Microbiology Exam #4

Which event happens first during cytotoxic T-cell activation?

CD8 binds to MHC molecules of infected cells

Which of the following is not a proposed explanation for the development of autoimmunity?

Certain antigens in a person's diet could trigger the production of antibodies that cross-react with host tissues.

Which of the following describes the classical pathway of complement activation?

Complement proteins activate when antibodies bind to a pathogen.

Antipyretics such as ibuprofen and acetaminophen work in which of the following manners?

Decrease production of prostaglandins

The hygiene hypothesis proposes which of the following?

Decreasing diversity of our normal flora from increased antibiotic usage and changes in diet and lifestyle may lead to increased allergies and autoimmune disorders.

Which of the following statements concerning desensitization therapy is true?

Desensitization therapy encourages plasma cells to produce IgG antibodies against the allergen.

When does MHC-II loading occur?

During the fusion of vesicles containing MHC-II proteins with vesicles containing digested pathogens

Which of the following scenarios would be most likely to lead to graft-versus-host disease?

A bone marrow is transplanted from an older, unaffected sibling to a younger sibling affected with severe combined immunodeficiency.

Which of the following scenarios would result in long-term immunity?

A healthy individual receiving an MMR vaccination An otherwise healthy individual developing antibodies against Epstein-Barr virus following a case of mononucleosis

Which branch of the immune system produces antibodies?

Adaptive humoral response

Choose the false statement about immune responses.

Adaptive immune responses are always the same, regardless of the threat encountered, while innate immune responses are not.

Which of the following as an example of an autoimmune disorder?

After infection with Zika Virus, your patient develops Guillain-Barré syndrome. Following an untreated case of strep throat, your patient develops rheumatic heart disease. Your juvenile patient develops Type I diabetes mellitus.

When do helper T-cells develop into TH1 or TH2 cells?

After proliferation into a clonal population

Which of the following scenarios is most concerning for development of hemolytic disease of the newborn?

An Rh- mother pregnant with an Rh+ fetus

What is the primary benefit of vaccination?

An immune response will occur quicker upon future exposure to the pathogen.

What makes agglutination by antibodies possible?

Each antibody has at least two antigen-binding sites.

How can a sufficient humoral immune response occur if a plasma cell only lives for a few days?

Each plasma cell can produce up to 2000 antibodies every second.

Which of the following measures can be used to diagnose allergies?

Elevated IgE titers within the patient's serum to a specific allergen Large wheal and flare lesion following a skin prick test

Which of the following statements is/are ways in which fever is protective?

Fever enhances antiviral properties of interferon. Fever increases phagocytic efficiency. Fever limits the growth of heat-sensitive pathogens.

What is an antigen?

Any molecule that, when presented in the right context, will stimulate an immune response

Which of the following statements best describes the hygiene hypothesis as it relates to allergies?

As a result of increased antibiotic usage and cleaner foods and beverages, our normal gut microbiota has shifted, resulting in increased hypersensitivities in developed countries.

Which type of vaccine could possibly cause a person to develop the disease?

Attenuated live vaccine

Which type of cell directly binds an antigen, rather than requiring an antigen-presenting cell to first process the antigen?

B cells

TH2 cells produce cytokines that activate

B cells.

Which of the following statements regarding B lymphocytes is/are true?

B lymphocytes are both produced and mature in the bone marrow. Once activated, B lymphocytes have the ability to produce antibodies.

A patient with the antigens A and RH+ would not be able to receive blood from which of the following?

B+

What is the function of the CD8 receptor?

Bind to MHC molecules

What is the function of boosters?

Boosters are injections that are given periodically to maintain immunity.

Which of the following does not describe adaptive immunity?

generalized responses that don't vary based on the pathogen being fought

Which of the following is NOT an autoimmune type IV hypersensitivity?

graft-versus-host disease

In a recombinant vector vaccine, genetic material from a pathogen is placed into a ________ and introduced to human cells.

harmless virus or bacteria

The influenza vaccine is an example of a(n)

inactivated killed vaccine.

Which of the following allergies and treatments is mismatched?

insect bite/sting allergy: continued preemptive treatment with an injected antibody preparation that ties up the patient's IgE antibodies

Antigen processing and presentation

is a way for a cell to give information about its activities.

Chronic inflammation

is not useful or protective and promotes atherosclerosis, cancers, and neurodegenerative disorders.

