promote inflammation, slow the spread of infection, and help activate an adaptive
immune response in peripheral lymphoid organs.
23. Why does it take approximately a week after infection for the benefits of an adaptive
immune response to start to be felt?
Prior to the establishment of an effector population of lymphocytes, several events
(1) specific recognition of pathogen by lymphocyte receptors (clonal selection);
(2) proliferation of pathogen-specific lymphocytes to expand responding
populations (clonal expansion); and
(3) differentiation into effector lymphocytes with the resulting establishment of an
organized adaptive immune response.
24. What is meant by the term “immunodeficiency disease”?
Immunodeficiency diseases are disorders in which some aspect of host immune
defense is missing or defective.
25. Why would an individual’s ability to combat infection be compromised by an
Susceptibility to infection increases when either innate or acquired immune
responses are not operating correctly. This may cause susceptibility to particular
subsets of pathogens, or to all pathogens depending on the particular deficiency.
26. What causes an immunodeficiency disease?
Immunodeficiency diseases may be caused by autosomal or sex-linked mutations
affecting genes involved in innate or acquired immune responses. Alternatively,
immunodeficiency diseases may arise through infection with pathogens that
suppress or disrupt an otherwise healthy immune system.
27. Vaccination is best described as prevention of severe disease by:
a) deliberate introduction of a virulent strain of an infectious agent
b) prior exposure to an infectious agent in an attenuated or weakened form
c) prophylactic treatment with antibiotics
d) stimulating effective innate immune responses
e) using effective public health isolation regimens such as quarantine
28. Which of the following explains why immunity to influenza may appear to be
a) Effective immunological memory fails to develop.
b) Immune responses to influenza involve innate immune mechanisms only.
c) The primary and secondary immune responses are equivalent.
d) Influenza virus targets memory cells.
e) New influenza variants able to escape prior immunity regularly.