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Question
Briefly explain the role of the following in providing defence against infection in the human body:
T-cells
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Solution
T-cells are generated in the thymus and are programmed to be specific for one particular foreign particle (antigen). Once they leave the thymus, they circulate throughout the body until they recognize their antigen on the surface of antigen-presenting cells (APCs). The T-cell receptor (TCR) on both helper T-cells and cytotoxic T-cells binds to the antigen as it is held in a structure called the MHC complex, on the surface of the APC. This triggers the initial activation of the T-cells. T-cells themselves do not secret antibodies but help B cells to produce them.
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