Immunology Flashcards by Lucy Brown

What are the organs of the immune system?

Thymus- located behind breastbone, T-cells mature
Bone Marrow- Create WBCS
Lymph Nodes- produce and store cells which fight infection and disease
Spleen- Contains WBCS

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What is the lymphatic system?

Links key organs

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Purpose of lymphatic system

-transport clean fluids back to blood
-drain excess fluid
-removes debris from cells of body
-transport fats from digestive system

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What is the difference between innate immunity and adaptive immunity?

Innnate immunity is the first line of (non specific) defence whilst adaptive immunity is specific and acquired

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What are the three components of innate immunity?

-epithelium (physical barrier)
-innate cell subsets & complement
-Chemokines/cytokines

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What is the difference between chemokines and cytokines?

Chemokine-signalling molecule
Cytokine-Cell activation/proliferation

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What are the 2 cell types in adaptive immunity?

B cells
T cells

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What is adaptive immunity?

Provides neurological memory to fight infections again, 4-6 days

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What is inflammation?

Inflammatory reaction is aimed at eliminating inciting cause eg foreign agent

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What are examples of foreign agents?

-Invading microorganisms
-particulate material ( dentures, dust)
-altered self cells

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What are stages of an inflammatory response?

Initiation, response to harmful agent
Progression, containment of harmful agents
Amplification, modulation of immune response
Resolution, healing

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Eg of acute inflammation and severe inflammation?

Gingivitis and Periodontitis

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What is innate immunity?

The first line of defence against pathogens

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What are commensal organisms?

Organisms which don’t cause disease

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When does the innate immune response occur?

Between 1-4 days

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What is non-specific immune system driven by?

Innate

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How is the innate immune system effective?

Regular contact with the potential pathogens which are destroyed within minutes or hours, rarely causing disease

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How does epithelium present innate immunity?

Produces antimicrobial peptides
Produces cytokines/chemokines

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How does innate cell subsets present innate immunity?

Phagocytic cells
Antigen presenting cells

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What compounds do epithelium in the oral cavity produce?

Antimicrobial peptides
Immunoglobins
Lactoferrin
Lysosome
Cystatins

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What is the function of antimicrobial peptide?

To kill microbes (binding to cell wall, attaching to surface and disrupt membrane) and modulate the immune system.

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What is an example of an antimicrobial peptide?

B-defensins
Human neutrophil peptides
Cathelicidins
Psoriasin proteins

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What is the function of the secretory immunoglobin?

Form a protective layer in saliva, preventing pathogens from attaching to epithelium

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What is lactoferrin?

Glycoprotein that transports iron ions
but has antimicrobial activity. Present in saliva and
produced by neutrophils.

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What is lysozyme?

Present in saliva and produced by macrophages/neutrophils. Targets cell walls of bacteria.

What is cystatins?

Anti-protease activity and supports remineralization of the teeth

How do host cells recognise microbes?

Cells involved in immune responses have receptors for components of microorganisms ANTIGENS

What is the main receptor that recognises microbes and where are they present?

Toll-like receptors They are present on the surface plasma membrane or inside the cell.

Toll-like receptors present on cell membrane will recognise what?

Bacteria and fungal pathogens

Toll-like receptors present inside cell will recognise what?

Viruses

What are other types of receptors other than toll-like?

– Dectin and glucan receptors – Fungal recognition – NOD-like receptors – Bacterial recognition – Protease-activated receptors (PARs) - Microbial and allergen recognition

What are cytokines?

Signalling molecules that orchestrate immune responses.

What are the different functions of cytokines?

-Autocrine – alter behavior of cell from which they were secreted e.g., self-regulating * Paracrine – alter behavior of neighboring cells * Endocrine – enter circulation and alter behavior of distant cells

What are chemokines?

They tell cells where to go

What are chemotaxis?

Chemotaxis is the movement of a cell in a direction corresponding to a gradient of increasing or decreasing concentration of a particular substance (e.g., chemokines).

What is the main morphological change associated with dental caries?

Tooth decay

Where do all myeloid and lymphoid cells originate from?

In the bone marrow from a hematopoietic stem cell

Where do T cells mature?

Thymus

Innate immunity is the first line of which type of defence?

Non specific and effective

Adaptive immunity is the first line of which type of defence?

Specific and long lived

What is an example of a disease failing to resolve itself?

Chronic inflammation

What defence cell circulates in the blood and are precursors for macrophages?

Monocytes

When mast cells degranulate what do they release?

Histamine

What do neutrophils produce in order to encapsulate microbial cells?

NETS

What is the main role of dendritic cells?

Antigen presentation

Where is the site of dendritic cell- T cell interaction?

Lymph nodes

What is responsible for driving T cell differentiation?

MHC Proteins

What is the main role of B cells?

Production of antibodies

Epithelial cells, endothelial cells and fibroblasts are examples of what type of immune cell?

Non- professional immune cells

What is the name of the antibody produced at the epithelial surface and found in saliva?

Secretory Immunoglobin

B defensins and cathelicidins are examples of what?

Antimicrobial Peptides

The components of microbial cells that elicit an immune response are called?

Antigens

Dectin and glucan receptors are examples of PAMP's which recognise what?

Components of fungus

Cytokines which alter the behaviour of neighbouring cells can be described as?

Paracrine cytokines

What are chemokines primarily responsible for?

Recruitment

Why is cytokine/chemokine balance essential?

For optimal effectiveness

What do neutrophil granules contain?

Degradative enzymes and microbial substances

What do neutrophils attract to sites of inflammation?

