Exam 3: Set 1 Flashcards
The germinal centers found in the peripheral region of the splenic periarteriolar lymphatic sheath (PALS) and cortical regions of lymph nodes:
A. Act as primary lymphoid organs
B. Differentiate self-reactive immature B and T cells
C. Remove virally infected monocytes from the circulation
D. Are the major tissues for hematopoiesis
E. Provide an infrastructure for antigenic stimulation
E. Provide an infrastructure for antigenic stimulation
The PALS and germinal centers of lymph nodes contain large populations of B lymphocytes and plasma cells and act as secondary lymphoid organs for cells produced in the bone marrow. Self-reactive cells were previously eliminated in the thymus.
Chediak-Higashi syndrome is a rare inherited disorder in which a severe immunologic deficiency has been linked to deficiency in NK cell function as well as deficiencies in chemotactic and bactericidal function for neutrophils. Individuals with this syndrome are therefore more susceptible to bacterial infections. Which of the following best describes NK cell function?
A. Antibody-dependent cell-mediated cytotoxicity
B. Receptor signaling through CD3
C. Production of IL-2, IL-4, and IL-10
D. Killing via antigen-specific receptors
E. Recognition of Fas ligand on infected cells
A. Antibody-dependent cell-mediated cytotoxicity
There are multiple methods for direct killing of pathogens and infected host cells. NK cells are extremely effective in this process, functioning through ADCC mechanisms. The recognition is done independently of specific antigen receptors and does not require the Fas/Fas ligand interaction between effector and target cells. Although NK cells produce cytokines (interferon- and chemokines) that may assist in developing T-cell function, they do not secrete the classic TH cell cytokines.
Which of the following is considered a primary lymphoid organ?
A. Peyer patch B. Thymus C. Lymph node D. Spleen E. Appendix
B. Thymus
Both the bone marrow and thymus function as primary lymphoid organs, allowing the development of lymphocytes for functionality and ability to distinguish self from foreign antigens.
A 7-year-old child involved in a car accident developed complications leading to removal of her spleen. Which statement accurately describes the physical characteristics of the spleen?
A. The periarteriolar lymphoid sheath is composed of a germinal center surrounded by a mantle and marginal zones.
B. The spleen is a filter for lymph.
C. The red pulp contains the lymphoid tissue, which is arranged around a central arteriole as a periarteriolar lymphoid sheath.
D. Dendritic reticular cells are found in marginal centers where they present antigen to plasma cells.
E. Hassall corpuscles are located in the medulla.
A. The periarteriolar lymphoid sheath is composed of a germinal center surrounded by a mantle and marginal zones.
The spleen is a filter for blood that is histologically composed of both red and white pulp. The red pulp is made up of vascular sinusoids containing large numbers of macrophages and is actively involved in the removal of dying and dead erythrocytes and infectious agents. The white pulp contains the lymphoid tissue, arranged around a central arteriole as a periarteriolar lymphoid sheath (PALS), composed of T- and B-cell areas and follicles containing germinal centers. Dendritic reticular cells and phagocytic macrophages in germinal centers present antigen to lymphocytes; this is where B cells are stimulated to become plasma cells to produce and secrete antibodies.
Which of the following activities are most closely associated with NK cells?
A. Production of TNF-a B. Lysis of virus-infected cells C. Phagocytosis of bacteria D. Release of reactive O2 intermediates E. Production of IL-6
B. Lysis of virus-infected cells
NK cells are large granular “innate” lymphocytes that nonspecifically kill certain types of tumor cells and virus-infected cells. NK cells share many surface molecules with T lymphocytes but are able to kill in the absence of antigen-specific receptors. NK cells are especially effective against viral infected cells. NK cells can also kill via antibody-dependent cellular cytotoxic mechanisms.
