Q&A Hero

Q: Which of the following is a function of dendritic cells? A) antigen presentation B) plaque formation C) phagocytosis D) both phagocytosis and plaque formation

Q: Which of the following are NOT phagocytes? A) dendritic cells B) monocytes C) neutrophils D) erythrocytes

Q: The primary function of a phagocyte is to A) destroy pathogens. B) engulf pathogens. C) evade pathogens. D) both engulf and destroy pathogens.

Q: Why are rabies shots given to domestic animals yearly and not just once in the animal's lifetime?

Q: Briefly describe how B cells are activated.

Q: How do NK cells discriminate between normal, healthy cells and virus-infected or tumor cells?

Q: What are the major antigenic barriers for tissue transplantation from one individual to another?

Q: Briefly describe classical complement activation and cell damage.

Q: Why are the chances of an immune response in a patient given between 10g and 1g of an immunogen (drug) higher than a patient given higher than 1g or lower than 10g of the same drug?

Q: Briefly describe the effect of deposition of antibody or complement on the surface of a pathogen or antigen in relation to opsonization.

Q: Why must the adaptive immune system develop a capacity to discriminate between foreign antigens and host antigens?

Q: How is immune memory beneficial to a host organism?

Q: Briefly describe how a phagocyte engulfs and ingests a pathogen.

Q: IgE is found in extremely small amounts in serum.

Q: CD4 and CD8 proteins are used for in vitro tests as T cell markers to differentiate TH cells from TC cells.

Q: Self-reactive T cells are eliminated during the development of tolerance in the immune system.

Q: Class I MHC proteins are found ONLY on the surface of B lymphocytes, macrophages, and dendritic cells.

Q: HLAs are responsible for immune-mediated organ transplant rejection.

Q: The inducing antigens that react with an antibody are called heterologous antigens.

Q: TCRs recognize epitopes only after the immunogens have been partially degraded.

Q: A high-affinity antibody binds nonspecifically and loosely to antigen.

Q: Haptens CANNOT bind to or induce an immune response but CAN bind to antibodies.

Q: ALL antigens are immunogens.

Q: Tolerance is the acquired ability to make an adaptive immune response directed to self-antigens.

Q: In the adaptive immune response, effective immunity cannot be detected for several days after the first contact with the pathogen.

Q: T cell receptors on a particular T cell can recognize more than two antigens.

Q: The antigen-binding site of ALL antibodies form by interactions between the variable domains of the heavy and light chains.

Q: Nonencapsulated strains of Streptococcus pneumoniae are highly virulent.

Q: Bacterial capsules enhance the adherence of phagocytes to bacterial cell walls, thereby promoting phagocytosis.

Q: Localized infections by pyogenic bacteria often form boils or abscesses.

Q: Dead phagocytes make up much of the material of pus.

Q: Staphylococcus aureus produces carotenoids that neutralize singlet oxygen and prevent killing.

Q: Inflammation is the usual outcome of an adaptive immune response but not an innate immune response.

Q: If you were given a new necklace and developed reddening, swelling, and itching of your skin around your neck 24 hours after putting on the necklace, what reason would you give to this phenomenon? What immune cells are involved?

Q: Assume you are the procurement manager of the medical charity "Doctors Without Borders" and there was an imminent infectious disease epidemic threat in a remote village in Africa. The epidemic can be prevented by vaccinating the population of interest. However, due to bad roads and lack of fast transportation services to reach the site of interest, which type of vaccine would you purchase for this job considering the length of time it would take to reach the affected site and why? A live attenuated virus or killed virus vaccines?

Q: You are bitten by a venomous snake at a nature center. A snake handler is also bitten. You are rushed to the emergency room and given an antiserum. The snake handler does not receive treatment because he said he was exposed to venom so many times that he is immune. What is antiserum and will you have long-lasting immunity to snake venom after this? Is what the snake handler said possible or should he also receive treatment? If he does not receive treatment and is not affected, what is protecting him?

Q: Why do individuals with genetic defects that prevent neutrophil or macrophage development usually die at an early age? Be specific and detailed in your answer to demonstrate your knowledge on the role of these cells in the immune system.

Q: A woman is being treated for systemic lupus erythematosus (SLE). She has an increased risk of opportunistic infections. Based on what you know about SLE and the treatment for it, propose why she has an increased risk of opportunistic infections.

Q: A child is stung by a bee at the beginning of the summer and has mild swelling and itching at the site of the sting. In late summer, the child is stung again, but this time rapidly develops anaphylaxis and is diagnosed with type I hypersensitivity to bee venom. If the child is allergic to bee venom, why was there no reaction after the first bee sting? What specifically happened after the first sting that led to the allergic reaction?

Q: Are superantigen reactions beneficial or harmful to the host? What is different about a superantigen reaction compared to normal antigen-host cell interactions?

Q: Differentiate between T-cytotoxic (TC)cells and T-helper (TH) cells.

Q: What is antigen presentation? Why is antigen presentation important for long-term immunity?

