11.1 Antibody production and vaccination Flashcards
Simplified diagram showing some components of the immune system
What does the surface of our cells contain?
Large carbohydrates, glycoproteins and other polypeptides that can be recognised by our own immune system as self.
What organisms/non-organisms can have antigens on their surface?
Foreign cells such as bacteria, viruses, parasites, cancer cells and other pathogens also have an array of molecules on their surfaces that can potentially act as antigens.
What is an antigen?
Any molecule that can trigger an immune response, leading to the generation of antibodies.
How does the immune system respond to antigens?
The immune system can recognise antigens as ‘non-self’ and mount an immune response against them.
Every organism has ___ on the surface of its cells.
Unique molecules
The unique molecules that each organism has on the surface of its cells help ___
The immune system to recognise the cells as self.
Diagram of the SARS virus, showing glycoproteins, which act as antigens
Diagram showing some of the substances, cells, or entities that can be recognized as non-self/ possible origin of antigens
What is the basis for the ABO blood group system?
The presence of cell-surface antigens.
What do all red blood cells have on their surface regardless of blood type?
Antigen H
Antigen H does not ___
Trigger an immune response.
How are blood groups produced?
- Different molecules can be added to antigen H to produce blood groups A and B.
- For blood group A, N-acetylgalactosamine is added, for blood group B, galactose is added. Blood group AB has both modified antigens.
Against which antigens on the surface of red blood cells does the immune system form antibodies and why?
- The immune system forms antibodies against whichever ABO blood group antigens are not found on the individual’s RBCs.
- Thus, a group A individual will have anti-B antibodies and a group B individual will have anti-A antibodies.
- If a foreign antigen is introduced, for example, if an individual with blood type A receives blood type B during a transfusion, anti-B antibodies will be produced and agglutination will occur.
What is agglutination?
The clumping of a liquid, in this case, blood.
What is hemolysis?
The rupture of the red blood cell’s membrane, leading to the release of the hemoglobin and other internal components into the surrounding fluid.
What will agglutination lead to?
Hemolysis (‘rupturing’ of blood cells) and may result in the death of the patient.
Diagram showing all the possible combinations between donors of blood (top row) and recipients (left column), as well as the resulting reaction.
It also shows that somebody who is blood group O is a universal donor.
Diagram of agglutination in the blood
The transfusion of type A blood to a person who has type O blood would result in ___
The recipient’s anti-A antibodies clumping the donated red blood cells.
What happens once a pathogen or another antigen enters the body and why?
- It triggers a response.
- The body needs to make sure that the infection will be contained as quickly as possible, as well ensuring that it can recognize and deal with such an infection if it recurs.
Diagram showing an overview of the immune response
.
Steps of the immune response
- The antigen is quickly ingested (via phagocytosis) by macrophages and B cells.
- Both process the antigen and present it on their surface.
- The macrophage (now called an antigen-presenting cell) interacts with a helper T cell.
- This activates the helper T cell.
- The activated helper T cell interacts with the B cell that has the antigen on its surface (shown in step 2 in the diagram) and activates it.
- The activated B cell rapidly divides by mitosis to form clones of plasma cells and memory cells.
- The plasma cells possess lots of rough endoplasmic reticulum and a well-developed Golgi apparatus making them well-suited for producing antibodies (of one specific type) against the antigen.
Why are antibodies and memory cells important in the body?
- The antibodies help to destroy the antigen.
- To be immune against a certain infectious pathogen, the body needs antibodies that are already in your blood, or to have memory cells that produce a specific antibody against this type of infective agent.
- Vaccination can achieve both of these results.
Binding of B cells
- Only the B cells with receptors (antibodies) that can bind the antigen will take in the antigen for processing.
- This ensures that only the B cells that can produce the specific antibodies against the antigen are selected for cloning in later stages.
The receptors on B cells bind to ___
Antigens
Cells activated by antigen exposure lead to the production of ___
-Plasma cells that secrete antibodies for the antigen.
-Once activated by exposure to the antigen and the interaction with the activated helper T cell, some B cells turn into plasma cells that start producing vast quantities of antibodies.
What happens once the immune system has reacted to the invasion of an antigen?
Antibodies (proteins that bind to foreign substances) are produced.
Diagram of an antibody
Describe the structure of an antibody
- An antibody has constant and variable regions.
- The variable region is the part of the antibody which is highly specific to a particular antigen.
- The long and short chains are held together by disulfide bonds.
What are antibodies used for once they are produced?
They are used in a number of ways to aid the destruction of pathogens.
Diagram showing the various functions of antibodies
What is the difference between antibodies and antigens?
- Antibodies are proteins produced by plasma cells (a B cell originally) in response to an antigenic reaction.
- Antigens are any entities that trigger an immune response. This could be a protein, virus, bacterium, parasite, fungus, or large glycoprotein.
Outline four modes of antibody action
- Agglutination – Antibodies cause the sticking together of pathogens by attaching to the antigens on the surface. These clumped masses of pathogens are then easily ingested and destroyed by phagocytes. The large agglutinated mass can be filtered by the lymphatic system and then phagocytized.
- Opsonization – Antibodies make pathogens recognizable by binding to them and linking them to phagocytes.
- Neutralization of toxins – Antibodies bind to toxins produced by pathogens in the blood plasma, preventing them from affecting susceptible cells.
- Neutralisation of viruses and bacteria – Antibodies can bind to the surface of viruses, preventing them from entering host cells.
- Complement activation – The complement system is a collection of proteins that ultimately leads to the perforation of the membranes of pathogens. Antibodies bound to the surface of a pathogen activate a complement cascade, which leads to the formation of a “membrane attack complex” that forms a pore in the membrane of the pathogen allowing water and ions to enter the cell, causing the cell to lyse.
Diagram showing antibody actions
Why is the chance that some childhood diseases, such as measles or chickenpox, would affect you later in life minimal?
Once exposed to an antigen, for example the virus that caused measles, your body produces antibodies and memory cells.
What is a primary response?
The immune response triggered on the first encounter of the body with an antigen.