Immune system Flashcards
Physical barriers
skin
Mucous membranes of the mouth, respiratory tract, GI tract, and urinary tract
Bronchial Cilia
chemical barriers
The relatively low pH of parts of the body.
Skin – pH 5.5 Gastric acid – pH 1-3 Vagina – pH 4.4
Antimicrobial molecules.
IgA – present in tears, saliva and mucous membranes
Lysozyme – present in sebum, perspiration and urine
Mucus – present in mucous membranes
Beta-defensins – present in epithelia
Pepsin – present in the gastrointestinal tract
biological barriers
Normal flora compete with pathogens for attachment sites and resources, and may even produce antimicrobial chemicals. In addition to this, a number of them also produce essential vitamins, such as Vitamin K and B12.
found within: Nasopharynx. Mouth and throat Skin GI tract Vagina
physiological barreies -expel from body
processes that occur in response to pathogens in order to remove them from the system these barriers are: Diarrhoea Vomiting Coughing Sneezing
Innate cells have PRR( pattern recognition receptors) and recognise what
PAMP( pathogen associated molecular pattern
Role of CRP
coats pathogens and makes more visible to phagocytes
What is the complement system
system of plasma proteins that can be activated directly by pathogens or indirectly by pathogen based antibodies
C3b
Opsonin
C5a
chemotaxis and attraction of macrophages and neutrophils and also activate mast cells along with C3a
C3a, (C4a + C5a)
bind to mast cells/basophils which causes degranulation. Histamine and serotonin increase vascular permeability. Promotes pro-inflammatory cytokines
What is MAC ( membrane attack complex )
and what type of pathogen can it not attack
ruptures bacterial cell wall which leads to cell lysis (although not in gram positive bacteria or fungi)
Briefly describe classical pathway
C1q binds to pathogen or antigen-antibody complex forms C3 covertase which splits C3 into C3a and C3b
briefly describe the lectin pathway
manse binding lectin binds to mannose(carb) on pathogen surface forms C3 covertase etc
briefly describe the alternative pathway
C3b joins with another factor to make C3 covertase
Autocrine
cytokine back to molecular mole of same cell
Paracrine
CT local tissue - another cell
endocrine
bloodstream
What interleukin activates T helper 1 cells from naive T cells
IL-12
What interleukin activates t helper 2 cells from naive T cells
Il-4
4 steps of gram staining
application of crystal violet dye - purple
application of iodine
alcohol wash for decolorisation
application of sarfarin which is a counter stain so turns pink
What is a retrovirus such as HIV
retrovirus, meaning it carries the enzyme reverse transcriptase, which allows the infected cell (often a T lymphocyte) to make virus DNA from virus RNA. The DNA is then inserted into the cell’s own DNA and acts as a gene.
What is active immunity
Immunity you develop after being exposed to an infection or from getting a vaccine
What is passive immunity
Immunity you acquire from someone or something else
Natural active immunity
Antibodies made after exposure to an infection
artificial active immunity
Antibodies made after getting a vaccination
natural passive immunity
Antibodies transmitted from mother to baby (eg: via mothers milk)
artificial passive immunity
antibodies acquired from an immune serum medicine
What type of T cell is defence against intracellular bacteria and viruses - cell mediated response ( started by a cell)
T helper 1 cell
Which type of T cell is defence against extracellular bacteria and parasites ( humeral mediated response)
T helper 2 cell
Which type of T cell is involved in the pro inflammatory response and involved in chronic inflammation and autoimmune disease?
T helper 17 cell
What interleukin activates t helper 17 cells
IL-6
Which MHC molecule to CD8 killer cells recognise viral infected host cell
MHC-1
What cells are MHC-11 on
Dendritic, naive T cell , Th2 cell, activated B cell, plasma cells
What cells are MHC -1 on
all nucleated cells
CD8 killer cells use perforin and gramenzymes what do theses do>
punch hols in the CM and destroy the cell
What type of cells down regulates TH1 and TH2, stopping activation and return to normal ( IL-10)
T-reg cells
What cells do Th1 cells activate and with what cytokines activate them?
B cell- IFN-gamma then goes to plasma cell
marcrophage - IFn-gamma
Nk cell - IFN-gamma, IL-2
CB8 cell( cytotoxic) - IFN-gamma, IL-2
What cells to TH2 activate and with what cytokines activate them?
naive B cell - IL4 - plasma cells and IgE
macrophage -IL4
eosinophil -IL3
basophil, mast cell -IL3
5 types of antibodies
Immunoglobulin (Ig) M – secreted first and has 10 potential binding sites
IgG – highest opsonization and neutralisation rate. Most abundant and produced secondary to IgM
IgA – expressed in mucosal tissues, serum, saliva, breast milk and intestinal fluid. Forms dimers after secretion
IgE – rare and only responds to parasites and allergies
IgD – functions unknown
What is the most abundant antibody?
IgG
What anybody is secreted first?
IgM
What antibody is secreted in breast milk?
IgA
Functions of antibodies (3)
Opsonisation: Binding of an antibody to an epitope on a pathogen, attracting phagocytes
Neutralisation: Bind to toxins and blocks pathogens from entering the cell
Agglutination: Antibody binds to more than one pathogen causing an eventual build up, this makes phagocytosis easier
where does T cell selection and tolerance occur
In the thymus to prevent autoimmune disease
TH1 Cells release IFN-gamma what does this do ?
activates B cells to make plasma cells - cell mediated response
How do TREG cells stop/turn off immune system
by releasing anti-inflammatory cytokines
where do B cells develop and mature
bone marrow
What does B cell tolerance prevent
attacking self tissue
What is anergy
frozen state before cell apotosis
What cell and how does it change the type of antibody produce from IgM to IgG
isotope switching with Th2 tell activated B cells via cytokines
4 roles of antibodies
Toxin and pathogen neutralisation - prevents toxin damaging tissues and pathogen entering cell
Pathogen opsonisation - highlights
antibodies and acute inflammation - activation of complement and in turn masts ells which release chemicals causing inflammation
Antibody mediated cell toxicity - cytotoxic cells bind to anybody and release enzymes for apoptosis
Where Is the antibody IgE found
connective tissue and mast cell
what antibody produced first in second response
IgG
how are memory cells made?
clonal expansion in semi-active state
function of acute phase proteins made in the liver? Il-6
primarily opsonisation
The pattern recognition receptors on macrophages recognise what on bacteria
PAMPS- pathogen - associated molecular pattern
4 stages of phagocytosis
attachment
ingestion
killing
degradation
what is an oxidative burst
neutrophils kill microbes by the production of reactive oxygen species
what cytokines Activating T cells- Cell mediated response
IL-12
IL-2
Interferon-IFN-γ
Tumour Necrosis Factor- TNF-α
what cytokines Antibody production- Humoral response
IL-4
IL-5
IL-13
what cytokines Anti- inflammatory
Turn off the cells
IL-10
Transforming Growth Factor-TGF-β
C5b-9
lysis of microbe
what are acute phase proteins
bacteria induce macrophages which IL-6 which acts on hepatocytes in the liver and induce synthesis of acute phase proteins
mannan binding lectin binds mannose residues on bacterial surface so acts as an opsonin
also CRP
which cells have an MHC 2 molecule
Antigen presenting cells- Dendritic cells, Macrophages, B cells
what is this the process of
Dendritic cell to CD4 interaction
activated T cell to B cell interaction - MHC 11
activated T cell to B cell interaction via isotope switching
B cell activation