IL-8

What are cell adhesion molecules?

Cells which control interactions between immune cells and endothelial cells

What are the three main families of cell adhesion molecules?

Selectins Integrins Immunoglobin superfamily

What is the importance of cell adhesion molecules?

Immune trafficking

What is the primary function of neutrophils?

Engulf and destroy evading pathogens

What is chromatin?

Clump of nucleic acids

What does activation of NETs stimulate neutrophils to do?

Release proteins and some genetic material (chromatin) to form extra cellular fibril matrix

What do M1 and M2 macrophages do?

M1 -proinflammatory cytokines M2- Inflammatory cytokines

What is the primary function of macrophages?

Phagocytosis and presentation of antigen to adaptive immune cells

What are the two types of antigen presenting cell?

-Non-professional (Epithelial cells/fibroblasts/endothelial cells) -Professional (Macrophages and dendritic cells)

What are granules and what may they contain?

Vesicles containing preformed mediators; eg Proteinases Antimicrobials

What is essential for the link between innate and adaptive immune system?

Phagocytosis and antigen presentation

What are the 4 enzymatic cascade systems of plasma?

Complement Kinins Coagulation factors Fibrinolytic system

What is 'complement'?

Collection of soluble proteins present in circulation of plasma which drives inflammation or opsonisation

What is oponisation?

Coating of pathogens by antibodies or complement proteins

What are the 3 pathways of 'complement'?

(1)Classical pathway – antibody attached to microbe (2) Alternative pathway – microbial cell wall (3) Mannose binding lectin pathway (MBL) – carbohydrates on pathogen surface

What are the functions of analphylatoxins?

Contraction of smooth muscle Capillary leakage

What enzymes are involved in the 3 pathways of 'complement'?

C3 and C5 Convertase

What are analphylatoxins?

Glycoproteins such as complement components C3, C4 and C5 (and their fragments) that drive immune responses Produced by mast cells

What immune responses to anaphylatoxins drive?

-Promote immune cell recruitment -Increase adhesion of cells to vessel walls -Induces granulation -Promotes cytokine production -Induces antigen presentation -Regulate adaptive immune responses

What is the function of T cells?

Drive cell-mediated immunity

What is the function of B cells?

Produce antibodies and drive humoral immunity

What is meant by humoral?

Anything produced by cells i.e. antibodies

What are the three main receptors involved in adaptive immunity?

-t cell receptors (TCR) -B cell receptor (Immunoglobulins[Ig]) -Major histocompatibility complex (MHC proteins)

Where are T cells derived from and where do they mature?

Bone marrow and thymus

What do all T cells start as?

Naïve T cells

What does the variable region of t cell receptors contain?

Antigen binding site

What are the genes rearranged by in T cell receptors?

Somatic recombination

What is somatic recombination driven by?

RAG (Recombinase) enzymes

Why is thymic education important?

To stop T cells responding to peptides in own body

Where are the T cell receptors arranged?

Thymus

What is positive selection of the T cell?

No recognition= apoptosis (cell destroyed)

What is negative T cell selection?

Recognition of self antigen= apoptosis

What do T cells interact with in the thymus?

Thymic cortical epithelial cells

Explain the three signals required to activate T cells

Function of TH1 cells?

Support macrophage function, by making lots of interferon-gamma

Main function of TH2 cells?

Produces lots of interleukin-4, 5 and 6 which instruct B cells to produced antibodies

Main function of TH17 cells?

Produce interleukin 17 and 22 which enhances clearance of extracellular bacteria and fungi

Function of T follicular helper cells?

Work with B cells for antibody production

What is the main function of Treg cells?

Release inhibitory cytokines ( interleukin 10) Inhibit T cell activation and dendritic cell activation

What are CD8+ cells driven by?

MHC 1 molecule, found on all cell types

What enzymes do cytotoxic T cells produce?

Granzyme and perforin

What is the function of perforin?

Facilitate granzyme entry into infected cell, once in cell causes apoptosis

What are the five different type of immunoglobins produced by B cells?

IgG IgE IgD IgM IgA

Functions of the five classes of immunoglobins!!!!

How many subsets does IgG have?

What is the difference between T cell and B cell receptor structure?

T cell have alpha and beta chains B cell receptors have heavy and light chains

Where do B cells develop?

Bone marrow

What do the heavy chains involve in B cell receptors?

Rearrangement of Variable (V), Diversity (D) and Joining (J) genes

What do the light chains involve in B cell receptors?

Rearrangement of Variable (V) and Joining (J) genes

What is the main immature B cell receptor?

IgM

What immunoglobins do mature B cells express on the surface?

IgM and IgD

Where do B cells undergo negative selection?

Bone marrow

What will happen to self reacting B cells?

Macrophages engulf any self-reacting B cells

What are the three main functions of antibodies?

Neutralization Opsonization Initiation of complement

What is opsonisation?

The coating of pathogens by antibodies or complement proteins -phagocytosis -Antibody dependant cellular cytotoxicity (ADCC) -Mast cell degranulation

What are the 2 B cell receptors?

IgD and IgM

Until when are B cells still known as naive?

Until they come in contact with an antigen

What two ways can B cells be activated?

Involving T cells- Thymus-dependant antigens Thymus-independent antigens

What does the activation of naïve B cells result in?

The rise of plasma cells

What are plasma cells?

Antibody factories

What is the first cells produced when a naïve B cell reacts with an antigen?

IgM

What is the affinity for an antigen?

The strength of a binding to an antigen

What is meant by the avidity of an antibody?

Ability of antibodies to form complexes