Interaksi Antigen Antibodi S1Farmasi UMMAT

Summary

This lecture explains the interaction between antigens and antibodies, highlighting their role in immune responses. Antigens, substances that trigger immune reactions, bind with antibodies, which are proteins that help eliminate harmful antigens. The discussion covers key concepts like antibody affinity and avidity, the differences between monoclonal and polyclonal antibodies, and the processes of precipitation, agglutination, neutralization, and complement activation. These interactions are applied in diagnostic methods, such as pregnancy tests and immunotherapy. The session emphasizes the importance of antigen-antibody interactions in both health and disease management.

Takeaways

• 😀 Antigens are substances that trigger an immune response, while antibodies are proteins that are part of this response.
• 😀 The interaction between antigens and antibodies helps eliminate harmful antigens from the body.
• 😀 Affinity refers to the strength of the bond between one antibody and the epitope of an antigen, while avidity refers to the overall strength of the interaction between the antibody and antigen.
• 😀 Avidity is higher when the antigen is polyvalent, meaning it has multiple epitopes that antibodies can bind to.
• 😀 Precipitation occurs when soluble antigens bind to antibodies to form a precipitate, aiding in phagocytosis.
• 😀 Agglutination occurs when insoluble antigens bind to antibodies, often in the form of small particles, and helps facilitate phagocytosis.
• 😀 Neutralization is when antibodies block the active sites of pathogens or toxins to prevent them from entering cells and causing damage.
• 😀 Complement activation occurs when antigen-antibody interactions trigger the immune system's complement proteins, leading to inflammation and phagocytosis.
• 😀 Various diagnostic methods, such as immunodiffusion, immunohistochemistry, ELISA, and immunoblotting, utilize antigen-antibody interactions.
• 😀 Pregnancy tests use antigen-antibody interactions, where antibodies react with HCG in urine to confirm pregnancy.

Q & A

What is the role of antigens in the immune system?

Antigens are substances that trigger an immune response in the body. They are recognized by the immune system as foreign or harmful, prompting the production of antibodies to neutralize or eliminate them.

What are antibodies, and how do they function in the immune response?

Antibodies, also known as immunoglobulins, are proteins produced by the immune system in response to the presence of antigens. They recognize and bind to specific epitopes (parts of antigens), aiding in the elimination of pathogens or harmful substances.

What is the difference between affinity and avidity in the interaction between antigens and antibodies?

Affinity refers to the strength of the binding between a single antibody and an antigen's epitope, whereas avidity refers to the overall binding strength between multiple antibody-antigen interactions, especially when the antigen has multiple epitopes.

How does the valency of an antigen affect its avidity in antibody interactions?

The valency of an antigen, which refers to the number of epitopes it has, impacts its avidity. A monovalent antigen (with one epitope) will have lower avidity, while a multivalent antigen (with multiple epitopes) leads to higher avidity due to more binding sites for antibodies.

What is the significance of glomerulonephritis in the context of antigen-antibody interactions?

Glomerulonephritis can occur as a result of antigen-antibody interactions, particularly in cases of infections like streptococcus, where immune complexes form and deposit in the kidneys, leading to inflammation and damage.

What is the principle behind precipitation in antigen-antibody reactions?

Precipitation occurs when soluble antigens and antibodies form immune complexes that precipitate out of solution. This process helps in the removal of antigens from the body by enhancing phagocytosis.

What is agglutination, and how does it contribute to immune defense?

Agglutination is the clumping of insoluble antigens (such as particles or cells) when they interact with antibodies. This process aids in the clearance of pathogens by making them easier for immune cells to engulf and eliminate.

How does neutralization work in the context of antibody-antigen interactions?

Neutralization occurs when antibodies bind to harmful agents like toxins or pathogens, preventing them from entering or damaging host cells. This process is crucial in protecting cells from toxic effects or viral infections.

What are the three pathways of complement activation in immune defense?

The three complement activation pathways are the classical pathway (triggered by antigen-antibody complexes), the alternative pathway (triggered by pathogen surface molecules), and the lectin pathway (triggered by mannose on pathogen surfaces). Each pathway leads to the activation of the complement system, which aids in immune responses like inflammation and pathogen elimination.

How are antigen-antibody interactions utilized in medical diagnostics?

Antigen-antibody interactions are used in diagnostic methods such as immunodiffusion, immunohistochemistry, ELISA, and immunoblotting. These techniques detect the presence of specific antigens or antibodies in samples, aiding in the diagnosis of diseases like infections or cancer.