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B Lymphocytes

Biology: AQA A Level, topic 2.4.4

B Lymphocytes

B lymphocyte cells are white blood cells that are involved in the humoral immune response. The steps involved in this process are:

1) Activation of B cells

1) Activation of B cells

  • TH cells activates B cells.
  • Activation of the B cells causes the B cells to divide into identical cells called plasma cells.
  • The selection of the correct B cell with a complementary receptor to a pathogen's antigen is called clonal selection.
  • Once the correct B cell has been selected, it divides multiple times to produce many identical plasma cells. Plasma cells make antibodies against specific antigens. This process is called clonal expansion.
2) Detection of antigens

2) Detection of antigens

  • B cells have specific proteins called antibodies on their cell surface membranes.
  • Each antibody is complementary (specific) to a specific antigen.
  • When an antigen binds to an antibody, an antigen-antibody complex is formed.
  • Binding of antigens to B cells also causes clonal selection.
3) Plasma cells

3) Plasma cells

  • Clonal selection leads to clonal expansion, which is the production of many plasma cells that have the specific antibodies for the antigens present in the body.
  • The antibodies are called monoclonal antibodies.
  • Monoclonal antibodies bind to the antigens of the pathogens.
4) Agglutination

4) Agglutination

  • Agglutination 'clumps' the pathogens together.
  • The pathogens are engulfed by phagocytes via phagocytosis.
  • The pathogens are destroyed.

Test yourself on B Lymphocytes

  • Steps Involved in the Humoral Response

  • Which of the following statements about B lymphocytes are true?

  • What is the name of the process where B cells divide into identical cells that produce antibodies?

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