The cellular branch of adaptive immunity

is organized by T helper cells and carried out by T cytotoxic cells.

A patient that experiences a tuberculin skin test reaction is experiencing which class of hypersensitivity reactions?

type IV

Which of the following hypersensitivities are T cell-mediated responses against self-antigens or otherwise harmless antigens?

type IV hypersensitivities

Which cell type is the most numerous white blood cell in circulation, is the first leukocyte recruited from the bloodstream to injured tissues, and releases potent antimicrobial peptides?

neutrophils

Although antivenom can save lives, it can also cause what type of reaction in certain patients?

nonautoimmune type III hypersensitivity

Which of the following is an outcome of complement activation?

opsonization, cytolysis, and inflammation

All the following apply to B cells except

play a critical role in both the cellular and humoral responses.

The general goal of first-line defenses is to

prevent pathogen entry.

Which of the following is not a main goal of inflammation?

produce localized heat and swelling in an effort to denature key bacterial proteins

The aspect of the immune response that vaccines are based on is

production of memory cells and high antibody titers from pathogen exposure.

In contrast to a primary immune response, immunological memory

provides a rapid reactivation of both cellular and humoral responses including generating higher antibody titers and antibodies with increased affinity for its antigen.

Which of the following features are shared between both innate and adaptive immunity?

recognize diverse pathogens, eliminate identified invaders, and discriminate between self and foreign antigens

Antimicrobial peptides can do all of the following except

regulate body temperature.

What is the role of memory cells?

remain in the lymphoid tissue to rapidly proliferate and differentiate upon subsequent exposure to the same pathogen

What are cytokines?

signaling proteins that help cells communicate with each other, initiating and coordinating immune actions

Allografts are

similar to the host, but not genetically identical.

Adjuvants appear to work by

stimulating cytokine release and encouraging the uptake and processing of antigens by dendritic cells.

Which of the following statements is/are true regarding T cytotoxic cell antigen elimination?

Following apoptosis by cytotoxic T cells, macrophages and natural killer cells clear the dead cells. Interferons released by infected or cancer cells attract and activate cytotoxic T cells, while cytokines released by the cytotoxic T cells attract natural killer cells and macrophages. Once the threat has been detected by the T cell receptor, the cytotoxic T cell releases perforins that form pores in the target cell and granzymes, which enter through pores to trigger apoptosis.

Which of the following statements describes the purpose of gene shuffling?

Gene shuffling generates an enormous repertoire of antigen receptors during lymphocyte development.

Which of the following is not a type I hypersensitivity reaction?

Goodpasture syndrome

Which of the following statements accurately describes the way(s) in which granulocytes and agranulocytes differ?

Granulocytes consist of neutrophils, mast cells, eosinophils, and basophils, whereas agranulocytes consist of lymphocytes, dendritic cells, and monocytes. Granulocytes have granules in their cytoplasm that are visible with light microscopy, whereas agranulocytes do not have granules in their cytoplasm.

Which molecule triggers apoptosis?

Granzyme

Which of the following acts as a proinflammatory factor?

Histamine

________ reactions are inappropriate responses against a threat that lead to immune-based pathologies such as allergy and autoimmunity.

Hypersensitivity

The branches of adaptive immunity are

the cellular response and the humoral response.

Place the stages of adaptive immunity in order from first to last. I. Antigen elimination and memory II. Lymphocyte activation III. Antigen presentation IV. Lymphocyte proliferation and differentiation

III, II, IV, I

Choose the false statement.

IgG binds to the surface of mast cells and basophils.

What is graft-versus-host disease?

Immune system cells in transplanted bone marrow attack the body of its new host.

Which of the following statements is true concerning the alternative complement cascade?

In the alternative complement cascade, complement proteins directly interact with the invading agent.

Which of the following statements accurately describes innate immunity?

Innate immunity has an immediate response to antigens. Innate immunity has the capacity to distinguish foreign versus self.

Which of the following mechanisms occurs in a patient suffering from systemic lupus erythematosus?

Insoluble antigen-antibody complexes form and deposit in tissues, attracting complement, which in turn activates inflammation cascades and recruits inflammation-promoting leukocytes.

What is the difference between an intolerance and an allergy?

Intolerances tend to have a delayed onset of symptoms, while allergic reactions occur rapidly.

What type of antigen typically binds to MHC I to present an MCH I-antigen complex?

