L1 - Structure and Components of the Immune System Flashcards by Asheton Mcinerney

Give 5 characteristics of the innate immune system

Rapid response, preformed, encoded in genome, no memory, not responsive to changes in pathogens

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Give 5 characteristics of the adaptive immune system

Slow initial response, rapid when pre-formed, not inherited, requires gene rearrangement of multiple segments, clonal, specific, has memory, not expressed by all cells of the same type

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What 3 types of barriers are there in the innate immune system? Give an example for each

Mechanical - skin, mucosa, cilia, mucus, coughs/sneezes
Chemical or biochemical - enzymes e.g. lysozyme, acids e.g. HCl in stomach
Microbiological - normal flora

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How can pathogens cross the body’s barriers?

Penetrate intact barriers or enter through damage

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What are the cellular components of the innate immune system?

Phagocytes (neutrophils, macrophages), granulocytes (mast cells, basophils, eosinophils), dendritic cells, natural-killer cells

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What immune system are the body’s barriers a part of?

The innate immune system

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What immune system is the compliment system a part of?

The innate immune system

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What is the role of phagocytic cells?

Recognise, engulf and kill pathogens

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What are the types of phagocytic cells?

Neutrophils and macrophages/monocytes

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What is the difference between a monocyte and a macrophage?

A monocyte is an immature macrophage in circulation; it matures into a macrophage when it enters tissues

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Which phagocyte acts as the first line of defence?

Neutrophil

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Which phagocyte acts as a sentinel cell?

Macrophage

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What immune cell is know for being multi-functional? Give 3 of its functions

Macrophage - phagocyte, sentinel cell, antigen presenting cell, ‘garbage collector’ (endogenous debris)

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Which phagocyte has pro- and anti-inflammatory properties? What are these properties?

Macrophage - releases cytokines and chemokines

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What are the roles of cytokines?

Cell-to-cell communication, inflammatory mediator

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What is the role of chemokines?

What are the 3 main chemokines released from sentinel cells?

Attract other cells to the site of inflammation

TNF-alpha, IL1 and IL6

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What are the names of the granulocytes?

Neutrophils (phagocyte), basophils, eosinophils, mast cells

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What is the role of the majority of granulocytes?

Release inflammatory mediators from granules

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Name some of the inflammatory mediators produced by granulocytes

Histamine, prostaglandin

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What do eosinophils produce, in addition to inflammatory mediators, that the other granulocytes don’t?

What is this useful for?

Lytic mediators - useful in defence against helminths

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What is the role of dendritic cells?

Antigen presenting cell

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What are the antigen presenting cells?

Macrophages, dendritic cells, B cells

What are the sentinel cells?

Macrophages, dendritic cells, mast cells

What is the only lymphocyte that is a part of the innate immune system?

Natural-killer cell

What do natural-killer cell cells target?

Cells that pose a threat to the body - malignancies or those infected with intracellular pathogens

How do natural-killer cells carry out their function?

Secrete cytotoxic proteins from granules onto target cells to trigger apoptosis

What is the role of complement proteins, and how do they do this?

They enhance the ability of antibodies and phagocytes to clear away pathogens by forming a complex on the pathogen surface, and creating a hole that immune cells can pass through

What are pathogen associated molecular patterns (PAMPs)?

Exogenous signals produced by microbial invaders

What are damage associated molecular patterns (DAMPs)?

Endogenous signals produced by damaged or dying cells

Give an example of a PAMP

Lipopolysaccharide (G-ve bacteria), viral genetic material, mannose, sialic acid

What recognises PAMPs and DAMPs?

Pattern recognition receptors on sentinel cells (macrophages, mast cells, dendritic cells)

What do pattern recognition receptors (PRRs) do? Give and example of a PRR

They recognise PAMPs and DAMPs (repeated patterns) and activate the innate immune system Toll-like receptors (TLR), rig1-like receptor (RLR), NOD-like receptor (NLR) C-type lectin receptor (CLR)

What are the 2 main groups of pathogen killing mechanisms employed by phagocytes?

Oxygen dependent and oxygen independent

What are some oxygen dependent pathogen killing mechanisms employed by phagocytes?

Anti-microbial oxygen-containing molecules, hydrogen peroxide, hypochlorite (bleach)

What are some oxygen independent pathogen killing mechanisms employed by phagocytes?

Nitric oxide, enzymes, anti-microbial peptides, act as competitors for resources to deprive pathogen

What are acute phase proteins?

They act as soluble pattern recognition molecules and enhance pathogen uptake by phagocytes

Name an acute phase protein

C-reactive protein, mannose-binding lectin, serum amyloid P

What are acute phase proteins produced in response to?

Pro-inflammatory cytokines e.g. IL1 and IL6

What cells are involved in the adaptive immune response?

B cells and T cells

Where do T and B cells get their names?

T cells - mature in thymus | B cells - mature in bone marrow, discovered in chicken bursa

What immune response do B cells make up? What does this response do?

Humoral immune response - uses antibodies to attack extracellular invaders

What immune response do T cells make up? What does this response do?

Cell-mediated immune response - cells coordinate attack on intracellular invaders

What are the main types of B cell?

B cells - plasma cell, memory B cell

What are the main types of T cell?

T cells - helper T cell, cytotoxic T cell, regulatory T cell, memory T cell

What are plasma cells? What is their role?

They are the effector cells of the humoral immune response that differentiate from B cells They produce soluble antibodies

What is the role of helper T cells (Th)?

Direct the immune response by producing cytokines

What is the role of cytotoxic T cells (Tc)?

Trigger infected cell apoptosis

What is the role of regulatory T cells (Treg)?

Supress immune response to keep it under control

What are the 2 forms of antibodies? What cells give rise to these?

B cell - produce transmembrane antibodies that act as receptors Plasma cell - produce soluble antibodies

What are the names of the two antibody domains?

``` Fragment antigen binding (fab) domain Fragment crystallisable (fc) domain ```

What is the role of the antibody fragment antigen binding (Fab) domain?

Binds antigens

What is the role of the antibody fragment crystallisable (Fc) domain?

Activates complement and phagocytes

What is clonal selection?

The mechanism through which B and T cells specific for an antigen are selected for proliferation

What steps are involved in clonal selection?

1. Antigen encounters B/T cells 2. Antigen binds a receptor that fits 3. The bound cell is sent a signal to proliferate 4. Cells differentiate into effector cells or memory cells