Adaptive Immune System and Humoral Response

Introduction

• Analogous to strategies in games: Know your enemy to defeat them.
• Immune system consists of innate and adaptive systems.
• Innate system: First responders, zero-tolerance policy.
• Adaptive system: Requires introduction to pathogens, slower initiation.

Adaptive Immune System

• Not present at birth, develops over time.
• Remembers pathogens once introduced.
• Systemic: Fights infections throughout the body.
• Two main components:
  • Humoral Immunity
  • Cellular Defenses

Humoral Immunity

• Relies on antibodies produced by B lymphocytes.
• Patrols body fluids, combats viruses/bacteria.
• Key to long-term immunity (e.g., mumps, ebola survival).
• Works by identifying antigens (foreign invaders or abnormal cells).

B Lymphocytes

• Origin and maturation in bone marrow.
• Develop immunocompetence and self-tolerance.
• Possess unique antibodies (2 billion possibilities) for antigens.
• Roam in lymph nodes, spleen, blood, and lymph.
• Activation upon encountering matching antigens, leads to:
  • Cloning
  • Army of effector cells
  • Memory cells

Antibody Actions

• Neutralization: Block binding sites on pathogens.
• Agglutination: Clump pathogens for easier macrophage action.
• Call for phagocytes and lymphocytes to destroy antigen-antibody complexes.

Immunity Types

• Active Humoral Immunity: Encounter with pathogens naturally or via vaccines.
• Vaccinations: Introduce weakened pathogens to prime immune response.
  • Lifelong immunity for stable antigens; yearly updates for evolving ones.
• Passive Humoral Immunity: Temporary immunity from:
  • Maternal antibodies (placenta, breast milk).
  • Exogenous antibodies (e.g., ebola treatment).

Conclusion

• Adaptive immune system's humoral response defends against extracellular pathogens.
• Key roles of B cells and antibodies.
• Upcoming focus on cellular defenses and intracellular pathogens.

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Credits

• Thank you to all contributors and supporters: Linnea Boyev, Kathleen Yale, Blake de Pastino, Dr. Brandon Jackson, Nicholas Jenkins, Nicole Sweeney, Michael Aranda, Thought Cafe.
• Support through Patreon: patreon.com/crashcourse