PATHOLOGY MCQ
IMMUNE RESPONSE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Does not acquire immune memory after initial exposure to antigen
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Amplify inflammatory response after bacterial infection
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Possess CD16, CD56 and CD3 surface proteins
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Major early role in recognizing and killing virus-infected host cells and tumor cells
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Detailed explanation-1: -NK cells are innate immune lymphocytes that express a vast repertoire of germ-line encoded receptors for target recognition. These receptors include inhibitory and activating proteins, among the latter of which is CD16, a low affinity binding Fc receptor.
Detailed explanation-2: -CD56 is the archetypal phenotypic marker of natural killer cells but can actually be expressed by many more immune cells, including alpha beta T cells, gamma delta T cells, dendritic cells, and monocytes.
Detailed explanation-3: -NATURAL killer (NK) cells are large granular lymphocytes capable of killing tumour cells in a non-MHC restricted manner1, 2. NK cells do not express cell-surface CD3, or any known target recognition structure analogous to the T cell antigen receptor (TCR) heterodimers ( or )3–8.
Detailed explanation-4: -The CD56dim CD16bright NK cells represent at least 90% of all peripheral blood NK cells and are therefore the major circulating subset. A maximum of 10% are CD56bright NK cells. The various subsets can easily be distinguished by flow cytometry as depicted in Fig.