HMX Immunology Final Exam with 100% Correct Answers .

HMX Immunology Final Exam with 100% Correct Answers . One of the most important advances in surgery arrived near the end of the nineteenth century. The British surgeon Joseph Lister hypothesized that using techniques to sterilize surgical tools and clean the skin at the site of the incision would reduce surgical site infections. Years later, Dr. Lister wrote this: "Nothing was formerly more striking in surgical experience than the difference in the behavior of injuries according to whether the skin was implicated or not. Thus, if the bones of the leg were broken and the skin remained intact, the surgeon applied the necessary apparatus without any other anxiety than that of maintaining a good position of the fragments, although the internal injury to bones and soft parts might be very severe. If, on the other hand, a wound of the skin was present, communicating with the broken bones, although the damage might be in other respects comparatively slight, the compound fracture, as it was termed, was one of the most dangerous accidents that could happen...It was clearly in some way due to the exposure of the injured parts to the external world." - Lister, J. Address By the President. Science 4, 409-429 (1896). This quote highlights the critical role of what component of the innate immune system in defense against microbes? - Correct Answer-Epithelial barriers Which of the cells below are tissue resident sentinel cells - Correct Answer-mast cell, macrophage, dendritic cell Which of the cells below are circulating blood cells that will enter tissue in response to inflammation? (select two answers) - Correct Answer-Neutrophils Monoctyes Mast cell - Correct Answer-Cells that release chemicals (such as histamine) that promote inflammation. Neutrophil - Correct Answer-Most abundant leukocyte Phagocyte that rapidly dies after ingesting microbe macrophage - Correct Answer-Phagocyte that cleans up apoptotic cells When a monocyte moves into the tissues, it changes rapidly and becomes a ____________ . - Correct Answer-macrophage Leukocyte adhesion deficiency (LAD) is a genetic defect that leads to recurrent infections in the tissue and severe problems with wound healing. LAD patients also develop severe gingivitis (infections and inflammation of the gums). In LAD, leukocyte migration into tissues is severely impaired. All of these problems can be traced back to a genetic defect. Of the genetic defects listed below, which is the most likely cause of LAD? - Correct Answer-A mutation that introduces a stop codon into a gene that encodes part of the LFA-1 molecule (leading to a truncated protein). Toll-like receptors for bacterial PAMPs are found on/in the - Correct Answer-cell membrane There are a few different proteins that act as inhibitors of NF-kB. There is a very rare genetic disease in which one of these proteins, IkBα, is mutated. The mutation substantially alters the stability of the IkBα protein. In patients with this disease, IkBα protein expression does not change in response to stimuli that cause IkBα degradation in healthy individuals. Consider the biological role of NF-kB inhibitors. What are the most likely symptoms of this genetic defect? - Correct Answer-Immunodeficiency with a susceptibility to bacterial infections. The complement pathway initiated by host proteins that bind to microbial sugars is called the ____________ pathway. - Correct Answer-lectin pathway ssRNA (single-stranded RNA) and dsDNA (double-stranded DNA) are present in mammalian cells. Why don't our plasmacytoid dendritic cells activate an innate immune response against these self nucleic acids that are necessary for normal cellular function? - Correct Answer-The TLRs that recognize ssRNA and dsDNA are sequestered in endosomes. How can the antiviral state be propagated in the absence of immune cells? - Correct Answer-Type I IFNs are produced by infected epithelial cells; this induces anti-viral biochemical changes in the same cell and adjacent cells. A child presents with recurrent bacterial infections. Of the genetic defects described below, what is the most likely cause of her disease? - Correct Answer-A mutation in the C3 gene that renders the C3 protein nonfunctional. ____________ is the process by which something that is not otherwise recognized as a pathogen is coated with proteins that make it more recognizable to the immune system. - Correct Answer-Opsonization The majority of the symptoms of tetanus infection are caused by the tetanus toxins, chiefly tetanospasmin. Tetanospasmin is one of the deadliest toxins known; even very small doses (nanograms) can be lethal. It targets the nerves, causing severe muscle spasms. The tetanus vaccine consists of inactivated tetanus toxin; the vaccine is highly effective for preventing tetanus. Inoculation with the tetanus vaccine leads to the production of protective antibodies. How do these antibodies prevent tetanus? - Correct Answer-Neutralization Streptococcus pneumoniae is an extracellular bacterium that is a leading cause of bacterial pneumonia and meningitis, particularly in children and the elderly. Fortunately, most cases of S. pneumoniae can be prevented with a vaccine that contains components of the bacterial capsule. The vaccine is known to lead to the production of antibodies