Chapter 02: Innate Immunity Test Bank MULTIPLE CHOICE 1. Which of the following statements about the innate immune system is NOT true? A. Innate immunity is present in all multicellular organisms, including plants and insects. B. Deficiencies in innate immunity markedly increase host susceptibility to infection, even in the setting of an intact adaptive immune response. C. Innate immunity is better suited for eliminating virulent, resistant microbes than is adaptive immunity. D. The innate immune response can be divided into recognition, activation, and effector phases. E. The innate immune response against microbes influences the type of adaptive immune response that develops. ANS: C Innate immunity is the first line of defense against infections, yet many pathogenic microbes have evolved strategies to resist innate immunity. Adaptive immunity, being more potent and specialized, plays a critical role in defending against these virulent microbes. Innate immunity is the phylogenetically oldest mechanNismURofSmIiNcrGobTiaBl.deCfeOnMse, and it is present in all multicellular organisms, including plants and insects. Studies have shown that hampering effector mechanisms of innate immunity renders hosts much more susceptible to infection, even with a functional adaptive immune system. It is also true that, like the adaptive response, the innate immune response consists of recognition, activation, and effector phases. Although it provides the initial, rapid response against microbes, innate immunity can influence adaptive immune responses to tailor them against particular microbes. 2. A 4-year-old girl stepped on a rusty nail in her backyard. Two days later, she is taken to the pediatrician because her heel is painful, red, and swollen and is warm to the touch. All of the following are mechanisms of innate immunity that may be protecting the patient against pathogenic microbes in the heel wound EXCEPT: A. Epithelial barrier function of the skin of her foot B. Intraepithelial lymphocytes present in the skin C. Circulating neutrophils migrating to the site of the wound D. Soluble cytokines that induce a local inflammatory response E. Circulating anti-tetanus toxin antibodies ANS: E Secreted antibodies against protein antigens are effectors of humoral immunity, a component of the adaptive immune system. All other mechanisms listed are part of the innate immune system. Intact epithelial surfaces prevent microbial entry, and epithelial cells express anti-microbial factors, such as defensins. Neutrophils are effector cells that function in early phagocytosis and killing of microbes. Cytokines that mediate inflammation (e.g., tumor necrosis factor,read more
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