Adaptive Immunity Flashcards
What are the two kinds of immunity?
Innate and adaptive
What is the kind of cell that sees the pathogens first?
Dendritic cells and macrophages
If a a bacterial infection is present then which cells are the first ones to appear?
Neutrophils
In what case are natural killer cells and lymphocytes the first ones to appear?
Viral infections
What are the cellular components of adaptive immunity?
T-cells and B-cells
What kind of immunity do T-cells provide?
Cell-mediated immunity
Which kind of cells provide humoral immunity?
B-cells
What receptors do B-cells have?
B-cell receptors which activate immunity
What receptors do T-cells have?
T-cell receptors to detect antigens
Where are T-cells and B-cells developed?
T-cells; thymus
B-cells; bone marrow
What kind of receptors do monocytes have?
CD44
What happens when CD44 receptors get engaged?
They get engaged when they come in contact with the antigen, causes receptors to enlarge and change the structure and function of the monocyte developing it to a macrophage.
Where are B-cells and T-cells most commonly found?
The lymph-nodes
Where are the receptors of a phagosome?
Intracellularly
Why is the swelling response of inflammation beneficial?
Leakage fluid accumulates in the lymph nodes through the lymphatic system, that also allows dendritic cells to move towards the lymph-nodes too.
Why is it important that an infection does not escape from the lymph-nodes to the circulatory system?
If it is in the blood-stream it will have access to all tissues and organs.
What are antigens?
Any substance that can trigger the immune system of the body
What are examples of pathogenic-antigens?
Proteins, nucleic acids, carbohydrates and lipids.
What are self-antigens?
The individual’s own proteins, nucleic acids, carbohydrates or lipids that can act as antigens in other people
What happens if an antigen is too small, what is considered too small?
A molecular weight less than 10000 Da
It will not trigger a response unless attached to a carrier
What are small antigens known as?
Haptens
What are examples of haptens?
Cosmetics, hair dyes, animal dander, chemicals
What is immunogenicity?
The ability to generate an immune response
What is antigenicity?
The ability to attach to an antigen, may or may not cause an immune response
Which immunogens are antigenic?
All immunogens are antigenic but not all antigenic substances cause an immune response
What are mature T-lymphocytes and where are they found?
They are T-cells that have undergone the process of maturation, they are not in cells, they are either in the circulation or the lymph nodes.
After how many days would there be an increase in lymphocytes if an infection is present?
7 days
What are mature-naive lymphocytes?
They are B and T cells that have gone through the whole maturation process but they are yet to be exposed to the pathogen.
Where do the lymphocytes destined to become T-cells go?
They migrate through the blood to the thymus and develop immunocompetence there
Where do B-cells develop immunocompetence?
In the red bone marrow
Which kind of lymphocytes leave the thymus and bone marrow?
Immunocompetent but still naive lymphocytes
Where do lymphocytes encounter their antigen and become activated?
The lymph nodes, spleen and other lymphoid tissues
When do lymphocytes mature?
When they come in contact with their antigen
What do mature immunocompetent lymphocytes do?
They circulate continuously in the bloodstream and lymph and through-out the lymphoid organs of the body.
What are the factors influencing antigen strength?
Molecular type
Deviation from self
Size
Heterogeneity
Capacity to be broken down
What is the molecular type order from the most antigenic to the least?
Proteins, CHO, Lipids, DNA/RNA
How does deviation from self affect antigenicity?
How does size affect antigenicity?
The greater the weight, the greater the chance it activates an immune response
What are antigen epitopes or determinants?
Small regions that allow for specific recognition of antigen, where antigens attach
What are the two categories under heterogeneity that can affect antigenicity?
Structure
Composition
What is the B-cell receptor made up of?
The antibody associated with lgβ and lgα chains
What are the light chains linked with?
Disulphide bond
Why do the chains at the end of the BCR require proteins?
To transport to the nucleus, cannot do it themselves because they are too small
What are the different examples of antigens?
Microbes
Non-microbes
Lipids
Hapten
What are microbe antigens?
Capsules,
Cell walls,
Toxins,
Viral capsids,
Flagella
What are non-microbe antigens?
Pollen
Egg white
Red blood cell surface molecules
Serum proteins
Surface molecules from transplanted tissue
What are lipid antigens?
Lipids and nucleic acids are mainly antigenic when combined with proteins or polysaccharides
What are hapten antigens?
Small foreign molecules that are NOT antigenic, must be coupled to a carrier molecule t be antigenic.
When will the hapten be recognised?
Once antibodies are formed
Why does immunogenicity increase based on the number of epitopes?
More epitopes, more antigens able to attach
Which kind of epitope is recognised immediately because of its straights sequence?
Linear epitope
What is a cryptic epitope?
It can only be reached once phagocytosis is done and the protein has denatured
What do B-cells recognize? How?
Free soluble antigen in the blood or lymph by their receptors
What are B-cell receptors?
Membrane-bound immunoglobulins
What are the two possible processes after cell proliferation?
Clone of plasma cells
Clone of memory cells
Do small amounts of a virus elicit an immune response?
No, not a lot of antigens so no immune response
What is the process of B-cells?
Each B-cell has different antigen receptors (one antigen per receptor)
In the presence of cytokines, this B-cell is stimulated to divide (clonal expansion)
It will divide into plasma cells or memory B-cells
Where do the cytokines come from?
T-cells
Why do plasma cells have no receptors?
Their main purpose is to identify the antibody then die off
What is the main function of plasma cells?
To secrete antibodies
How is adaptive immunity mediated?
Through antibodies or immunoglobulins
What are the five major classes of antibodies?
IgM
IgA
IgG
IgE
IgD
What is the function of the antibodies?
To recognise and bind corresponding antigen
What is the structure of the antibody?
There are 2 N-termini and 1 C-termini
There are 2 identical heavy and light chains in the N-termini
The C-termini chains have two carbohydrates attached
Everything is linked by disulphide bonds
What are antibodies composed of?
Polypeptides with variable and constant regions
What are the variable regions?
Involved in antigen recognition & binding
What are the constant regions?
Interact with immune system components
What protein is involved in the proteolytic cleavage of the IgG?
Papain, which forms three structures
What does papain produce?
The two Fab and one Fc segments
What happens after the protein-protein interaction (antigen-antibody)?
Changes the structure and conformation of the Fc fragment which exposes the binding site and allows Fc to bind to antibody
What determines the Ab type?
H-chain constant region
What are the heavy chain isotopes?
γ heavy chain
μ heavy chain
δ heavy chain
α heavy chain
ε heavy chain
What are the subtypes of γ heavy chain?
IgG1 to IgG4
What are the subtypes of the α heavy chain?
IgA1 and IgA2
Where does the variable segment of the H chain lie in antibody synthesis?
Upstream of the constant region of the H chain
When does transcription take place?
A point before the Cγ3
What happens to the RNA during antibody synthesis?
Spliced in 2 ways
m-RNA for μ heavy chain
What happens to the m-RNA for μ heavy chain?
IgM or δ-heavy chain
What does δ-heavy chain become?
IgD
What does polyadenylation splicing produce?
IgM or IgD
