Immunology- Introduction to specific immunity Flashcards
What are the -physical barriers -inflammatory response -Antimicrobial response - cells in the innate immune system?
physical barrier- Skin, mucous membrane inflammatory response- histamine Antimicrobial protein- complement Cells- Neutrophils macrophages eosinophils NK cells
What are the 2 types of specific adaptive immunity?
Humoral
Cell mediated
Define the simple pathway for humoral immunity?
CD4 helper T cell stimulates B cell to release antibodies against extracellular pathogens
What pathological components are destroyed in humoral immunity?
Parasites and worms
extracellular bacteria
fungi
bacterial toxins
Define the simple pathway for cellular immunity?
CD4 helper T cell stimulates activation of CD8 cytotoxic t cells which lyse cells infected with intracellular pathogens.
What pathological components are destroyed in cellular immunity?
Intracellular bacteria
Viruses
Viral Protein
Explain the immune response timeline for innate immunity?
Infection within the first 4 hours
Allows recognition from non specific and broadly specific effectors.
Ultimately leads to the removal of the infectious agent.
Explain the immune response timeline for early induced innate response immunity?
Infection within 4- 96 hours.
This causes the recruitment of effector cells
Recognition of PAMPS and activation of effector cells and inflammation
Ultimately removal of infection agent.
Explain the immune response timeline for adaptive immunity response?
Infection over 96 hours
causes transport of antigens to lymphoid organs
recognition of naive b and T cells
Causes colonial expansion and differentiation to effector cells
Removal of infectious agent.
Where do B cells develop?
Bone marrow
What is the stages of T cell development and maturation?
Pre T cells develop in the bone marrow but then migrate to the thymus gland to become mature.
Define cell mediated immunity?
Involves CD8 t-cells proliferating into cytotoxic T cells which is largely associated with targeting intracellular pathogens.
Define antibody mediated immunity?
involved in the transformation of B cells into plasma cells.
The plasma cells then synthesise and secrete immunoglobulins and antibodies which will bind to specific antigens.
These are aided via CD4 helper T cells
Define an ANTIGEN?
Non-self molecular configuration.
What is the function of an antigen?
Activate the adaptive response of antibody production
Define immunogenicity?
Ability to induce a response mediated by the production of specific t-cells or antibodies.
Define reactivity?
Ability to react with antibodies or specific t- cells.
What do t- cells respond to?
Protein antigens
What do B-cells respond to?
Proteins, lipids, carbohydrates and nucleic acids.
How do antigens come into contact with the immune system?
By either being carried via the blood into the spleen or the lymph to the lymph nodes. Where they are trapped by reticular fibres.
What are MHC molecules?
MHC are molecules which are expressed on the surface of cells important in immune response.
They guide recognition of antigen by t-cells
They bind epitopes of antigens and present them to t-cell
What are the two types of MHC
MHC 1
MHC 2
What Is MHC 1
Built into the plasma membrane in all body cells besides RBC
What is mHC 2
Found on membranes of antigens
How is antigen processing achieved?
B/T cells recognising the antigen
B cells can recognise antigens in the body fluids
T cells can only recognise antigens presented to them in combo with an MHCA
Where do MHC proteins arise from
Self proteins
How is an MHC molecule stabilised and incorporated into the cells membrane as a self antigen?
Protein fragments are associated with a peptide binding groove of a newly synthesise MHC molecule.
What happens when an mHC molecule arises from a non self source?
MHC will express a non self antigen
What are the 2 ways you can process foreign antigens?
Exogenous antigen processing
Endogenous antigen processing
How do APCs present exogenous antigens in association with MHC.
- Phagocytosis or endocytosis occurs of the antigen
- Causes the digestion of antigens into peptide fragments.
- Vesicles containing peptide fragments and MHC 2 complex molecules fuse
- Peptide fragments bond to mHC 2 complex
- Vesicle undergoes exocytosis and antigen MHC 2 complex are inserted into the plasma membrane
What does exogenous antigen processing refer to?
Antigens found within bodily fluids
How are antigens processed exogenously?
APCs such as macrophages ingest the antigen which is digested into protein fragments which are transferred to a small vesicle like structure.
APCs also synthesise the MHC 2 molecule that are also packages into vesicles so that the MHC 2 line the inner membrane of the vesicle.
2 vesicles fuse together and undergo excosytosis. causing MHC 2 complex to be presented on the outside of csm.
After processing the APC migrates to lymphatic tissue where antigen can be presented to the T cell
How are antigens processed endogenously?
Endogenous antigens are produced within the cell and fragments of these become associated with MHC 1 molecules
This antigen MHC 1 complex moves to the cell membrane where it is displayed on the surface antigen.
Why do t -cells not recognise free antigen?
They only recognise antigens inside the body.
They recognise the epitopes of antigens when presented with an MHC Complex on the surface of other cell sin the body.
Explain the process of T-cell antigen recognition?
Epitope recognised by t-cells receptors are often buried
The antigen must first be broken down into peptide fragments.
Epitope binds to a self molecule MHC
The T cell receptor binds to MHC and epitope peptide
What is the 2 step process of T cell activation?
Initial binding of a T cell with specific antigen
Co-stimualtion
Define costimualtion?
Different co stimulants activate T cells. If fully activated APC and co stimulants T cells will proliferate and diffrenictae.
What does a lack of co stimulates do
Causes anergy
what are the 3 main types of t cells
Memory
Cytotoxic T cells
Helper T cells
How do helper T cells develop
They are developed from CD4 proteins.
How do HELPER T cells contribute to the T cell activation?
Helper T cell recognise the antigen mHC complex and it costimulated by complimentary molecules on the APC which starts secreating cytokines
What does interlukein IL-2 DO?
It triggers t -cel proliferation and enhance proliferation of the B cells and nk cells
What is the role of cytokines?
Enhance the immunocompetent cell function.
Small hormones either stimulate to inhibit the cellular diffrenfitison
Where are cytotoxic T cells derived from
CD8
What do cytotoxic cells do?
They recognise antigen MHC1 complexes on virus infected cells and on some surfaces of cancer cells
How do cytotoxic T cells destroy target cells?
By secreating
- Poroforin
- Lymphototoxins
- Gamma interferons
What is the role of memory cells?
They remain after an infection to allows rapid immune response when immune system comes across same antigen at higher amplitude.
