as the principal effector cell.

The symptoms of mismatched blood transfusion reactions may be ascribed to which type of immune hyper-responsiveness?

Type II hypersensitivity

Which of the following is NOT an example of a type I hypersensitivity?

Hyperacute graft rejection

• mediated by antibodies not IgE

The symptoms of acute graft rejection may be ascribed to which type of immune hyper- responsiveness?

Type IV hypersensitivity

The principal effector immune cells involved in type IV hypersensitivity responses are:

Macrophages and T cells.

These cells are responsible for the delayed reaction and tissue damage associated with this type of hypersensitivity.

Place the following events during the development of a type I hypersensitivity response in the correct

sequence

1. vasodilation and bronchconstriction

2. isotype switching

3. degranulation of mast cells

4. binding of IgE to Fc receptors

5. activation of allergen specific B-cells

5, 2, 4, 3, 1

• 5. activation of allergen specific B-cells

• 2. isotype switching

• 4. binding of IgE to Fc receptors

• 3. degranulation of mast cells

• 1. vasodilation and bronchconstriction

The principal secreted immunoglobulin isotype involved in the development of type I hypersensitivity is

IgE

One of the first mediators released by basophils or mast cells during an allergic reaction is:

Histamine

A person with type AB blood may accept blood donated from a donor with which of the following blood types?

A, B, O, and AB

Considered universal recipient

Which of the following statements is NOT true for type III hypersensitivity responses?

They result in the formation of a granuloma

Which of the following is NOT attributed to type IV hypersensitivity responses?

Allergic Eczema

Eczema is mediated by T cells and does not involve antibodies.

What is attributed to IV? Granuloma formation, poison ivy rxn, tissue destruction, fibrosis (scare tissue)

IgE may play a protective role against which kind of infection?

Parasitic infections

Which of the following is our best protection against infectious organisms?

Our skin

It acts as a physical barrier and is part of the innate immune system, preventing pathogens from entering the body.

Which of the following provides innate defense against viral infections?

Natural killer cell

Large changes in the composition of viral protein coats can lead to wide spread outbreaks of old diseases. These large changes are known as

Antigenic shift

Which of the following evasion mechanisms would be expected to benefit a virus?

Inhibition of TAP molecules

Which of the following evasion mechanisms would be expected to benefit a virus?

Inhabitation of TAP molecules

Which of the following does NOT play a key role in our defense against extracellular bacteria?

Tumor necrosis factor beta

Optimal immune responses to extracellular bacteria occur when which of the following occurs?

Activation of complement

Which of the following plays a key role in an effective defense against intracellular bacteria?
Which of the following plays a key role in an effective defense against intracellular bacteria?

Delayed type hypersensitivity responses

Which of the following statements is FALSE?

Parasitic worm infections provoke strong immune responses due to their large numbers within the body

Which of the following vaccine strategies would be best for long term protection against an intracellular bacteria?

Attenuated whole organism vaccine

A disadvantage of using polysaccharide vaccines is:

it does not result in the activation of T-helper cells and may not produce lasting immunity.

Vaccine are useful because

• they are cost effective weapons for disease control

• . they promote immunity to infectious micro-organisms

• they DO NOT always activate

Which of the following is TRUE for passive immunization?

It provides transient protection against disease

Artificial passive immunization is appropriate for all of the following EXCEPT:

Travellers who will spend an extended period of time in an area where a disease is endemic

Which of the following types of vaccines have a risk of reverting to a virulent (disease causing) form?

Attenuated virus or bacteria vaccines

The development of an AIDS vaccine has been very difficult due to:

A high level of antigenic shift shown by HIV

In which of the following diseases are blocking antibodies formed against the acetylcholine receptors on motor end-plates resulting in muscle weakness and atrophy?

Myasthenia gravis

Which of the following is an example of an organ specific autoimmune disease in which cytotoxic T- lymphocytes cause direct damage to self tissue?

Insulin dependent diabetes mellitus

Which of the following statements regarding autoimmunity is FALSE?

All self-reactive lymphocytes are deleted during maturation

Multiple sclerosis is associated with which of the following

cell-mediated immune responses against the myelin coat of nerve cells

Which of the following is NOT considered to be a possible mechanism for the development of autoimmunity?

Mismatched HLA antigens

The autoimmunity against heart valve cells (rheumatic fever) after a streptococcal infection is thought to occur as a result of which of the following mechanisms?

molecular mimicry

Which of the following is NOT true for autoimmune responses?

Interferon-gamma producing cells block or reduce autoimmunity

Which of the following is NOT an effective treatment for autoimmune diseases?

Vaccination

Transplantation of tissue from one individual to another unrelated individual of the same species is an example of which type of transplant?

allograft

. Which of the following characteristics are exhibited by acute tissue rejection?

Specificity and Memory

Which of the following statements regarding skin transplant rejection is not correct?

Tissue rejection does not display memory of previous grafts

Which of the following is TRUE for acute transplantation rejection?

It is caused by the cell-mediated arm of the immune system

The principle transplanted tissue antigens recognized by the immune system are:

MHC molecule

The principle transplanted tissue antigens recognized by the immune system are:

Alloantigens

The effector stage of acute transplant rejection involves which of the following?

• The production of IL-2 by T-helper cells

• The formation of sensitized delayed type hypersensitivity T-cells

• The formation of activated cytotoxic T-lymphocytes

• The occasional involvement of antibodies and ADCC

all of the above

Which of the following is NOT a method to reduce transplant rejection?

Drugs that inhibit meiosis

If the donor and the recipient were NOT matched correctly, which of the following transplanted tissues would be LEAST likely to cause a rejection response

Cornea

lacks MHC

Which of the following is NOT recognized as playing a role in the conversion of normal cells to

cancerous cells?

Adjuvants