Immune System 4th Edition By Parham – Test Bank
11–11 Imagine a situation in which an individual who has a latent cytomegalovirus (CMV) infection receives a hematopoietic stem-cell transplant. Which of the following is likely to occur?
a. The memory T cells present at the time of transplantation would inhibit activation of newly generated naive T cells.
b. The CMV viral load would increase exponentially, overcoming the host and causing death.
c. The transplant-derived naive T cells would be activated and give rise to memory T cells that would persist and control viral load.
d. There would be a rapid increase in CMV viral load and expansion of T cells bearing CD45RA.
11–12 Which of the following are not a component of immunological memory?
a. effector B cells
b. memory T cells
c. memory B cells
d. long-lived plasma cells.
11–13 Identify three reasons why memory B cells respond more forcefully and effectively during secondary immune responses than naive B cells during primary immune responses.
11–14 The efficiency and specificity of adaptive immune defenses and immunological memory improve each time a particular pathogen is encountered because _____.
a. of protective immunity
b. effector memory T cells outnumber central memory T cells
c. the half-life of antibodies made in secondary and tertiary immune responses exceeds that of antibodies made in primary immune responses.
d. of affinity maturation.
11–15 Unlike naive lymphocytes, memory lymphocytes _____.
a. do not recirculate between the blood and secondary lymphoid organs
b. do not require the receipt of survival signals through their antigen receptors in order to persist
c. are immortal and continue to divide throughout the lifetime of an individual
d. secrete antibody continuously, although at a much lower rate than plasma cells
e. do not express CD27.
11–16 All of the following are ways in which plasma cells differ from memory cells except _____.
a. plasma cells lack surface immunoglobulin
b. cellular morphology
c. plasma cells are CD27-negative
d. plasma cells have undergone isotype switching
e. plasma cells are short-lived.
11–17 During a secondary immune response, high-affinity IgG antibodies are produced. Which of the following best explains why low-affinity IgM antibodies are not made?
a. Naive pathogen-specific B cells are suppressed by negative signaling through FcγRIIB1.
b. Naive pathogen-specific B cells isotype switch and hypermutate much more quickly during secondary immune responses.
c. Memory B cells outnumber naive B cells.
d. Low-affinity IgM antibodies are made only when antigen concentration is exceedingly high.
11–18 Which of the following molecules is not elevated on the surface of memory B cells compared with naive B cells?
a. MHC class II molecules
c. antigen receptor
e. co-stimulatory molecules.
11–19 Explain why memory B cells are more efficient at responding to pathogens than are naive B cells.
11–20 _____ accounts for the production of different isoforms of the CD45 protein observed in naive, effector, and memory T cells.
a. Isotype switching
b. Affinity maturation
c. Alternative splicing
d. Somatic hypermutation
e. Recirculation to peripheral tissues
(i) Memory B cells bearing pathogen-specific immunoglobulin are more numerous than naive B cells.
(ii) Memory B cells are activated more easily than naive B cells.
(iii) Memory B cells have already undergone isotype switching, somatic hypermutation, and affinity maturation.
11–19 During germinal-center reactions, isotype switching, somatic hypermutation, and affinity maturation generate memory B cells with higher-affinity receptors than those of naive B cells. This feature enables memory B cells to bind to pathogen antigens at very early stages of infection when the pathogen population is very small. Memory B cells also differentiate into plasma cells more rapidly than do naive B cells. These two characteristics allow antibody production to occur much sooner than would be the case with naive B cells. Cognate interactions with CD4 TFH cells are also more efficient owing to elevated MHC class II and co-stimulatory molecules on the surface of memory B cells compared with naive B cells.