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One health risk associated with excessive cytokine release is the chance of


A) severe tissue damage.
B) cytokines destroying antibodies.
C) damage to virally infected cells.
D) inactivating mitosis.

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Helper T cells display the surface antigen ________.

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Describe the function of the major histocompatibility complex (MHC).

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The major histocompatibility complex (MH...

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MHC molecules are required for


A) B cell activation.
B) phagocytosis of microbes.
C) T cell activation.
D) proteasome degradation of viruses.

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C

Rebecca developed measles as a young child.As a teenager,she is reexposed to the measles virus during an outbreak at her high school.Explain the immune response that will most likely prevent Rebecca from experiencing any signs or symptoms of measles.

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Exposure to the measles virus as a child...

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How would you expect an injection of killed or attenuated Salmonella typhi,the causative agent of typhoid fever,to protect an individual?


A) The injection would cause the individual to have a mild case of typhoid fever, but would protect against future cases of typhoid fever.
B) The injection would provide antigens recognizable by the immune system and memory cells would form to prevent typhoid fever in the future.
C) The injection would provide cross-protection to prevent several diseases caused by different bacteria.
D) The injection would provide the individual with premade antibodies capable of binding to and inactivating Salmonella typhi.

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The second signal required for TC activation is


A) binding of a CD28 molecule on the T cell to a B7 protein on an antigen-presenting cell.
B) secretion of the cytokine IL-2 from a TH1 cell.
C) binding of a CD8 molecule on the T cell to an antigen-MHC I complex on an antigen-presenting cell.
D) secretion of the cytokine IL-1 from a TH0 cell.

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Class switching is the process in which


A) B cells switch from producing IgM of IgD to producing IgE, IgG, or IgA.
B) formed IgM antibody pentamers break apart into IgM monomers.
C) antibody released from the surface of a B cell switches to a different heavy chain.
D) higher-affinity antibodies are produced upon repeated exposure to the same antigen.

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The process illustrated in this figure is best described as The process illustrated in this figure is best described as   A)  capping. B)  T-cell-dependent activation. C)  class switching. D)  clonal selection.


A) capping.
B) T-cell-dependent activation.
C) class switching.
D) clonal selection.

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Which of the following statements correctly describes the molecules that elicit an immune response?


A) Antigens are small molecules that must be bound to an immunogen to elicit an immune response.
B) Small segments of an antigen that elicit an immune response are called epitopes.
C) Haptens are proteins that elicit the synthesis of antibodies and are also known as antigens.
D) Immunogens are small segments of antigens that are recognized by the immune system.

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Describe the two-step molecular process required to activate TH0 cells.

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TH0 cells with CD4 molecules are able to...

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CASE HISTORY Luke,a 24-year-old mechanic from Egypt Beach,Massachusetts,was feeling run-down.Over the past month he had not been eating much and was always tired,and he recently noticed pain just under his right rib cage.His urine had recently turned the color of tea,and his wife noticed that the whites of his eyes were taking on a yellowish tinge.Luke finally went to the doctor,who suspected Luke had cirrhosis,a liver disease.This preliminary diagnosis was based on Luke's symptoms.Luke's abdominal pain was located over the liver,and the color of his urine and the jaundice evident in his eyes all pointed toward liver disease.Luke did not drink alcohol and had never left the country,but when questioned,Luke admitted to taking intravenous drugs.The doctor suspected hepatitis and ordered a series of blood tests to check for the presence of liver enzymes,antihepatitis antibodies,and hepatitis DNA or RNA in his blood.The tests revealed a high level of hepatitis B viral DNA.Luke had hepatitis B disease. How can cellular immunity,which normally protects the body against known viral and other intracellular pathogens,be harmful to Luke,given his diagnosis? Consider how T cells recognize and respond to cells displaying foreign antigen.

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Most cellular damage associated with hepatitis B is the direct result of the attack of cellular immune responses against infected liver cells.This tissue damage leads to the signs and symptoms associated with the disease.

CASE HISTORY Nathan was a ten-month-old male who had suffered much in his short life.Since birth he had experienced recurrent serious extracellular bacterial infections,all of which were resolved by antibiotic treatment.On Christmas Day,Nathan's mother discovered he had another high fever and a nonproductive cough (no mucus) .He was also having trouble breathing.Fearing one more serious infection,Nathan's mother rushed him to the hospital.An X-ray showed the lung infiltrate with the appearance of ground glass.A tube was placed through Nathan's nose and into his lung,and a solution was used to wash out deep-lung contents for microscopic examination (bronchoalveolar lavage) .The fluid yielded microscopic organisms.Nathan was hospitalized with pneumonia caused by Pneumocystis jirovecii,a yeastlike fungus.Although most of us have been infected with this organism,our immune systems almost always prevent disease.Finding the disease in Nathan suggested a serious immune dysfunction.An immunological workup revealed mild neutropenia (lower than normal numbers of neutrophils) but normal numbers of T and B cells,normal levels of complement,and normal complement activity.However,Nathan's blood exhibited exceptionally high levels of IgM but very low IgG and IgA levels.The physician suspected a specific defect in Nathan's T cells. Based on his findings regarding antibody production,which defect do you think Nathan's doctor suspects is causing Nathan's immunodeficiency?


A) a mutation affecting CD40
B) a mutation affecting CD8
C) a mutation affecting MHCI
D) a mutation affecting IL10

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Antigen bound by the molecule shown would be recognized by ________ cells. Antigen bound by the molecule shown would be recognized by ________ cells.   A)  T<sub>C</sub> B)  THβ‚‚ C)  TH<sub>17</sub> D)  B


A) TC
B) THβ‚‚
C) TH17
D) B

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Why is it important for T cells to weakly recognize self MHC proteins while strong recognition is problematic?

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T cells must be able to weakly recognize...

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Which of the following cell types is considered a "nonprofessional" antigen-presenting cell?


A) fibroblast
B) macrophage
C) dendritic cell
D) B cell

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How do the structure and function of the F(ab)and Fc regions of an antibody differ?

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The F(ab)region,made of both light and h...

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The immunoglobulin superfamily of proteins includes


A) immunoglobulins only.
B) immunoglobulins, major histocompatibility complex, and B- and T-cell receptors.
C) major histocompatibility complex and B- and T-cell receptors only.
D) IgA, IgG, IgM, IgE, and IgD only.

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Which of the following would you expect to elicit the largest production of antibodies?


A) haptens floating freely within plasma
B) a complex protein with many different epitopes
C) a polysaccharide with several identical segments
D) a small lipid

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B

Small molecules that do not elicit an immune response unless they are attached to immunogens are referred to as ________.

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