A person having type O blood is best described as:
A. Having erythrocyte antigens A and B and having anti-A and anti-B antibodies
B. Having erythrocyte antigens A and B and not having anti-A and anti-B antibodies
C. Having no erythrocyte antigens and not having anti-A and anti-B antibodies
D. Having no erythrocyte antigens and having anti-A and anti-B antibodies
D. Having no erythrocyte antigens and having anti-A and anti-B antibodies
Having no erythrocyte antigens, and having anti-A and anti-B antibodies. The ABO blood groups represent important carbohydrate moieties present on erythrocytes. Individuals naturally develop antibodies (isoantibodies), which result in isohemagglutination of nonmatched antigens if incorrect blood is given to a patient. Relative to blood cell transfusions, a universal donor has erythrocytes that lack the ABO surface antigens.
A 34-year-old white female gives birth to a first child who is identified as being Rh positive. Although the mother is Rh negative, she was not treated after birth with RhoGAM (anti-Rh antibodies). During the next pregnancy, the fetus is found to have erythroblastosis fetalis (a hemolytic anemia in the fetus caused by transplacental transmission of maternal antibodies to fetal RBCs). Which isotype of maternal immunoglobulin is responsible for the hemolytic disease of the newborn?
A. IgM B. IgD C. IgE D. IgG E. IgA
D. IgG
The Rh antigens, also called Rhesus antigens, are transmembrane proteins expressed at the surface of erythrocytes, causing incompatibility between mother and fetus. An Rh-negative mother who carries an Rh-positive fetus can produce immune antibodies of the IgG isotype after birth and exposure to the fetal Rh antigens. Danger lies during subsequent pregnancy if the fetus is also Rh positive, as the mother has existing immunoglobulins to destroy fetal RBCs. IgM and IgD are early markers on developing B cells. IgE is important in type I hypersensitive responses (allergic responses), and IgA is critical for mucosal protection.
A 10-year-old male living in the subtropical region of China demonstrates clinical features of schistosomiasis that range from fever, headache, and lethargy to severe fibro-obstructive pathology leading to portal hypertension, ascites, and hepatosplenomegaly. The major immune mechanisms against this parasitic helminth are described as:
A. DTH and granulomatous reactions
B. Antibody (immune complex and cytotoxicity)
C. Antibody-dependent cell cytotoxicity and granulomatous reactions
D. DTH and antibody
E. Antibody (neutralization), CTL, and DTH
C. Antibody-dependent cell cytotoxicity and granulomatous reactions
The response to infection depends in part on both the size and complexity of the pathogen. In the case of parasitic worms, or helminths, the critical response is directed by TH2 cells that drive activation of eosinophils, basophils, and mast cells to release inflammatory mediators that limit parasitic activity and directly kill invading organisms.
A 62-year-old woman visiting Mexico on vacation was brought to the city clinic complaining of vomiting, nausea, diarrhea, and abdominal pain. The previous evening she had visited a restaurant and had consumed salsa that was contaminated with Staphylococcus aureus. Her body temperature was significantly elevated. Which combination of macrophage-derived molecules is directly involved in systemic temperature elevation (fever) during Staphylococcus aureus infection? A. IFN- γ, TNF-α B. TNF-α, IL-8 C. IFN-γ, IL-6 D. IL-1, IL-6 E. IL-1, IL-8
D. IL-1, IL-6
The proinflammatory mediators IL-1 and IL-6, along with TNF-, produced by macrophages upon infection with gram-positive organisms are responsible for both local activation events as well as systemic activity. These actions include induction of acute-phase proteins from the liver, activity on the hypothalamus to elevate body temperature, and signals to mobilize banded neutrophils from bone marrow. While other mediators are produced, such as IFN- and IL-8, they function in the local environment to stimulate adaptive functions and chemotaxis events, respectively.
