Humoral response Flashcards
What are B-lymphocytes?
A type of white blood cell that is involved in the humoral response
Where are B-lymphocytes made?
In the bone marrow
Where are B-lymphocytes matured?
In the bone marrow
What are the 4 cells involved in the humoral response?
- B cells
- Plasma cells
- Memory cells
- Helper T cells
What are B-cells?
Cells that have antibodies on their surface that bind to complementary antigens
What are plasma cells?
A type of B-cell that produces and secretes monoclonal antibodies against a specific antigen - they have a short lifespan of a few days
What are memory cells?
A type of B-cell that provide long-term immunity against specific pathogens by dividing into plasma cells if the body is re-infected - they have a much longer lifespan than plasma cells
Describe the process of the humoral response
1) Antigens in the blood collide with their complementary antibody on the surface of a B-cell
2) The antigen will enter the B-cell by endocytosis and then be presented on the B-cells surface
3) Helper T cells bind to these processed antigens which activates the B-cell to undergo mitosis to form plasma and memory cell clones
4) Cloned plasma cells produce and secrete the specific antibody which is complementary to the antigen on the surface of the pathogen, leading to the destruction of the pathogen
5) Memory cells will circulate the blood and tissue fluid, ready to divide rapidly into plasma cells if the body is infected by the same pathogen
What is the difference between clonal selection and clonal expansion?
Clonal selection - the B-cell with the correct antibody is selected for cloning by being activated by a helper T cell
Clonal expansion - The division of specific B-cells to produce genetically identical clones
What is the primary immune response?
- During the primary immune response, plasma cells and memory cells are created
- It takes time for the B cells to divide into plasma cells to produce the correct antibody so symptoms will be experienced
- Memory cells will be created to make the individual immune to this pathogen if re-infected
What is the secondary immune response?
- During the primary immune response, memory B cells are created
- When the body is re-infected with the same pathogen memory cells will divide rapidly into plasma cells and destroy the pathogen
- The response is very quick meaning the pathogen can be destroyed before symptoms develop
Compare the primary and secondary immune response
- Primary response is when pathogen is first encountered, secondary is the second or subsequent encounter
- Primary response is slow, the secondary response is faster
- Symptoms are experienced in the primary response, no symptoms for the secondary response
- B and T cells activated for primary, memory cells and T cells activated for secondary
- Low rate of antibody production for primary, high rate of antibody production for secondary
- Only a few antibodies prodcued for primary, large number of antibodies produced for secondary
- Time between pathogen exposure and antibody production is long for primary, short for secondary
What is an antibody?
A quaternary structure protein that is complementary in shape to a specific antigen and is produced in response to it
What is formed when an antibody binds to an antigen?
An antigen-antibody complex
What is the structure of an antibody?
Antibodies are Y-shaped glycoproteins made up of 4 polypeptide chains, held together by disulfide bridges
- They have two light and two heavy chains
- They are quartenary structure proteins
Antibodies have two regions. What are they called?
- Constant region
- Variable region
What is meant by the constant region on an antibody?
The part that remains the same for all antibodies and binds to receptors on cells such as B cells
What is meant by the variable region on an antibody?
The part that is different for each antibody as it binds to a specific antigen so its shape has to be specific and complementary
What is agglutination?
Where pathogens are clumped together which makes it easier for phagocytes to locate and destroy pathogens
How does agglutination occur?
Antibodies have two binding sites so they can bind to two pathogens at once which leads to them clumping together
