Ch.15- Study Bank Questions

Generally antigenic molecules usually have a molecular weight greater than

10,000 Daltons.

How long after initiation of a primary response do significant amounts of antibody appear in the blood?

10-14 days

The immunoglobulin monomer consists of

2 heavy and 2 light chains.

There are ______ classes of antibody.

5

In opsonization with IgG, why would it be important that IgG react with the antigen BEFORE a phagocytic cell recognizes the antibody molecule? A. If the IgG bound to the phagocyte BEFORE opsonization, it would most likely be ingested by the phagocyte before it could bind to a pathogen (it would be 'naked,' so to speak). B. Binding of IgG by phagocytes would block the antigen binding sites on the IgG molecules, preventing them from binding to the microbes. C. Binding of IgG by phagocytes changes their conformation-and by changing their protein conformation, their antigen binding sites are changed and they can no longer recognize their specific antigenic epitopes. D. Binding of antibody by phagocytes results in immediate release of protein-destroying enzymes to the outside of the cell. Since antibodies are proteins, they would be destroyed by these enzymes (and would then be unable to bind to their specific antigenic epitopes).

A. If the IgG bound to the phagocyte BEFORE opsonization, it would most likely be ingested by the phagocyte before it could bind to a pathogen (it would be 'naked,' so to speak).

The function of the secretory component of the IgA molecule is to protect____ from being destroyed by proteolytic enzymes. A. IgA B. IgD C. IgG D. IgE

A. IgA

Which of the following antibodies is a dimer? A. IgA B. IgD C. IgM D. IgE

A. IgA

Which of the following class of antibody is primarily found in external secretions? A. IgA B. IgD C. IgG D. IgE

A. IgA

Which of the following is the most abundant immunological class produced? A. IgA B. IgD C. IgG D. IgE

A. IgA

How is a T-cell receptor different from a B-cell receptor? A. T-cell receptors must have antigen broken down inside a cell and presented to them by a Major Histocompatibility Complex (MHC) molecule. B. B-cell receptors must have antigen broken down inside a cell and presented to them by a Major Histocompatibility Complex (MHC) molecule. C. T-cell receptors are composed of 4 protein chains (pieces), while B-cell receptors are composed of only 2 pieces. D. T-cell receptors are eventually secreted into the bloodstream by activated T-cells, whereas B-cell receptors are not; they always stay with the B-cell.

A. T-cell receptors must have antigen broken down inside a cell and presented to them by a Major Histocompatibility Complex (MHC) molecule.

T-independent antigens A. include polysaccharides. B. require the involvement of T cells. C. interact with MHCI molecules. D. are usually proteins. E. include polysaccharides AND are usually proteins.

A. include polysaccharides.

Which of the following is not typical of an antigen? A. low molecular weight B. protein C. foreign D. polysaccharide E. low molecular weight AND protein

A. low molecular weight

_____ interact with antibodies at the outer end of each arm of the Y.

Antigens

________ is a form of cell suicide AND is induced in target cells by effector T cytotoxic cells.

Apoptosis

Antibodies are made by

B cells/plasma cells.

How is the central portion of a T-cell receptor complex functionally analogous to the center of the B-cell receptor complex? A. It has 2 pieces (chains), just like a B-cell receptor. B. Both receptors bind epitopes (small amino acid sections of antigen molecules). C. Both bind structures directly on the surface of microbes. D. Both can be secreted from lymphocytes to bind to pathogens under certain situations.

B. Both receptors bind epitopes (small amino acid sections of antigen molecules).

Which is the first antibody class made during the primary response to an antigen? A. IgA B. IgM C. IgG D. IgE

B. IgM

T cells primarily are responsible for A. humoral immunity. B. cell-mediated immunity. C. anamnestic immunity. D. producing haptens.

