THE CONTEXT
The passage explains idiotype-mediated regulation and the genetic basis of antibody diversity, followed by key features of immune responses and antibody-producing cells.
Idiotypes and network regulation
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Idiotypes are distinct amino acid sequences at the antigen-combining site and adjacent parts of the antibody variable region.
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An idiotype can act as an antigenic determinant and induce anti-idiotypic antibodies. These antibodies can themselves induce further antibodies.
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The resulting idiotype network is postulated to regulate the amount of antibodies produced and the number of antibody-forming cells in action.
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The variable region carrying the antigen-combining site differs between antibodies.
Genetic basis of antibody diversity
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An individual is estimated to have the capacity to produce 10⁸ different antibody molecules.
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Encoding every antibody molecule with a separate gene would require millions of genes dedicated to antibody production.
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The discovery of split genes for immunoglobulins challenged the one-gene–one-protein dogma and had implications beyond immunology.
Primary and secondary immune responses
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The primary immune response follows the first encounter with a microorganism or antigen. Its latent period is usually long, and the response may be transient and mild.
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The secondary immune response follows a second or subsequent encounter with the same antigen. It has a shorter latent period and is more vigorous and prolonged.
Lymphocytes and antibody terminology
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B lymphocytes and T lymphocytes are the two principal lymphocyte types involved in the specific immune response.
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B lymphocytes are precursors of antibody-producing plasma cells.
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Immune responses may be humoral, meaning antibody-mediated, or cellular, meaning cell-mediated.
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Monoclonal antibodies are produced by a single clone and directed against a single antigenic determinant.