Lecture Notes: Adaptive Immune System and Humoral Response

Key Concepts

• Adaptive Immune System

  • Unlike the innate immune system, the adaptive immune system requires introduction to a specific pathogen.
  • It is slower to develop as it needs to recognize and remember pathogens.
  • Vaccination is a method of preemptively introducing pathogens to the immune system.

• Memory

  • Once introduced to a pathogen, the adaptive immune system remembers it permanently.
  • Allows for systemic response across the whole body, not localized.

Components of Adaptive Immunity

• Humoral Immunity

  • Involves the production of antibodies by B lymphocytes (B cells).
  • Antibodies are proteins that patrol bodily fluids like blood and lymph.
  • B cells originate and mature in the bone marrow.
  • Each B cell has unique antibodies that recognize specific antigens.

• Antigens

  • Foreign molecules that trigger an immune response.
  • Can be bacteria, viruses, fungi, toxins, or diseased cells.

B Lymphocytes (B Cells)

• Maturation

  • Develop the capability to distinguish between self and non-self antigens.
  • Display thousands of unique protein receptors (antibodies).

• Activation

  • B cells are activated when they bind to a matching antigen.
  • They replicate rapidly to create an army of effector and memory cells.

• Effector Cells

  • Also known as plasma cells; they produce antibodies at a high rate.
  • Antibodies neutralize antigens and mark them for destruction.
  • Two primary methods include neutralization and agglutination.

• Memory Cells

  • Long-lived cells that help mount a quick secondary response if the antigen reappears.

Active vs Passive Immunity

• Active Humoral Immunity

  • Results from direct exposure to pathogens or through vaccination.
  • Vaccinations use dead or weakened pathogens to elicit an immune response.

• Passive Humoral Immunity

  • Temporary immunity gained from external antibodies.
  • Can be natural (from mother to child) or artificial (through donated plasma).

Conclusion

• Importance of Vaccination

  • Essential in combating serious diseases and providing long-lasting protection.
  • Particularly effective for diseases with stable antigens.

• Next Steps

  • Future discussions will cover cellular immunity, which involves direct cell-to-cell combat against pathogens inside host cells.