that recognize intact bacteria. What are the most likely mechanisms activated by these antibodies that result in protection against S. pneumoniaeinfection? (select two answers) - Correct Answer-The key is that S. pneumoniae is an extracellular bacterium. The vaccine elicits a humoral immune response, which generates antibodies that bind to the surface of the bacterium. The antibodies bound to bacteria can activate complement (direct killing of the bacteria) and opsonization followed by phagocytosis. ADCC is usually directed against viral proteins displayed on the surface of cells. It is conceivable that antibodies could neutralize the function of bacterial components, but direct killing by complement and phagocytosis are the best-characterized mechanisms for eliminating extracellular bacteria. There is strong interest in developing a vaccine that would prevent human immunodeficiency virus (HIV) infection or substantially reduce viral loads in a person with HIV. HIV infects immune cells by binding to a receptor called CD4 on the surface of those cells. Laboratory studies have identified rare antibodies that bind to intact HIV viral particles and effectively control the virus in certain individuals. Structural studies revealed that some of these antibodies bind to a protein on the surface of HIV at the same location where this protein binds to CD4. What is the most likely mechanism of action of these antibodies? - Correct AnswerNeutralization How many distinct peptide chains are found in a single molecule of IgG? - Correct Answer-Each IgG antibody is comprised of two heavy chain and two light chain peptide chains joined by disulfide bridges. How many distinct binding sites are found in a single molecule of IgG? - Correct Answer-Two Which of the following antibodies is protected from proteases that are commonly found in the gut? - Correct Answer-IgA Neutrophils, NK cells, and macrophages all have receptors for the __________________ portion of the antibody, and use this to recognize antigens that are coated with antibodies. - Correct Answer-Fc Antibodies can cause disease by: - Correct Answer-a combination of complement fixation and opsonization, leading to frustrated phagocytosis and inflammation-mediated damage forming complexes in the circulation that can deposit in vessel walls and potentially trigger further immune activation recognizing antigens that are part of our own cells, leading to opsonization and destruction by phagocytes recognizing antigens that are part of our own cells, leading to complement activation Which of the following is an example of an autoimmune disease caused by antibodies that interfere with the function of a self protein? - Correct Answer-Antibodies bind to receptors for a neurotransmitter, leading to paralysis. Which of the following are components of an adaptive immune response to pathogen? (Select two answers.) - Correct Answer-clonal selection by specific antigen clonal expansion A researcher suspects that a certain leukocyte population plays a role in a particular disease. She studies mice with a genetic defect that leads to the development of the disease in young mice. She decides to test her hypothesis by surgically removing the thymus from newborn mice, then observing these mice for disease progression. What leukocyte population does she suspect contributes to the development of the disease? - Correct Answer-T cells Which of the cells below are granulocytes? (Select two answers.) - Correct AnswerGranulocytes are a group of cells with secretory granules, they include neutrophils, basophils and eosinophils. Which of the following cells would fail to develop due to a genetic defect in the enzymes involved in V(D)J recombination? (Select two answers.) - Correct Answer-T cells and B cells express receptors that undergo V(D)J recombination and other processes to generate an enormous amount of receptor diversity. What would be the most common symptom in humans with the genetic defect described above? - Correct Answer-high susceptibility to infections Which of the following would be a logical approach to curing SCID? Please read the explanation to the previous question for a definition of SCID. - Correct Answer-transplantation of bone marrow from a normal donor Which of these statements accurately describes the differences between B cells and T cells? - Correct Answer-B cell receptors can recognize virtually any antigen, T cell receptors only recognize peptides displayed on MHC molecules. Which of the following does NOT contribute to the diversity of different antibodies? - Correct Answer-millions of different antibody genes are inherited from each parent Dendritic cells express - Correct Answer-MHC, B7-1, B7-2 Helper T cells express - Correct Answer-CD4, CD28, CTLA-4, PD-1 Which of the molecules, below, is required for both naive T cells and activated dendritic cells (DCs) to migrate to the lymph node? - Correct Answer-CCR7 A T cell in the lymph node recognizes a peptide-MHC complex and T cell receptor signaling begins. The T cell enters a state of anergy. How might this have happened? (select two answers) - Correct Answer-CTLA-4 on the T cell binds to B7 with high affinity, blocking CD28 signaling. The antigen presenting cell does not express any costimulatory molecules. MHC class I - Correct Answer-Proteasomes.