Overview
This lecture explains passive immunization, which provides immediate but short-term protection by transferring antibodies from another source, covering its types, history, modern uses, advantages, disadvantages, and future trends.
Passive Immunization Basics
- Passive immunization means giving a person someone else’s antibodies to protect or treat against infectious diseases.
- Unlike active immunity, passive immunity is short-lived, lasting only a few weeks or months.
- Passive immunization provides immediate protection, while active immunity (from infection or vaccination) develops over time.
Types of Passive Immunity
- Natural Passive Immunity: Infants receive antibodies from their mothers through the placenta, colostrum, and breast milk, offering short-term protection.
- Artificial Passive Immunity: Antibodies are given as medication, derived from immune humans or animals, to provide temporary immunity.
Historical Development
- Passive immunization was first used in the late 19th century, beginning with diphtheria antitoxin from animals.
- Early successes led to treatments for tetanus, smallpox, bubonic plague, and prevention studies for hepatitis A and measles.
- Gamma globulin was tested for polio prevention but replaced by the polio vaccine due to limitations.
Modern Uses of Passive Immunization
- Used to treat diseases like diphtheria and cytomegalovirus or as post-exposure prevention (e.g., rabies, measles, hepatitis, tetanus).
- Especially useful for high-risk individuals or those with immune deficiencies.
- Sometimes combined with vaccines, such as in post-rabies exposure.
Advantages and Disadvantages
- Advantages: Provides rapid protection within hours or days and can help those with weak immune systems.
- Disadvantages: Short duration of protection, high production cost, risk of allergic reactions (especially from animal-derived antibodies), and need for intravenous administration.
Future Trends
- Monoclonal Antibodies (MAbs): Laboratory-produced, highly specific antibodies with applications in infectious and noninfectious diseases.
- Only one MAb is currently licensed for preventing RSV in high-risk infants.
- Research is ongoing into new production methods and emergency uses (e.g., for bioterror threats).
Key Terms & Definitions
- Passive Immunization — Transfer of ready-made antibodies to provide immediate, short-term protection.
- Active Immunity — Immunity generated by the body’s own response to infection or vaccination.
- Antibody — A protein produced by the immune system to recognize and neutralize pathogens.
- Colostrum — The first milk produced after childbirth, rich in antibodies.
- Monoclonal Antibody (MAb) — Laboratory-made antibodies targeting a specific antigen.
Action Items / Next Steps
- Review the differences between active and passive immunity.
- Learn examples of diseases treated or prevented by passive immunization.
- Understand the significance of monoclonal antibodies in modern medicine.