OVERVIEW OF THE IMMUNE SYSTEM
ONTOGENY AND PHYSIOLOGY OF IMMUNE SYSTEM
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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when an antigen is displayed by a dendritic cell.
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when a cytotoxic T cell releases cytokines.
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when natural killer (NK) cells come in contact with a tumor cell.
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) in the bone marrow during the self-tolerance test.
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Detailed explanation-1: -The dendritic cells then migrate to a peripheral lymphoid organ and activate naïve helper T cells to differentiate into either TH1 or TH2 effector cells, depending on the cytokines the dendritic cells produce.
Detailed explanation-2: -After binding to the antigen and MHC class II molecule presented by the dendritic cell, the naïve helper T cell becomes activated and proliferates. Instead of gaining the ability to kill infected cells, helper T cells acquire the ability to activate cells that bear MHC class II molecules.
Detailed explanation-3: -Mature DCs are characterized by the production of cytokines, such as IL-12, and by the expression of homing receptors, such as CCR7, which directs the migration of DCs into the T-cell regions of secondary lymphoid organs. Together these changes enable DCs to effectively activate naïve T cells.
Detailed explanation-4: -The CD4 receptor interacts with major histocompatibility complex (MHC) class II molecules. MHC class II molecules sense when there’s an infection or foreign substance in your body. The CD4 receptor and MHC class II molecules activate the helper T-cells.
Detailed explanation-5: -Immune responses are initiated in the T-cell areas of secondary lymphoid organs where naïve T lymphocytes encounter dendritic cells (DCs) that present antigens taken up in peripheral tissues.