Intracellular antigen

Which of the following is part of the second line of defense?

Leukocytes Molecular factors such as chemokines

Why are leukocytes so central to second-line molecular defenses?

Leukocytes produce second-line molecular defenses.

Based on the animation, T cells recognized the antigen displayed by what protein of the B cell?

MHC

What is the role of MHC I in the immune response?

MHC I is found on all body cells except red blood cells and presents a sample of cellular proteins, including those of any intracellular pathogens, to T cells.

Which statement is not true about MHC II?

MHC II interacts with both the CD4 and CD8 receptors on T helper and T cytotoxic cells.

Which proteins on the antigen-presenting cell are recognized by the helper T-cell?

MHC proteins

Which of the cells listed below can present antigens on Class II MHC proteins?

Macrophages

When a person has previously been vaccinated against a viral pathogen, which cells are activated if that same pathogen re-enters the host's cells months or years later?

Memory cytotoxic T cells

Which of the following statements concerning natural killer cells is true?

Natural killer cells provide protection against viruses, bacteria, parasites, and tumors.

Why would a body cell that is not a phagocyte need to present antigens?

Non-phagocytic body cells can become infected with a virus.

Where are MHC molecules located on a cell?

On the surface of the cell

While hiking, you sprain your ankle. Which of the following signs and symptoms of inflammation should you observe?

Pain Swelling

Antibodies are secreted from which type of cell?

Plasma cells

What is produced by the process of clonal expansion?

Plasma cells and memory B cells

What is the role of plasma cells in humoral immunity?

Plasma cells produce antibodies.

Herd immunity describes

the protection conferred to non-immunized people when a sizable portion of the rest of the population is immunized.

A drawback of all inactivated vaccines is that

they are quickly cleared from the body, limiting antigen exposure.

Which of the following are primary lymphoid tissues?

thymus and bone marrow

Conjugate vaccines which link the target antigen to a more immunogenic antigen are usually for

vaccines against bacterial polysaccharide antigens.

The Hepatitis B vaccine is which type of vaccine?

Subunit vaccine

Choose the false statement.

T helper cells directly combat antigens.

An antigen that is potent enough to activate a B cell on its own is known as

T-independent antigens.

Which T cell class is incorrectly matched with its description?

TC: attack other T cells during self-tolerance screening

Which receptor on the helper T-cell recognizes the specific antigen from an antigen-presenting cell?

TCR

Natural killer cells are activated by

TH1 cells.

Which of the following most accurately describes how a pathogenic bacterium might be affected by antibodies?

The antibodies may block proteins necessary for binding the pathogen to the host, may opsonize the bacterium, or may agglutinate bacteria.

Which organelle assists directly with the presentation of MHC-I antigens?

The endoplasmic reticulum

Which of the following is an example of a mechanical barrier?

The mucociliary escalator sweeps mucus away from the lungs and toward the mouth.

What is apoptosis?

The process of programmed cell death.

Which statement provides the best explanation of the need for self-tolerance screening of lymphocytes?

The process which generates the vast array of diverse antigen receptors is a random process that could produce receptors which will bind to the body's own tissues.

Which of the following best characterizes clonal selection?

The production of identical B cells producing the same antibody

Which of the following statements concerning the secondary response is true?

The secondary response results in production of antibodies with a higher affinity for the antigen.

What is the hallmark of a conjugated vaccine?

These vaccines contain weakly antigenic elements plus a more potent antigenic protein.

What is a feature of the small fragments presented by MHC-I proteins?

They are small peptides, roughly 8-10 amino acids long.

Which of the following statements about type III hypersensitivities is false?

They develop when IgD or IgE antibodies bind to insoluble targets.

How do phagocytes communicate to other cells what they have captured?

They present antigens from engulfed foreign cells.

What is the fate of activated cytotoxic T-cells?

They proliferate into a clone of cells specific to the same antigen; some of these cells then differentiate into long-lived memory T-cells, while others mature to attack infected cells.

What is edema?

tissue swelling

The amount of antibody present in the blood is termed the antibody ________.

titer

Allergies are classified as:

Type I hypersensitivities

Which of the following types of hypersensitivity reactions involves production of antibodies?

Type III hypersensitivity Type II hypersensitivity Type I hypersensitivity

Which of the following hypersensitivity classes is properly listed with its description?

Type III, immune complex

Which of the following statements regarding type IV hypersensitivities is true?

