11.2 ACTIONS OF ANTIBODIES

• What are the five main mechanisms that antibodies use to remove foreign antigens?


  Agglutination, neutralization, opsonization, precipitation, and lysis
• What is the process of agglutination in the context of antibodies?


  • Antibodies bind to surface antigens
  • A clump is formed
  • The larger molecule becomes a target for macrophages to phagocytose
• What happens when incompatible blood types are mixed?


  It can lead to fatal consequences due to agglutination
• How do antibodies neutralize toxins produced by bacteria?


  • Antibodies bind to the toxins
  • They render the toxins ineffective
  • Neutralizing antibodies block pathogen entry
• What is opsonization and its role in immunity?


  • Antigens are marked by binding antibodies
  • The marker facilitates phagocytosis
  • Antibodies like IgG and IgE act as opsonins
• What occurs during the precipitation process involving antibodies?


  • Antibodies bind to soluble antigens
  • An insoluble product is formed
  • The product can be easily removed by phagocytes
• How do antibodies cause lysis of bacteria?


  • Antibodies bind to bacterial antigens
  • They activate the complement system
  • Pores are formed in the bacterial cell wall, leading to lysis
• What is the role of the complement system in the lysis of bacteria?


  It forms pores in the bacterial cell wall
• Why are pathogens like bacteria targeted by antibodies?


  They have cell walls that can be easily targeted
• What is the significance of precipitation reactions in medical tests?


  • Used to determine the presence of pathogens
  • Commonly seen in tests/assays
  • Helps in diagnosing infections in patients' serums
• What is the main function of macrophages in the immune response?


  To phagocytose larger molecules formed by agglutination
• How does the action of neutralizing antibodies differ from that of opsonizing antibodies?


  Neutralizing antibodies block toxins, while opsonizing antibodies mark antigens for phagocytosis
• If a patient receives the wrong blood type, what mechanism of antibodies is primarily involved?

  Agglutination
• What is the outcome of the lysis process activated by antibodies?

  The bacterial cell wall breaks down, leading to cell death