Micro HW 12
Which of the following is NOT a step that ultimately leads to antibody production?
Activation of cytotoxic T cells by helper T cells
Which of the following statements is true?
Adaptive defenses include both humoral and cellular immunity
How does adaptive immunity differ from innate immunity?
Adaptive immunity generates immunological memory and is specific to a pathogen
When do helper T-cells develop into TH1 or TH2 cells?
After proliferation into a clonal population
What is an antigen?
Any molecule that, when presented in the right context, will stimulate an immune response
TH2 cells produce cytokines that activate
B cells
Which type of cell directly binds an antigen, rather than requiring an antigen-presenting cell to first process the antigen?
B cells
Which of the following would you likely see on the surface of a human dendritic cell following phagocytosis of a bacterium?
Class I MHC with dendritic cell antigens and Class II MHC with engulfed bacteria
What would a virally infected skin epithelial cell have on its cell surface?
Class I MHC with skin cell antigens
Your patient is born without a thymus (a genetic defect known as DiGeorge Syndrome). Which of the following statements would you expect to be true for this patient?
This patient's immune system would not be able to respond to T-dependent antigens, but would have an immune response to T-independent antigens
Antibodies do all the following except
activate killing by T cytotoxic cells
A substance that may trigger an immune response, if presented in the right context is termed a(n)
antigen
All the following apply to T cells except
coordinate the humoral response by making antibodies
The human immunodeficiency virus (HIV) selectively infects any cell which carries the CD4 surface glycoprotein. Which immune function will be impaired?
stimulation of macrophage, B and TC cells
A patient antibody titer which shows an increasing level of IgM but very little IgG would likely indicate that
the patient is in the early stages of developing an immune response
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
Each antibody molecule consists of
two light and two heavy protein chains
Place the following steps of phagocytosis in the order that they occur: 1. Endosome fuses with lysozome 2. Dendritic cell engulfs Rhinovirus 3. Epitopes are attached to MHC-II 4. Digestion of the Rhinovirus 5. MHC-II plus the attached epitope move to the outside of the dendritic cell
2,1,4,3,5
Correctly order the steps involved cellular immunity: 1. The Tc recognizes the infected host cell 2. The Tc interacts with epitope presented by MHC-I on the dendritic cell 3. The Tc secretes perforin and granzyme, causing apoptosis 4. The helper T cell activates the Tc cell
2,4,1,3
Your pediatric patient recently received a DTaP vaccination, providing immunity to diphtheria, tetanus, and pertussis. If your patient is exposed to pertussis a few weeks following this vaccination, which of the results would you expect to receive when measuring the patient's antibody titers?
A rapid surge in the production of IgG antibody
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
What is meant by the clonal expansion of a B cell?
An activated B cell divides into cells that give rise to memory B cells and plasma 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
Which pair of molecules do NOT directly interact with one another?
BCR and TCR
What is the function of the CD8 receptor?
Bind to MHC molecules
Which event happens first during cytotoxic T-cell activation?
CD8 binds to MHC molecules of infected cells
A person who has AIDS contracts rare and often life-threatening infections because their helper T cell count is so low. Which of the following components of the immune response still respond to antigen despite the low helper T cell count?
Clonal selection of B cells
Which cells directly attack abnormal cells in the body?
Cytotoxic T cells
Which type of cell directly attacks infected cells?
Cytotoxic T-cells
HIV directly infects T-cells. Why is this problematic for cell-mediated immunity?
Cytotoxic T-cells begin to attack the virally infected T-cells, reducing the number of T-cells in the body
Which of the following are likely to be found on an MHC-I protein?
Damaged mitochondrial fragment
When does MHC-II loading occur?
During the fusion of vesicles containing MHC-II proteins with vesicles containing digested pathogens
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
According to the animation, antibodies directly interact with which innate defenses?
Phagocytosis and the complement system
Which structure do antigen presenting cells utilize to directly help them present bacterial antigens?
Phagolysosome
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
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
What is a feature of the small fragments presented by MHC-I proteins?
