USMLE

Antibodies

816 views
Immunology
  1. Innate Immunity
  2. Adaptive Immunity
  3. Macrophages
  4. Neutrophils
  5. Dendritic Cells
  6. Mast Cells
  7. Eosinophils
  8. Basophils
  9. Natural Killer Cells
  10. Antigens
  11. MHC I and II
  12. Antibodies
  13. B Lymphocytes Overview
  14. B Cell Stages
  15. B-Cell Activation
  16. Plasma B-Cells
  17. Memory B-Cells
  18. T-Lymphocytes Overview
  19. T-Cell Stages
  20. Types of Activated T-Cells

Summary

Antibodies are Y-shaped proteins produced by B-cells of the adaptive immune system. As a key player in our immune system’s humoral response, antibodies recognize and bind to antigens either as freely circulating proteins or as membrane-bound proteins. The antibody is made up of 2 light chains and 2 heavy chains, which come together to form variable regions on one end and a constant region on the other. The variable region is responsible for binding a wide variety of antigens, while the constant region works to alert other parts of our immune system to destroy whatever is bound by the antibody.

Key Points

  • Antibodies (Immunoglobulins)
    • Main component of the humoral response of the adaptive immune system
    • Y-shaped proteins
    • Recognize and bind antigens
      • Binding to antigens attracts innate immune cells to phagocytose and destroy the pathogen
    • Produced by B cells
      • Each B cell makes a single type of antibody or immunoglobulin, which can recognize and bind to a specific antigen 
      • Can exist as membrane-bound cell receptors or independently in circulation 
    • Structure of an antibody
      • Two identical heavy chains and light chains
        • Connected by disulfide bonds
      • Both heavy and light chain involved in forming:
        • Constant region
          • Does not bind antigens
          • Signals to other cells (eg, phagocytes) and proteins to destroy antigen bound at other end
        • Variable region
          • Binds antigen
          • Unique amino acid structure of this region determines specificity of antibody