Type IV hypersensitivities are delayed and typically manifest slowly over 12--72 hours after the stimulating antigen is encountered.

Why are type IV hypersensitivities called delayed hypersensitivity reactions?

Type IV reactions manifest slowly over 12-72 hours after the stimulating antigen is encountered.

Which of the following statements accurately differentiates the adaptive immune system and the innate immune system?

Unlike the innate immune system, the adaptive immune system is characterized by memory and specificity. Unlike the innate immune system, the adaptive immune system includes both a cellular and humoral response.

What does a vaccine contain?

Weakened or killed pathogen or parts of a pathogen

What is the role of B cell receptors (BCRs) and T cell receptors (TCRs) in the immune response?

to recognize specific epitopes of an antigen

How is the immune system able to recognize a limitless number of different antigens and epitopes?

While each lymphocyte carries receptors that recognize only one type of epitope, the immune system produces a wide variety of lymphocytes each of which carries unique receptors.

In 1984, in one of the most famous cross-species transplantations, a baboon heart was transplanted into an infant (Baby Fae). This surgery is an example of which of the following types of grafts?

Xenograft

Which of the following scenarios is an example of a primary immunodeficiency?

Your patient is born with agammaglobulinemia, a genetic condition that leads to decreased antibody production.

A major factor in the re-emergence of vaccine-preventable diseases in the early 21st century has been

a flawed research study incorrectly linking vaccination to autism was published in the late 1990s.

A DNA vaccine involves placing genes into a plasmid and introducing the plasmid into human cells. Human cells then transcribe and translate the genes to produce antigen which immunize the recipient. What is the source of the genes being introduced?

a pathogen

Antibodies do all the following except

activate killing by T cytotoxic cells.

Which of the following is not a hallmark sign of primary immunodeficiencies?

acute

A vaccine additive which enhances the body's natural immune response is called a(n)

adjuvant

Which of the following class of hypersensitivity reactions is not associated with autoimmunity?

allergies

What two types of patients help demonstrate that cancer can be considered a failure of the immune system?

transplant patients and HIV/AIDS patients

Which of the following are the three phases of inflammation?

vascular changes, leukocyte recruitment, and resolution

Which of the following would not cause serum sickness?

anti-inflammatory drugs

Which of the following are used to treat serum sickness?

anti-inflammatory drugs and antihistamines

A substance that may trigger an immune response, if presented in the right context is termed a(n)

antigen.

Which of the following is an example of a chemical barrier?

antimicrobial peptides

The difference between T cell activation by normal antigens and T cell activation by superantigens is that superantigens

are not processed and presented by APCs and cause nonspecific activation of many T cells at once, including those that would not normally recognize the antigen.

Live attenuated vaccines

are the closest to the actual infectious agent encountered in nature and stimulate potent immune responses to multiple antigens on the pathogen.

T-independent antigens

are usually polysaccharides and able to bind multiple B cell receptors on a given B cell.

What are the two categories of second-line defenses?

assorted molecular factors and leukocytes

Which is not a step in the process of B cell activation by a T-dependent antigen?

binding of the antigen to a T helper cell receptor

Autoimmune disorders are

chronic conditions that develop from the immune system attacking healthy self-tissues that should normally be left alone.

Which of the following can cause primary immunodeficiencies?

congenital immunodeficiency

All the following apply to T cells except

coordinate the humoral response by making antibodies.

plasma cells and memory cells

cytokines

Which cell type works to prevent our immune system from attacking self and from over-reacting to non-threatening substances, is abundant in tissues next to body openings, and phagocytizes a broad range of antigens?

dendritic cells

Which of the following pairs is not an example of a cytokine and its function?

eicosanoids: promote the replication and gathering of leukocytes

Which of the following is not a cardinal sign of inflammation?

fever

Secondary lymphoid tissues

filter lymph and sample surrounding body sites for antigens which are brought into contact with the leukocytes that reside in secondary lymphoid tissues to stimulate an immune response.

Localized anaphylaxis tends to feature isolated symptoms such as

watery eyes, a runny nose, or a confined rash.

In what situation is hemolytic disease of the newborn a life and death situation?

when an RH- mom is pregnant for the second time with an RH+ fetus

What is the general classification used to categorize leukocytes?

whether or not leukocytes have granules in their cytoplasm that are visible when stained and then viewed by light microscopy