A 49-year-old Venezuelan female secretary complains of persistent cough, night sweats, loss of weight, and recent blood-streaked sputum. Her chest radiograph reveals lung infiltrates, with cavitation in the upper right lobe. Acid-fast organisms grow from cultured sputum and bronchoalveolar lavage fluid, which are identified as Mycobacterium tuberculosis. Components directly involved in the mycobacterial granulomatous response include all of the following except:
A. Poorly degradable or persistent antigens B. Specialized epithelioid cells C. CD4+ Th1 cells D. Multinucleate giant cells E. Eosinophils
E. Eosinophils
Macrophages readily respond to mycobacterial infection; however, the organisms have evolved a mechanism to evade phagosome-lysosome fusion. The result is poor degradation of organisms and thus a highly persistent antigenic depot, which eventually triggers a strong delayed-type hypersensitive (CD4+ Th1 cell) response. The host eventually sequesters the infected cells by organizing pathologic granuloma structures composed of epithelioid cells and characteristic multinucleated giant cells. Eosinophils are not directly involved in this process.
A 36-year-old female presented to the emergency department reporting chest pain, shortness of breath, and cough. Her temperature was 40.10 C. Blood pressure, pulse rate, and respiratory rate were markedly elevated. Rhonchi were present over the entire left lung. A sputum sample collected revealed gram-positive diplococci in chains, many of which were seen inside polymorphonuclear leukocytes. What phenotype would be the most abundant polymorphonuclear cell found in the innate inflammatory response to this class of bacteria?
A. Eosinophil B. Transitional epithelial cell C. Basophil D. Neutrophil E. Oligodendrocytes
D. Neutrophil
Immune defenses against bacterial agents include rapid release of neutrophils from the bone marrow that are chemoattracted to the region of infection by C3a and C5a complement components (anaphylatoxins) and chemokines such as IL-8.
A 43-year-old surfer was diagnosed with advanced recurrent metastatic melanoma, characterized by concomitant downregulation of the TAP-1 gene. Which statement best characterizes the products of the TAP-1 gene?
A. Binds b2-microglobulin
B. Prevents peptide binding to MHC molecules
C. Binds to the proteasome
D. Transports peptides into the endoplasmic reticulum
E. Transports peptides into the Golgi apparatus
D. Transports peptides into the endoplasmic reticulum
TAP-1 and TAP-2 are protein members of the ATP-binding cassette transporter superfamily that drive the transport of peptide antigens across the endoplasmic reticulum for loading during endogenous assembly of the MHC class I molecules.
HLA-DR or HLA-DQ gene associations with various autoimmune diseases implicate which arm of the immune system?
A. Cytotoxic T cell (CD8+)–specific responses
B. Helper T cell (CD4+)–specific responses
C. Natural killer cell responses
D. Complement-mediated responses
E. Innate macrophage responses
B. Helper T cell (CD4+)–specific responses
HLA-DR and HLA-DQ represent two gene products of class II HLA locus. These class II MHC gene products present antigenic fragments to CD4+ T cells, allowing specificity of response. CD8+ cells recognize antigen presented via class I MHC; the innate responses do not require antigenic presentation for initiation of activity.
In a patient with thrombocytopenic purpura, cytotoxic antibodies directly mediate hemolytic anemia. This is an example of which type of hypersensitive reaction?
A. Hypersensitivity type I B. Hypersensitivity type II C. Hypersensitivity type III D. Hypersensitivity type IV E. Hypersensitivity type V
B. Hypersensitivity type II
The hypersensitivities represent different aspects of immune response that culminate in related immunopathology. The type II hypersensitivity is characterized by antibody-mediated responses that lead to cytotoxic events through deposition of complement and subsequent lysis of recognized antigens.
A 16-year-old Alaskan male experiences seasonal allergies to pollens, with clinical manifestation of runny nose, itchy eyes, and occasional wheezing. What is the molecular mechanism for mediation of this response?
A. Contact hypersensitivity B. Immune complex deposition C. Antibody-dependent cell cytotoxicity D. IgA and complement fixation E. IgE and mast cell degranulation
E. IgE and mast cell degranulation
The symptoms experienced are indicative of an acute allergic, type I–mediated hypersensitive response (anaphylactic hypersensitivity), regulated by cross-linking of allergens to mast cell receptors specific for IgE. This causes release of vasoactive amines, histamine, leukotrienes, and prostaglandins, resulting in the allergic symptoms exhibited.
