Antigen persistence and the initiation of an immune response
THE CONTEXT
The passage describes prolonged persistence of pneumococcal polysaccharide and the cellular steps that initiate an immune response.
Antigen persistence
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Pneumococcal polysaccharide may persist in humans for up to 20 years after a single injection.
Participating cells and antigen presentation
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The immune response involves antigen-processing cells, T cells and B cells.
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Antigen-processing cells are principally macrophages and dendritic cells.
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The first step is capture and processing of antigen by antigen-processing cells, followed by presentation to T cells in association with an appropriate MHC molecule.