Q: What is tolerance, and why must the adaptive immune system exhibit tolerance?

Q: Explain why an individual lymphocyte clone that interacts with a specific LPS constituent of Salmonella will not react with the LPS of other bacteria.

Q: How do phagocytes interact speedily and effectively with pathogens?

Q: Compare and contrast the origin and roles of B cells and T cells.

Q: How does the body respond when it first encounters a foreign particle or bacterial pathogen?

Q: Staphylococcus aureus and Streptococcus pyogenes produce exotoxins known as superantigens that bind to a site on the TCR that is outside the antigen-specific TCR binding site.

Q: A toxoid is an attenuated form of a toxin that retains both its antigenicity and toxicity.

Q: Superantigens activate more T cells than a normal immune response.

Q: Men are 20 times more likely to develop systemic lupus erythematosus (SLE) than women.

Q: Symptoms of delayed-type hypersensitivity may appear several hours to days after secondary exposure to the eliciting antigen.

Q: Antihistamines are used to treat some allergic symptoms because they neutralize the histamine mediators that cause rapid dilation of blood vessels and contraction of smooth muscles that initiate the symptoms of systemic anaphylaxis.

Q: DNA vaccines are bacterial plasmids that contain cloned DNA with an antigen of interest are unlike attenuated vaccines because there is no chance of causing disease.

Q: A recombinant-vector virus would still be effective if the vaccinia virus is unable to express the cloned gene as an antigenic protein.

Q: Vaccines can be developed from synthetic peptides.

Q: Infants acquire natural passive immunity from maternal antibodies transferred across the placenta or in breast milk.

Q: Individuals with severe combined immunodeficiency syndrome (SCID) have a genetic defect that prevents proper formation and expression of immunoglobins and T cells and therefore do not have adaptive immunity.

Q: Phagocytes interact speedily and effectively with pathogens because they have evolved specialized molecules called pattern recognition receptors (PRRs) that interact directly with PAMPs.

Q: An individual can receive injections of an antiserum or purified antibodies derived from an immune individual.

Q: People with aggamaglobulinemia do not make protective antibodies and suffer from recurrent, life threatening viral infections, but can develop normal immune responses to bacteria.

Q: TH2 cells interact directly with the pathogens.

Q: The T cell, with its T cell receptor, can recognize antigens only when the antigens are complexed with self proteins known as major histocompatibility complex found on host cell surfaces.

Q: In adaptive immunity, pathogen specific receptors are produced in large numbers only after exposure to the pathogen or its products.

Q: Dendritic cells are phagocytes with antigen-presenting properties.

Q: All gram-negative bacteria have lipopolysaccharides in their outer membranes.

Q: Antibodies are soluble proteins produced by T cells.

Q: Monocytes and granulocytes are the two lineages of myeloid cells.

Q: Blood serum contains cells and clotting proteins.

Q: Anticoagulants promote the clotting of blood.

Q: Erythrocytes are the most numerous cells in human blood.

Q: Immunity results from the actions of cells that circulate throughout the body, primarily through the blood and lymph.

Q: Superantigens produce a harmful immune response because A) they activate too many T cells, causing excessive inflammation and cell damage. B) they initiate a type I allergic response resulting in excessive inflammation. C) too many phagocytes are activated and destroy host tissue. D) a strong immune response is necessary to protect the host from the pathogen.

Q: Which of the following is NOT an autoimmune disease? A) systemic lupus erythematosus B) anaphylaxis C) juvenile diabetes D) multiple sclerosis

Q: What are the primary chemical mediators released from mast cells during a type I hypersensitivity reaction? A) antibodies B) interleukin I and tumor necrosis factor C) histamine and serotonin D) cytokines

Q: What is the drawback of live attenuated vaccines? A) They require more secondary reimmunizations than other vaccines. B) They are not effective in adults. C) They do NOT provide a long-lasting secondary immune response. D) They can cause disease in some immunocompromised individuals.

Q: Why are secondary or "booster" reimmunizations given? A) Secondary immunizations are necessary for an innate immune response. B) Secondary reimmunizations produce a secondary immune response and boost antibody titers. C) Secondary reimmunizations produce a phagocytic immune response that is longer lasting than the primary immune response. D) Frequent secondary reimmunizations are needed because the immune system doesn't remember antigens for more than a few years.

Q: Which of the following can be used in creating a vaccine? A) attenuated bacteria B) inactivated viruses C) recombinant proteins D) attenuated bacteria, inactivated viruses, or recombinant proteins

Q: An attenuated strain of a pathogen A) has lost its virulence, but may be used to create a vaccine. B) has changed its antigens to avoid an adaptive immune response. C) is more virulent than the regular strains and may cause septic shock. D) is an extracellular pathogen that will be cleared by innate immunity.

Q: The purposeful artificial stimulation of active immunity to a particular infectious disease is known as A) immunodeficiency. B) hypersensitivity. C) immunization. D) opsonization.