ICS - Immunology Flashcards by Becky Cooper

What is the difference between innate and adaptive immunity?

Innate = non-specific, instinctive, does not depend on lymphocytes
Adaptive = specific, acquired, requires lymphocytes

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What are haematopoietic pluripotent stem cells?

Haemocytoblasts = the stem cell that every blood cell in the body originates from

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What is the most important cell type in innate immunity?

Neutrophils - phagocytosis (contain lysosomes that secrete toxic substances)

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What is the role of monocytes and which type of immunity are they useful in?

Remove anything foreign (microbes) or dead

Innate (phagocytosis) and adaptive (Ag presentation)

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What is the role of macrophages and which type of immunity are they useful in?

Remove foreign (microbes) and self (dead/tumour cells)
Innate and adaptive
Phagocytosis and Ag presentation to T-cells

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What is the role of eosinophils and why are they needed in the immune system?

Parasitic infections and allergic reactions

Activates neutrophils, induces histamine release from mast cells and provokes bronchospasm

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What is the role of basophils and why are they needed in the immune system?

Parasitic infections and allergic reactions
Binding of IgE to receptor causes de-granulation releasing histamine
Very similar to mast cells

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What is the role of mast cells and why are they needed in the immune system?

Allergic reactions
Binding of IgE to receptor causes de-granulation releasing histamine
Only in tissues (precursor in blood)

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What is the role of T-lymphocytes and which type of immunity are they useful in?

Adaptive immunity
Recognise peptide Ag displayed presenting cells (APC)
4 main types: T helper 1, T helper 2, Cytotoxic T cell, T regulator

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What is the role of B-lymphocytes and which type of immunity are they useful in?

Adaptive immunity

Recognise peptide Ag displayed presenting cells (APC)

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What is the role of natural killer cells?

They recognise virus infected/tumour cells and kill by apoptosis

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What is the mode of action of complement?

Direct lysis
Attract more leukocytes to site of infection
Coat invading organisms

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What is the role of antibodies?

Hallmark of adaptive immunity - they bind specifically to antigen (Ag)
Immunoglobulins - soluble

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What are the 5 classes of immunoglobulins?

IgG - crosses placenta
IgA - predominant in mucous secretions such as saliva, milk and bronchiolar secretions
IgM - found in blood, primary response
IgD - transmembrane monomeric form is present on mature B cells
IgE - associated with allergic response (basophils/mast cells express IgE-specific receptors, binding triggers release of histamine)

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Define antibody (Ab)

Protein produced in response to an antigen. Can only bind with antigen that induced its formation (specificity)

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Define antigen (Ag)

A molecular that reacts with preformed antibody and specific receptors on T and B cells

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Define epitope

The part of the antigen that binds to the antibody/ receptor binding site

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Define affinity

Measure of binding strength between an epitope and an antibody binding site

Define cytokine

Proteins secreted by immune and non-immune cells. Substances produced by one cell that influence the behaviour of another

What is the role of interferons?

Induce a state of antiviral resistance in uninfected cells and limit the spread of viral infection

What is the role of interleukins?

Can cause cells to divide, to differentiate and to secrete factors

What is the role of colon stimulating factors (CSF)?

Involved in directing the division and differentiation on bone marrow stem cells

What is the role of tumour necrosis factors?

Mediate inflammation and cytotoxic reactions

What is the role of Chemokines?

They attract leukocytes to sites of infection/inflammation by binding to specific receptors on cells

Give 3 examples of anatomical barriers

Skin Sebum (skin secretions) Intact skin (prevents penetration)

Give 3 examples of mucous membranes (physical barriers)

Saliva Mucous secretions Low pH and commensals of vagina

Give 3 examples of physiological barriers

Temperature pH Gastric acidity

Define inflammation

A series of reactions that bring cells and molecular of the immune system to sites of infection or damage

What are the 3 hallmarks of inflammation?

Increased blood supply Increased vascular permeability Increased leukocytes trans-endothelial migration 'extravasation'

What is the difference between acute and chronic inflammation?

Acute = complete elimination of a pathogen followed by resolution of damages, disappearances of leukocytes and full regeneration of tissue Chronic - persistent, un-resolved

What are the 6 stages of phagocytosis?

``` Binding Engulfment Phagosome formation Lysosome fusion (phagolysosome) Membrane disruption Antigen presentation/ secretion ```

What is the role of major histocompatibility complexes (MHC)?

Display peptide from self/non-self proteins on the cell surface - invasion alert MHC I - glycoproteins on all nucleated cells MHC II - glycoproteins only on APC MHC III - code for secreted proteins

What is the role of secreted and circulating pattern recognition receptors?

Lectins and collectins activate complement and improve phagocytosis

What is the role of cell-associated pattern recognition receptors?

Present on the cell membrane and recognise a broad range of molecular patterns Toll-like receptors (TLRs) are the main ones

What are the 3 types of vaccines used?

Whole killed, toxoids, live attenuated

Define passive immunity

A short-term immunity which results from the introduction of antibodies from another person or animal

Define vaccine

Antigenic substance prepared from the causative agent of a disease

Give 3 reasons a vaccine may not be able to be produced for a specific pathogen

Pathogen is too hard to grow Killed pathogen is not protective Impossible to obtain attenuated and suitably immunogenic strain

What are the 5 stages of vaccination?

1. Engage the innate immune system 2. Danger signals that activate the immune system, triggers such as molecular fingerprints of infection - PAMPs 3. Engage TLR receptors 4. Activate specialist APC 5. Engage the adaptive immune system

Give 4 hallmarks of cancer

Evade apoptosis Limitless replication potential Invade tissues Escape immune surveillance

What is cancer immune-surveillance?

The immune system can recognise and destroy nascent transformed cells, normal control

What is cancer immunoediting?

The immune system can kill and also induce changes in the tumour resulting in tumour escape and recurrence

Give 3 examples of antigen-presenting cells

Macrophages, dendritic cells, B cells

What type of white blood cell is measured for HIV diagnosis and what level indicates AIDS?

CD4+ count, <200