They are small peptides, roughly 8-10 amino acids long
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
T-independent antigens
are usually polysaccharides and able to bind multiple B cell receptors on a given B cell
Pregnant women are usually advised to be vaccinated against influenza to protect themselves and the baby after birth. The mother will acquire ________ immunity from the vaccine while the baby will acquire ________ immunity.
artificial active; natural passive
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
T helper cells release _____ to activate B cells.
cytokines
Advantages of isotype switching include
expanded antibody response as different isotypes predominate in different areas of the body
You conduct an experiment to test the immunogenicity of penicillin. You note that when you inject penicillin into your patient, antibody titers are at baseline. However, once penicillin is degraded in the body, it is capable of reacting with albumin, producing an elevated IgE antibody titer. Based on this experiment, penicillin would best be described as a(n) ______.
hapten
Cytotoxic T cells eliminate pathogens by
releasing chemicals which cause infected or cancerous cells to undergo apoptosis
What is the role of memory cells?
remain in the lymphoid tissue to rapidly proliferate and differentiate upon subsequent exposure to the same pathogen
Which of the following is/are (a) mechanism(s) through which antibodies increase phagocytosis?
Opsonization Agglutination Precipitation
Which of the following is not required for T cell activation?
antibody
According to the animation, B cells interact directly with
helper T cells
Which molecule triggers apoptosis?
Granzyme
What is the role of helper T cells in the adaptive immune response?
Helper T cells activate B cells and cytotoxic T lymphocytes to kill infected host cells
Immune cells that secrete cytokines and activate other immune cells are:
Helper T-cells
How do helper T-cells and cytotoxic T-cells work together?
Helper T-cells produce cytokines to activate other cells of the immune system
Antibodies are a part of which type of immunity?
Humoral
Which part of the adaptive immune response involves B cells?
Humoral
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
Your patient has an anaphylactic response to bee venom. Which of the following classes of antibodies would you expect to be elevated in the patient's serum, based on this hypersensitivity?
IgE
The most abundant antibody class in the body, found in all body fluids, is
IgG
Generally, the first antibody class made upon a primary antigen exposure is
IgM
What type of antigen typically binds to MHC I to present an MCH I-antigen complex?
Intracellular antigen
A newly-generated T cell can recognize MHCs and is not self-reactive. What is its fate?
It will migrate to the lymphoid tissues to await activation by its antigen
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
The student who caught the cold caused by this specific Rhinovirus was exposed to the exact same Rhinovirus 18 months later. What component of the immune system will protect her from getting the same cold again?
Memory B cells
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
Which of the following statements concerning T cell self-tolerance screening is true?
Once T cells pass the self-tolerance screening, they migrate to lymphoid tissues
Which of the following statements is/are true regarding T cytotoxic cell antigen elimination?
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 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
Which of the following is NOT a step used by cytotoxic T cells to kill infected host cells?
Recognition of infected host cell using its CD4 glycoprotein
Which of the following statements is true regarding superantigens?
Superantigens trigger the release of high levels of inflammatory cytokines, such as tumor necrosis factor alpha and interferon gamma by CD4 T cells
Choose the false statement.
T helper cells directly combat antigens
Which of the following defense systems would be involved in eliminating virally-infected cells?
T lymphocytes
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 of the following statements is true concerning cellular immunity?
The cellular branch of adaptive immunity is mainly organized by T helper cells and carried out by T cytotoxic cells
Which organelle assists directly with the presentation of MHC-I antigens?
The endoplasmic reticulum
Genetic mutations in the CD8a gene often result in a CD8 T cell deficiency. Which of the following scenarios would be most likely to occur in a patient with several CD8a gene mutations?
This patient would be less able to respond to certain viral invaders, such as Epstein Barr Virus
Tom has a genetic disorder in which he does not synthesize class I MHC proteins or functional NK cells. Which of the following statements would be true for Tom?
Tom would not be able to destroy virally-infected cells
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
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
Isotype switching occurs when
a B cell changes which antibody class it is producing
Mucous membranes are a part of
innate defense
The two-signal activation process for T cells includes
interaction of the T-cell receptor with the MHC-antigen complex on the APC AND binding between co-stimulatory proteins on the T cell and APC surfaces
Antigen processing and presentation
is a way for a cell to give information about its activities
All the following apply to B cells except
play a critical role in both the cellular and humoral responses
Consider a genetic mutation which causes T helper cells to be unable to respond to stimulation by the cytokines which lead to TH2 differentiation. This mutation would cause a patient to be deficient in which activity?
production of antibodies
