Activated lymphocytes can generate immediate effector responses and form memory cells for subsequent antigen encounters.
B-cell memory
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A small proportion of activated B cells become long-living memory cells instead of plasma cells.
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These memory cells produce a secondary response on subsequent contact with the antigen.
Cytotoxic T-cell activation and action
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Cytotoxic T cells, designated CD8/TC cells, are activated by contact with antigen presented along with MHC Class I molecules.
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They also require IL-2 as a second signal, supplied by activated helper T cells.
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On contacting a target cell carrying the antigen on its surface, activated cytotoxic T cells release cytotoxins that destroy the target. Targets may be virus-infected cells or tumour cells.