B. cell-mediated immunity.

Why would a person who has AIDS be more susceptible to the bacterium that causes tuberculosis? A. HIV (which causes AIDS) directly infects and destroys CD8+ T-cells. These are the cells that would actively destroy the bacterium that causes tuberculosis. B. HIV (which causes AIDS) directly inhibits the production of interferons. Interferons have a strong natural antibacterial activity, and are necessary for elimination of the bacterium that causes tuberculosis. C. HIV (which causes AIDS) destroys CD4+ helper T-cells. These are the cells that help activate and increase the bacteria-destroying capabilities of macrophages. Activated macrophages are required to help clear out the bacterium that causes tuberculosis, so without the CD4+ T-cells, we won't have activated macrophages. D. HIV (which causes AIDS) directly infects and destroys antibody-producing B-cells. Without the ability to produce antibodies, we can't opsonize and ingest/destroy the bacterium that causes tuberculosis.

C. HIV (which causes AIDS) destroys CD4+ helper T-cells. These are the cells that help activate and increase the bacteria-destroying capabilities of macrophages. Activated macrophages are required to help clear out the bacterium that causes tuberculosis, so without the CD4+ T-cells, we won't have activated macrophages.

Which class of antibody accounts for the bulk of the circulating antibody? A. IgA B. IgD C. IgG D. IgE

C. IgG

The only class of antibody that can cross the placenta is A. IgA. B. IgD. C. IgG. D. IgE.

C. IgG.

Which is the most efficient at initiating the classical pathway of the complement cascade? A. IgA B. IgD C. IgM D. IgE

C. IgM

Which of the following antibodies is a pentamer? A. IgA B. IgD C. IgM D. IgE

C. IgM

A physician is seeking ways to increase the fine-tuning of antibody immune responses that occurs naturally during affinity maturation. The goal is to create 'super antibodies' with intensely high affinity for antigens. She decides to use a drug that can be injected into lymph nodes that will be highly mutagenic specifically to B-cells that are undergoing activation. Is this a good idea? Why or why not? A. Introducing a highly mutagenic drug into our systems to boost immunity? Are you nuts? This is going to cause cancer! B. It WILL work, and work well. B-cells naturally have a high degree of mutation in their hypervariable region DNA as they undergo activation, and this is what leads to the possibility of affinity maturation. Boosting that activity will dramatically increase the likelihood of that process. C. It won't work. Affinity maturation is a random mutation process, followed by selection of B cells with higher affinity for the antigen in question. It doesn't matter if you increase the NUMBER of mutations-they still need to be screened for affinity to the antigen, and you can only achieve a certain level of affinity. Beyond that, and any mutations in antibody genes are just 'extra' changes without any real effect. D. The delivery method makes this impractical. It *might* work, but there are many lymph nodes around the body. During an infection, they would ALL be filled with B cells undergoing the process of affinity maturation. How would you deliver the drug to all the lymph nodes in every area of the body?

C. It won't work. Affinity maturation is a random mutation process, followed by selection of B cells with higher affinity for the antigen in question. It doesn't matter if you increase the NUMBER of mutations-they still need to be screened for affinity to the antigen, and you can only achieve a certain level of affinity. Beyond that, and any mutations in antibody genes are just 'extra' changes without any real effect.

Why would a person who has their tonsils removed be more susceptible to certain types of infections of the throat and respiratory tract? A. Tonsils produce high levels of lactoferrin, a strong natural antibacterial compound. B. Tonsils produce large amounts of interferons, natural antiviral compounds. C. Tonsils are secondary lymphoid organs-they help to provide a constant response to the microbes in the oral cavity, helping to keep them in check and preventing them from spreading to other areas. D. Tonsils are the location where T cells develop and mature. Without them, a person won't have T cells, and will be more likely to suffer from infections that would normally be eliminated by such cells.

C. Tonsils are secondary lymphoid organs-they help to provide a constant response to the microbes in the oral cavity, helping to keep them in check and preventing them from spreading to other areas.

Would a denatured antigen be expected to have the same epitopes as its native (non-denatured) counterpart? Why? A. Yes-epitopes are just a sequence of amino acids in a row, so they do not change regardless of 3D shape of the protein molecule they lie within. B. No-ALL epitopes are dependent on being in the proper original 3D conformation in the protein they arise within. Denaturing them would destroy them by destroying that conformation. C. Yes AND No-SOME epitopes are dependent on 3D conformation (conformational epitopes), while some simply depend on the primary order of amino acids (linear epitopes). So, really, it depends on the particular epitope. D. Yes-all proteins must be broken down into individual epitopes for presentation to B and T cells on MHC molecules, so each antigen protein MUST be denatured to yield ANY epitopes.

