Clonal Selection

Definition

Clonal selection is the process by which specific immune cells are activated and proliferate in response to a particular antigen, leading to the generation of a clone of identical cells that can effectively target that antigen. This mechanism is central to the adaptive immune response, ensuring that the body can mount a tailored defense against specific viruses or pathogens it encounters.

5 Must Know Facts For Your Next Test

1. Clonal selection allows for a rapid and efficient immune response by enabling the proliferation of specific immune cells that recognize and respond to a particular pathogen.
2. During an infection, only those B and T cells with receptors that specifically bind to the viral antigens are activated and begin to divide.
3. The process results in both effector cells, which actively fight the infection, and memory cells, which provide long-term immunity against future infections by the same virus.
4. Clonal selection is crucial for generating diversity in the immune response, as it produces a wide array of antibodies and T cell receptors capable of recognizing various pathogens.
5. The effectiveness of clonal selection can be influenced by factors such as the type of antigen present and the overall health and condition of the immune system.

Review Questions

• How does clonal selection contribute to the specificity of the adaptive immune response?
  • Clonal selection ensures that only those immune cells that specifically recognize an invading pathogen are activated. When a virus enters the body, B and T cells with receptors that match the viral antigens will bind to them. This binding triggers their activation and subsequent proliferation, resulting in a large number of identical cells that can effectively target and eliminate the virus. Thus, clonal selection allows for a highly specific immune response tailored to the exact nature of the pathogen.
• Discuss the role of memory cells generated through clonal selection in future infections by the same virus.
  • Memory cells generated through clonal selection play a pivotal role in providing long-term immunity against previously encountered pathogens. After an initial infection, some B and T cells differentiate into memory cells instead of effector cells. These memory cells remain in the body for years, sometimes even decades, and can rapidly respond if the same virus invades again. This leads to a quicker and more robust immune response upon re-exposure, often preventing reinfection or reducing its severity.
• Evaluate how defects in clonal selection can lead to immunological disorders or ineffective responses to viral infections.
  • Defects in clonal selection can have serious consequences for the immune system's ability to respond effectively to viral infections. For instance, if there is a failure in selecting or activating B or T cells that recognize specific viral antigens, it could result in inadequate antibody production or insufficient cytotoxic activity against infected cells. This dysfunction can lead to chronic infections, as seen in conditions like HIV/AIDS where clonal selection is impaired. Additionally, inappropriate clonal selection can contribute to autoimmune diseases where the immune system mistakenly targets self-antigens, leading to tissue damage.

Related terms

Antigen: A substance that triggers an immune response, often a protein or polysaccharide found on the surface of pathogens like viruses.

B Cells: A type of white blood cell that plays a crucial role in the adaptive immune response by producing antibodies specific to antigens.

T Cells: Another type of white blood cell involved in the adaptive immune response, which helps in directly killing infected cells or coordinating the immune response.