Cells of the Immune System Flashcards
What are the 3 types of granulocytes
Neutrophils
Eosionphils
Basophils
What are there most common form of granulocyte
Neutrophils
How do neutrophils come into contact with and destroy bacteria etc.
They circulate in the bloodstream and can phagocytose bacteria and dat
What do eosinophils do
They are important for defence against parasites and are also involved in allergic reactions
What do basophils do
Important against parasites and are involved in allergic reactions
What is the difference between eosinophils and basophils
Eosinophils - eosin stain used on them
Basophils - Basic dye used to stain them
What do mast cells do
Important against parasites and bind to IgE that leads to crossing linking between the IgE receptors and an antigen that leads to calcium influx, degranulation and histamine release in an allergic response
What do monocytes develop into
Macrophages
Where are monocytes found
In the bloodstream and tissues
What do monocytes and macrophages do
They coordinate an immune response by telling other immune cells that there’s a problem.
Macrophages also recycle dead cells like RBCs and clear away cellular debris
What do neutrophils do at the site of local tissue injury
Accumulate at site in minutes and tell other neutrophils to swarm site using lipids and mediators.
Their movement and signals tell macrophages and monocytes to surround the neutrophil cluster and for a tight wound seal
What do dendritic cells develop from
Monocytes
What is the main function of dendritic cells
They are an important antigen presenting cell that process large molecules into readable fragments recognised by B and T cells.
What is an examples of an intracellular antigen
A virus
What kind of immunity are natural killer cells (Innate/adaptive)
Both BITCH
What do natural killer cells do
Recognising and killing virus infected cells or tumour cells
How do natural killer cells kill virus infected cells and tumour cells
They have intracellular compartments called granules that are filled with proteins that can form holes in the target cell and also cause apoptosis
What is the main difference between apoptosis and necrosis
Apoptosis doesn’t release danger signals that can lead to greater immune activation and inflammation
What are the functions of B cells
They present antigens to T cells and produce antibodies to neutralise infectious microbes and the toxins produced by them
What are the major roles of antibodies
- Neutralisation occurs when the pathogen, because it is covered in antibodies, is unable to bind and infect host cells
- In opsonisation an antibody bound pathogen serves as a red flag to alert immune cells like neutrophils and macrophages to engulf and digest the pathogen
- Complement is a process for directly destroying, or lysing, bacteria
What are the 2 ways that antibodies can be expressed
B cell receptors that sit on the surface of a B cell is actually an antibody
B cells also secrete antibodies to diffuse and bind to pathogens
Why is the dual expression of antibodies important
As the bacterium is recognised using the antibodies on the B cell surface and the antibodies that the B cell secretes is the action taken that actually kills the pathogen
What categories can an antibody fall into
IgM IgD IgG IgA IgE
What does Ig stand for in reference to antibodies
Ig = Immunoglobulin = antibody
What are the roles of each category of antibody
- IgM = Important for complement activation
- IgG = important for neutralisation, opsonisation and complement activation
- IgA = essential for neutralisation in the GI tract
- IgD = the B cell receptor
What are the 2 categories of T cells
CD8+ T cells or CD4+ T cells
What is the difference between the types of T cell
Based on which protein is present on the cell’s surface
What do T cells do
Killing infected cells and activating/recruiting other immune cells
What are CD8+ T cells also called
Cytotoxic T cells
What do Cytotoxic T cells do and how do they do it
They recognise and remove virus infected cells and cancer cells by using granules containing cytotoxins that cause apoptosis, cus of the potency the release of these granules is tightly regulated by the immune system
What are the major CD4+ T cell subsets
TH1, TH2, TH17 and treg
TH - T helper cell
What are the roles of TH1 cells
Important for co-ordinating immune responses against intracellular microbes, especially bacteria. They produce and secrete molecules that alert and activate other immune cells like bacteria ingesting macrophages
What are the roles of TH2 cells
Important for co-ordinating immune responses against extracellular pathogens like helminths by alerting B cells, granulocytes and Amsterdams cells
What are the roles of TH17 cells and why are they called TH17 cells
Called TH17 for their ability to produce interleukin 17, a signalling molecule that activates immune and non-immune cells. TH17 cells are important for recruiting neutrophils
What are the roles of Tregs (regulatory T cells)
These monitor and inhibit the activity of other T cells and prevent adverse immune activation and maintain tolerance, or the prevention of immune responses against the body’s own cells and antigens
What are cytokines
Small proteins with diverse functions, there are several categories that are important fo immune cell growth, activation, function and Ig class switching
What do colony-stimulating factors do
They are essential for development and differentiation
What do interferons do
Needed for immune cell activation:
Type I - Mediate antiviral immune responses
Type II - Important for antibacterial responses
What do chemokines do
Made in specific locations of the body or at a site of infection to attract immune cells - different chemokines = different immune cell recruitment
What are tumour necrosis factors (TNFs)
Family of cytokines that stimulate immune cell proliferation and activation. Needed to activate inflammatory responses so drugs like TNF blockers are used to treat a variety of disorders like some autoimmune diseases
Where can you find Toll-like receptors (TLRs)
On innate immune cells like macrophages and dendritic cells, on the cell surface or in intracellular compartments because microbes may be found in the body or inside infected cells
Where can B cell receptors be found
On adaptive immune cells, on their cell surfaces and also as antibodies to neutralise pathogens
How are unique receptors for each B cell receptor generated
Genes for B cell receptors are randomly rearranged at specific cell maturation stages
Where can T cell receptors be found
Only on the cell surface of adaptive immune cells
How are unique receptors for each T cell receptor generated
Genes for T cell receptors are randomly rearranged at specific cell maturation stages
What is an MHC and HLA
MHC = Major histocompatibility complex HLA = Human leukocyte antigen
What do MHC Class I proteins do
These function as carriers to present antigens on cell surfaces (viral ones mainly)
CD8+ cells will recognise and kill infected cells
Where can you find MHC class I proteins
On almost all cell types except RBCs
Where are MHC class II proteins generally only expressed
On antigen presenting cells like dendritic cells and macrophages
What do MHC class II proteins do
Important to present antigens to CD4+ T cells
AY BAWS CAN I HABE DE NOTE PLZ
I think these CD4+ T cells can be activated by super antigens derived from bacteria
Where are MHC class II antigens derived from
MHC class II antigens are varied and include pathogen an host derived molecules
