L18: Immunology I Flashcards
3 functions of the immune system
1) Respond to infection by micro-organisms
2) Repair damaged tissues
3) Retard cancer development
How does the immune system represent a number of surveillance mechanisms?
Capable of recognising self vs non-self
- Secrete protective substances into bodily fluids
- Launch cellular response
2 parts of the immune system
1) Innate Immunity
2) Adaptive Immunity
Features of innate immunity
1) Non-specific
2) Rapid
3) Response to infections
4) Can be humoural/cell-mediated
Define humoural
Secreted things
Define cell mediated
Cells that target damaged site
Features of adaptive immunity
1) Specific
2) Slow to develop
3) Response to infections
4) Humoural/cell mediated
Are cells of the innate response highly or slightly phagocytic?
Highly phagocytic
What proteins does the cells of the innate reponse contain that destroy engulfed bacteria, cellular debris or foreign particulate matter
Lysosomal & microbiocidal proteins
Names for macrophages in liver
Kupffer cells
Names for macrophages in bone
Osteoclasts
Names for macrophages in kidney
Mesangial cells
Names for macrophages in brain
Microglia
Describe neutrophil action
They only survive for only a few days, constantly replaced
Two forms of ‘killer’ cells
Natural killer cells
Eosinophils
Describe natural killer cells
Attach to virally infected cells/tumour cells by causing pores to form in the target cell membrane inducing a apoptotic death
Describe eosinophils as a ‘killer’ cell
Contain granules with cytotoxic proteins that attach to, and kill, parasites
Are adaptive immune cells or innate immune cells slower to react?
Adaptive Immune Cells
Define antigens
A toxin or foreign substance which induces an immune response in the body
Induce a T cell / B cell response
Can be a protein, lipid, carbohydrate or nucleic acid
Define antibodies
Glycoprotein that interacts with a specific antigen
- Can neutralise the antigen to induce phagocytosis by macrophages
Can adaptive response be both cellular & humoural?
Yes
Why are lymphocytes adaptive immune cells?
Can differentiate into memory cells, which can respond faster & more efficiently the next time the same pathogen invades
2 functional classes of lymphocytes
1) B cell
2) T cell
Where does lymphocytes circulate & become activated?
Circulate in blood & lymph and become activated in secondary lymphoid organs
Where does B cells arise & mature in?
Arise in bone marrow
Mature in bone marrow
Where does T cells arise & mature in?
Arise in bone marrow
Mature in thymus
Where are B cells & T cells activated in?
Secondary lymphoid organs
Function of B cells
Secrete antibodies specific to target antigen
Activated by antigen & helped along by Helper T cells, secrete antibody when activated
Function of T cells
Induce a cell-mediated adaptive immune response
Direct & recruit other cells of immune system as well as attacking diseased cells directly
What is long term immunity maintained by in B cells?
Memory B cells
What is long term immunity maintained by in T cells?
Memory T cells
What receptors are responsible for recognition of antigen?
Specific T cell receptors (TCR)
4 functional subsets of T cells
1) Helper T cells
2) Cytotoxic T cells
3) Regulatory T cells
4) Memory T cells
Function of Helper T cells
Activate B cells
Function of Cytotoxic T cells
Kill infected cells (antigen)
Function of Regulatory T cells
Help module responses
What can antibodies do when it is secreted?
Neutralise the pathogen
Facilitate uptake of phagocytes (opsonization)
Define opsonization
An immune process which uses opsonins to tag foreign pathogens for elimination by phagocytes
2 functional subsets of B cells
1) Plasma cells
2) Memory cells
Define VDJ recombination
Somatic recombination occuring in developing lymphocytes during early stages of T & B cell maturation
Role of FC region on antibody
Signals macrophages when binded to antibodies
When does lymphocyte activation occur?
When lymphocytes (B cells or T cells) are triggered through antigen-specific receptors on their cell surface
B cells
Lymphocyte activation in B cells
- Surface immunoglobin binding to B cells
- Clonal expansion occurs creating plasma cells & memory B cells
T cells
Lymphocyte activation in T cells
- Antigen presentation via antigen presenting cell
- Clonal expansion occurs
- Producing T helper cell, cytotoxic cells & memory T cells
2 tissues of the immune system
Primary Lymphoid Tissues
Secondary Lymphoid Tissues
Primary Lymphoid Tissues
Immature lymphocytes acquire the capacity for antigen recognition
Secondary Lymphoid Tissues
Site of lymphocyte activation
Describe the thymus
Encapsulated organ with 2 lobes located in the lower
- Site of T cell maturation
1) Aquisition of T cell immunocompetence
2) Development of immunological self tolerance
What are lymph nodes?
Small organs found in groups/chains in sites where lymphatic vessels drain to an anatomic region
2 functions of the lymph nodes
1) Phagocytic cells act as non-sepcific filters of particulate matter
2) Location where lymphocytes interact with new antigens & APCS, facilitate activation of an immune response
Structure of lymph nodes
Surrounded by fibrocollagenous capsule, surface is penetrated by a number of afferent vessels
Function of follicles in lymph nodes
Regions of B cell activation
What does germinal center in lymph nodes consist of?
Activated dividing B cells, with a few T cells
What is the mantle zone in lymph nodes?
Resting B cells
Function of the spleen
Responsible for immunological responses against blood antigens
- Removes aged/defective blood cells
2 pulp in the spleen
1) Red pulp
2) White pulp
Function of red pulp in the spleen
Responsible for filtering blood
Function of white pulp in the spleen
Immunological region of the organ
What does MALT stand for?
Mucosa Associated Lymphoid Tissue