C. Yes AND No-SOME epitopes are dependent on 3D conformation (conformational epitopes), while some simply depend on the primary order of amino acids (linear epitopes). So, really, it depends on the particular epitope.

Memory cells may take the form of A. B cells. B. T cytotoxic cells. C. T helper cells. D. All of the choices are correct.

D. All of the choices are correct.

The immunoglobulin that is important in hypersensitivity reactions is A. IgA. B. IgD. C. IgG. D. IgE.

D. IgE.

The characteristic function and properties of each class of antibody is determined by the A. variable region on the light chain. B. epitope. C. constant region on the light chain. D. constant region on the heavy chain. E. variable region on the heavy chain.

D. constant region on the heavy chain.

The best possible analogy available below for the way in which variable (V), diversity (D), and joining (J) antibody gene segments get put together to create the diversity possible in hypervariable regions is A. to think of the various segments as a deck of cards-when you get dealt a hand of 5 cards, you have a very high likelihood of getting a different hand every time. The quality of the hand you have dealt will dictate whether or not you have a 'winning' hand (capable of binding to antigenic epitopes). B. to think of the various segments as the pieces of a house-you need a strong foundation first (the joining segments), followed by a frame (the diversity segments), then the interior walls (the variable segments) before the structure is complete. C. to think of the various segments as building a highway-you need to prepare the area first by clearing a path (the joining segments do this), then grade/slope the area (the diversity segments) before you can finally lay down the asphalt (the variable segments). D. to think of the various segments as a bingo game-each segment is randomly selected, but you're going to need 1 of each V, D, and J to form a functional molecule. The 'right' combination varies depending on which antigen is eventually going to be binding to the molecule (i.e. your bingo card would be the eventual antigen, and the random calling out of the number/letter combinations would be the forming of the VDJ hypervariable region).

D. to think of the various segments as a bingo game-each segment is randomly selected, but you're going to need 1 of each V, D, and J to form a functional molecule. The 'right' combination varies depending on which antigen is eventually going to be binding to the molecule (i.e. your bingo card would be the eventual antigen, and the random calling out of the number/letter combinations would be the forming of the VDJ hypervariable region).

36. "Clonal selection" and "clonal expansion" A. implies that each individual lymphocyte produces a single antibody. B. describes how the adaptive immune system can produce millions of different antibodies. C. depends on an antibody recognizing a specific epitope. D. are based on random processes. E. All of the above

E. All of the above

Ag-Ab binding may result in A. neutralization. B. immobilization. C. agglutination. D. opsonization. E. All of the choices are correct.

E. All of the choices are correct.

It would be useful if antigens were delivered directly to A. Peyer's patches. B. W Cells. C. M cells. D. red blood cells. E. Peyer's patches AND M cells.

E. Peyer's patches AND M cells.

A terrorist mad scientist develops a new blood-borne virus that will completely shut down presentation of viral epitopes on MHC molecules in the cells it infects. He produces an internet video describing it and how it will be indestructible by CD8+ cytotoxic T-cells and will kill millions (if not billions) of people. The medical community quickly denounces and discredits his plan as impossible, and the whole thing is quickly forgotten-why? A. CD8+ T-cells are not the cells that are responsible for killing virally-infected cells. The terrorist mad scientist is a misinformed idiot. B. While CD8+ T-cells ARE important for eliminating a viral infection, they are not the ONLY things that are capable of doing so. Natural Killer cells can kill virally-infected cells that have shut down MHC antigen presentation, and interferons can assist in clearing virally-infected cells. C. A blood-borne virus would not be capable of rapidly infecting millions of people, due to its difficult mode of transmission. D. B-cells would be primed right away to produce complement proteins to destroy the virus. This would prevent cells from being infected with it in the first place. His plot would be foiled. E. While CD8+ T-cells ARE important for eliminating a viral infection, they are not the ONLY things that are capable of doing so. Natural Killer cells can kill virally-infected cells that have shut down MHC antigen presentation, and interferons can assist in clearing virally-infected cells AND a blood-borne virus would not be capable of rapidly infecting millions of people, due to its difficult mode of transmission.

