Lecture 3 - Recognition of antigen by B-cells and antibody Flashcards
What is the main role of B-cells?
To attack invaders outside the cells
What is the main role of T-cells?
To attack invaders inside the cells
True or False? C and T cells have receptors on their surface that can recognise foreign molecules.
True
Name the ways that Antibodies can be expressed. [2]
- B-cell surface
- Secreted from B-cells
What are the main functions of Antibodies? [2]
- Bind to foreign antigens
- Mediate effector functions to eliminate/neutralise foreign invaders
What are the components of an Antibody? [2]
- Fragment antigen binding (Fab) fragment
- Fragment crystallisable (Fc) fragment
What is an Antigen?
Part of a molecule that can be recognised by an antibody.
List a few examples of Antigens. [4]
- Proteins
- Carbohydrates
- Lipids
- DNA
What are antigen epitopes?
Part of the antigen that are recognised by antibodies
True or False. Antigen and Antibody binding is not specific.
False.
What is a conformational epitope?
- Formed by protein folding
- May not be a continuous sequence of amino acids
What is a linear epitope?
Formed by a continuous sequence of amino acids
True or False. The antigen binding site must be complementary to the hypervariable regions of an antibody.
True
What are the forces that are involved in antibody binding? [4]
- Hydrogen bonds
- Electrostatic interactions
- Van der Waals forces
- Hydrophobic interactions
What is affinity, relating to antibody binding?
The stronger the binding between the antibody and antigen mean a higher affinity
What is avidity?
- When an antibody used both binding sites to bind to 2 epitopes.
- This increases the avidity (binding strength)
When are antibodies made?
After an infection has occured
What effect do antibodies have on the body? [5]
- Neutralisation of pathogens
- Opsonisation of pathogens
- Complement activation
- Agglutination of pathogens
- Antibody dependent cell mediated cytotoxicity (ADCC)
What happens when antibodies neutralise a pathogen?
The antibodies prevent the pathogen from binding to its target
What happens during opsonisation of a pathogen?
The pathogen gets tagged by antibodies and is phagocytosed
What happens during complement activation by antibodies?
Antibodies attached to the surface of the pathogen activate the complement system
What happens during antibody dependent cytotoxicity (ADCC)?
- Cells (NK cell or macrophages) with FcR bind to antibodies
- Mediated extracellular killing
What are applications for immunotherapy?
Use the immune system to attack tumours
What is different between each antibody class?
The Fc region
