BRAINCAKEClonal Selection
The body contains millions of different lymphocytes, each with receptors complementary to a different antigen, but only a very few of them match any one antigen. Clonal selection is the process by which an antigen 'selects' the lymphocytes with complementary receptors, which then multiply.
1. Selection. When a pathogen enters the body, its antigens bind only to the B cells and T cells whose receptors have a complementary shape. All the other lymphocytes are unaffected.
2. Clonal expansion. The selected lymphocytes are activated (B cells need cytokines from T helper cells) and divide repeatedly by mitosis. Because mitosis produces genetically identical cells, each selected lymphocyte gives rise to a clone of cells with exactly the same receptors.
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More in Response to Infection
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