Edexcel A (SNAB) A Level Biology:复习笔记6.2.6 B Cell Response

• B cells, also known as B lymphocytes, are a second type of white blood cell in the specific immune response
  • B cells remain in the bone marrow as they mature, hence the B in their name
• B cells have many specific receptors on their cell surface membrane
  • The receptors are in fact antibodies, and are known as antibody receptors
  • Each B cell has a different type of antibody receptor, meaning that each B cell can bind to a different type of antigen

Mature B cells each have different types of antibody receptors on their cell surface membrane

• If the corresponding antigen enters the body, B cells with the correct cell surface antibodies will be able to recognise it and bind to it
  • When the B cell binds to an antigen it forms an antigen-antibody complex
• The binding of the B cell to its specific antigen, along with the cell signalling molecules produced by T helper cells, activates the B cell
• Once activated the B cells divide repeatedly by mitosis, producing many clones of the original activated B cell
• The daughter cells differentiate into two main types of cells
  • Effector cells, which go on to form plasma cells
    • Plasma cells produce specific antibodies to combat non-self antigens
  • Memory cells
    • Remain in the blood to allow a faster immune response to the same pathogen in the future

During a primary immune response B cells divide by mitosis to form plasma cells and memory cells. Note that a primary response occurs the first time an individual comes into contact with a particular pathogen