The B Lymphocyte Response (OCR A Level Biology)

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Specific Immune Response: B Lymphocytes

Maturation of B-lymphocytes

  • B-lymphocytes (B cells) remain in the bone marrow until they are mature and then spread through the body, concentrating in lymph nodes and the spleen
  • During the process of maturation B cells gain specific cell surface receptors called B cell receptors (BCRs)
    • The receptors on the cell surface of B cells are antibodies and are sometimes referred to as antibody receptors
    • Part of each antibody molecule forms a glycoprotein receptor that can combine specifically with one type of antigen
    • A small number of B cells have the same BCRs, these genetically identical cells are called a clone

The maturation of B lymphocytes, downloadable AS & A Level Biology revision notes

Mature B cells have many different types of antibody receptor on their cell surface membranes

B cells in the immune response

  • In order to play their role in the immune response B cells need to be activated and increase in number; this occurs as follows:
  • Clonal selection and activation
    • B cells with complementary antibody receptors bind to antigens on antigen presenting cells; this is clonal selection
      • These antigen presenting cells can be phagocytes, infected cells, or the pathogens themselves
    • This binding, together with interleukins released by T helper cells activates the B cells
  • Clonal expansion
    • Activated B cells divide by mitosis to produce clones
    • This results in large numbers of identical B-lymphocytes being produced over a few weeks
    • Some of these B-lymphocytes differentiate into plasma cells
      • Plasma cells secrete lots of antibody molecules (specific to the antigen) into the blood, lymph or linings of the lungs and the gut
    • The other B-lymphocytes become memory cells that remain circulating in the blood for a long time

The function of B-lymphocytes during a primary immune response_1, downloadable AS & A Level Biology revision notes

Activated B cells differentiate into plasma cells and memory cells

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Lára

Author: Lára

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.