The cellular response: role of antigen-presenting cells; role of helper T cells (TH) in stimulating cytotoxic T cells (TC), B cells and phagocytes
When a pathogen invades, specialised white blood cells called helper T cells act as coordinators. They receive a signal from antigen-presenting cells and then activate the immune system's other defenders.
Real World
HIV destroys helper T cells, collapsing the entire coordinated immune response — this is why AIDS patients become vulnerable to opportunistic infections that healthy immune systems would normally suppress effortlessly.
Exam Focus
Use precise terminology: 'antigen-presenting cell displays antigen on MHC protein' scores more than 'cell shows the antigen to T cells'.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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