Immune system Flashcards by HARRY RICHARDSON

Physical barriers

skin
Mucous membranes of the mouth, respiratory tract, GI tract, and urinary tract
Bronchial Cilia

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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

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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

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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

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Innate cells have PRR( pattern recognition receptors) and recognise what

PAMP( pathogen associated molecular pattern

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Role of CRP

coats pathogens and makes more visible to phagocytes

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What is the complement system

system of plasma proteins that can be activated directly by pathogens or indirectly by pathogen based antibodies

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C3b

Opsonin

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C5a

chemotaxis and attraction of macrophages and neutrophils and also activate mast cells along with C3a

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C3a, (C4a + C5a)

bind to mast cells/basophils which causes degranulation. Histamine and serotonin increase vascular permeability. Promotes pro-inflammatory cytokines

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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)

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Briefly describe classical pathway

C1q binds to pathogen or antigen-antibody complex forms C3 covertase which splits C3 into C3a and C3b

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briefly describe the lectin pathway

manse binding lectin binds to mannose(carb) on pathogen surface forms C3 covertase etc

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briefly describe the alternative pathway

C3b joins with another factor to make C3 covertase

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Autocrine

cytokine back to molecular mole of same cell

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Paracrine

CT local tissue - another cell

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endocrine

bloodstream

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What interleukin activates T helper 1 cells from naive T cells

IL-12

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What interleukin activates t helper 2 cells from naive T cells

Il-4

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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

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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.

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What is active immunity

Immunity you develop after being exposed to an infection or from getting a vaccine

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What is passive immunity

Immunity you acquire from someone or something else

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Natural active immunity

Antibodies made after exposure to an infection

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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