E. While CD8+ T-cells ARE important for eliminating a viral infection, they are not the ONLY things that are capable of doing so. Natural Killer cells can kill virally-infected cells that have shut down MHC antigen presentation, and interferons can assist in clearing virally-infected cells AND a blood-borne virus would not be capable of rapidly infecting millions of people, due to its difficult mode of transmission.

Which is involved in reacting to virus-infected cells? A. cell-mediated immunity B. T cytotoxic cells C. B cells D. MHC I E. cell-mediated immunity, T cytotoxic cells AND MHC I

E. cell-mediated immunity, T cytotoxic cells AND MHC I

Which of the following do not induce a strong immune response? A. lipids B. proteins C. polysaccharides D. nucleic acids E. lipids AND nucleic acids

E. lipids AND nucleic acids

Antigens may be processed for presentation by A. macrophages B. dendritic cells. C. erythrocytes. D. T cytotoxic cells. E. macrophages AND dendritic cells.

E. macrophages AND dendritic cells.

Class II MHC molecules are found primarily on A. macrophages. B. dendritic cells. C. erythrocytes. D. T cytotoxic cells. E. macrophages AND dendritic cells.

E. macrophages AND dendritic cells.

Which of the following is/are secondary lymphoid organ(s)? A. thymus B. spleen C. lymph nodes D. bone marrow E. spleen AND lymph nodes

E. spleen AND lymph nodes

______ or _____ determinants are a portion of antigen recognized by antibody AND may be approximately 10-25 amino acids in length.

Epitopes, antigenic

T or F: All antigens are immunogens.

F

T or F: Antibody and antigen are held to one another by covalent bonds.

F

T or F: Antibody molecules are very rigid in structure.

F

T or F: Substances with a molecular weight of less than 10,000 Daltons make good antigens.

F

T or F: T cell independent antigens lead to a memory response.

F

T or F: T cell receptors are identical to antibodies.

F

T or F: T cells are responsible for directly manufacturing antibodies.

F

T or F: The immune response is directed against an entire molecule.

F

_____ cells are used to contain bacterial infections.

Giant

The Fc region on___ interacts with complement.

IgG

Perforin is produced by

NK cells.

______ lymphoid organs are strategically located in the body AND facilitate interactions between cells.

Secondary

T or F: Gene rearrangement is responsible for the generation of the various antibody molecules.

T

T or F: IgA is the most abundant immunoglobulin made by the body.

T

CD8 cells are often

T cytotoxic cells

CD4 cells are often

T helper cells

The stimulation of B cells to divide and mature is provided by

T helper cells

Proteins that react specifically with the chemical structures in the antigen that induced them are called

antibodies

The humoral immune response involves the manufacture and use of

antibodies.

Each class of_____ is specifically defined by its amino acid sequence of the constant region of the____ chain.

antibody; heavy

Macrophages and dendritic cells are

antigen-presenting cells.

Specific chemical groups on an antigen molecule to which the immune response is directed are

antigenic determinants.

T cells and B cells are manufactured in the

bone marrow

According to the _____ _____ theory each B cell is already programmed to produce a specific antibody.

clonal selection

The chains of an antibody molecule are bonded to one another by

disulfide bonds.

The peptides presented by MHC class II peptide molecules are

exogenous antigens

An IgG molecule has two

heavy chains, light chains AND antigen binding sites.

A term synonymous with antibody is

immunoglobulin

The variable region of an antibody occurs

on all 4 chains

The cells that actually secrete antibodies are

plasma cells

Only antigen-presenting cells

produce MHC class ll molecules

T cells mature in the

thymus

The surface receptors on B and T cells both have _____ and _______ regions.

variable; constant

The scientist who received the first Nobel Prize in Medicine for his work on antibody therapy was

von Behring.