Immunology Flashcards
What are identifying features of innate immunity
Non-specific
Fast process with short lasting effect
Present from birth
Instinctive
What are some features of adaptive immunity
Slow process but long-lasting effects
Acquired
Requires lymphocytes
Specific
Antibodies
Name the 3 main polymorphonuclear leukocytes of the immune system
Neutrophil
Eosinophil
Basophil
What are the 3 main mononuclear leukocytes
Monocytes (differentiate to macrophages)
T-cells
B-cells (differentiate to plasma cells)
Function of neutrophils
phagocytic and bactericidal
Function of macrophages
Phagocytosis
Antigen presentation
Secretes cytokines
What type of infections are eosinophils important in
parasitic
Function of mast cells
Important in parasitic infection and allergic reactions
Main source of histamine
What are the 3 ‘professional’ APCs
Macrophages
B-cells
Dendritic cells
What is the most potent APC
dendritic cells
Where are macrophages derived from
Either derived from circulating blood monocytes or as tissue resident macrophages
What are complement proteins
Group of around 20 serum proteins secreted by the liver that needs to be activated to be functional
What are the 3 main outcomes of complement system activation
Direct lysis - C5 - C9
Attract more leukocytes to site of infection - C3a & C5a
Coat invading organism - C3b
What are the 5 distinct classes of immunoglobulin
IgG
IgA
IgM
IgE
IgD
What region on an antibody binds to receptors
Fc region
What region of an antibody binds with epitopes of antigens
Fab region
What does the constant region of an antibody determine
Determines antibody types and therefore effector function
Function of interferons
Induce a state of antiviral resistance in uninfected cells
Function of interleukins
Can cause cells to divide, differentiate and secrete factors
State the funtion of IL1 and IL10
IL-1: pro inflammatory
IL-10: anti-inflammatory
What is the most important interleukin in neutrophil production and recruitment
IL-8
Function of chemokines
Leukocyte chemoattractant
What is the function of colony stimulating factor
Involved in directing the division and differentiation of bone marrow stem cells
What are pattern recognition receptors
Encoded receptors that detect pathogen associated molecular patterns (PAMP) and damage associated molecular patterns (DAMPs)
What is T cell selection
When T cells that recognise self are killed in the foetal thymus as they mature
Importance of T cell receptor (TCR)
Recognises foreign antigens in association with major histocompatibility complex (MHC)
What is the function of T helper 2 (CD4)
Stimulates B cells to produce antibodies against extracellular pathogens. Secretes cytokines to help directly kill
What is the function of Cytotoxic T cells (CD8)
It helps the immune response against intracellular pathogens (e.g., viruses). Kills infected cells by binding to antigens and inducing apoptosis
Which cells express MHC1
All nucleated cells
Which cells express MHC2
Only antigen presenting cells
Which type of T cell binds to MCH1
CD8
Which type of T cell binds to MHC2
CD4
What is the function of T helper 1 (CD4)
Helps the immune response against intracellular pathogens. Activates macrophages, cytotoxic T cells and NK cells (cell mediated immunity)
What 2 substances are released by Tc to kill cells
Perforin and granzymes
How many antibodies can each B cell make
Each B cell can only make 1 Ab that will only bind to 1 epitope on one antigen
Where are B cells that recognise ‘self’ killed
bone marrow
Describe how T helper cells bind to B cells
- An antibody binds to an antigen
- phagocytosis
- epitope is displayed on surface of the B-cell bound to an MHC2
- TH2 binds to MHC2 on B cell
- Cytokine secretion induces B-cell clonal expansion
- Differentiation into plasma and memory B cells
Give 3 function of antibodies
- Neutralise toxins.
- Opsonisation.
- Activate classical complement system
Name 4 types of cytokines
- Interferons.
- Interleukins.
- Colony stimulating factors.
- Tumour necrosis factors.
What is the function of tumour necrosis factor
Mediates inflammation and cytotoxic reactions
Give examples of secondary lymphoid tissue
Spleen
Lymph nodes
Mucosa association lymphoid tissue
What initiates the classical complement pathway?
Antigen-antibody complexes bind complement and activate the cascade
What activates the alternative pathway?
Bacterial cell walls and endotoxin (pathogen surfaces)
What activates the lectin pathway?
Mannose binding lectin
What are the 3 different pathways that make up the complement system?
- Classical.
- Lectin.
- Alternative.
Main function of toll-like receptors (TLRs)
TLR’s send signals to the nucleus to secrete cytokines and interferons. These signals initiate tissue repair. Enhanced TLR signalling = improved immune response.
What happens when a PAMP binds to a PRR
The innate immune response and inflammatory response is triggered
Describe the process of extravasation.
- Macrophages at tissues release TNF alpha.
- The endothelium is stimulated to express adhesion molecules and to stimulate chemokines.
- Neutrophils bind to adhesion molecules; they roll, slow down and become stuck to the endothelium.
- Neutrophils are activated by chemokines.
- Neutrophils pass through the endothelium to the tissue to help fight infection.
What is an allergy?
An abnormal response to harmless foreign material.
What is atopy
The tendency to develop allergies.
Which Ig is most commonly involved in allergic responses?
IgE
Which cells express high affinity IgE receptors?
Mast cells, basophils and eosinophils.
What is the main IgE receptor cell
Mast cells
Describe type 1 hypersensitivity
IgE mediated
Prior exposure to antigen/ drug
IgE becomes attached to mast cells and re-exposure causes mast cell degranulation and release of histamine
Give example of symptoms of anaphylaxis
Vasodilation
Shortness of breath
Itchy skin
Vomiting
Describe type 2 hypersensitivity (cell bound)
IgM or IgG bind to self-antigen leading to cell destruction
Give 3 functions of antibodies
neutralise toxins
Opsonisation
Activate classical complement system
Give 3 conditions that basophils are important in
Asthma
Anaphylaxis
Hay fever
Function of basophils
Release histamine
Secrete serotonin and heparin
Describe type 3 hypersensitivity
IgG binds soluble antigens forming a circulating immune complex. These deposit in vesel walls which gives rise to an inflammatory response
Describe type 4 hypersensitivity
T cell mediated
What is the B cell maturation site
Bone marrow
Function of TLR2
Detects lipoteichoic acid derived of G+ve bacteria
Function of TLR4
Detects lipopolysaccharide (LPS) of G-ve bacteria
What does TLR5 detect
Flagellin
Function of regulatory T cells (Tregs)
Suppress immune response to maintain immune response and self-tolerance
What is the most important cytokine in neutrophil production and recruitment
IL-8
Describe how T helper cells bind to B cells
- An antibody binds to an antigen
- Phagocytosis
- Epitope is displayed on surface of the B-cell bound to an MHC2
- TH2 binds to MHC2 on B cell
- Cytokine secretion induces B-cell clonal expansion
- Differentiation into plasma and memory B cells
On which proteins are MHC proteins found on?
Chromosome 6
Treatment for anaphylaxis
IM adrenaline
Antihistamines can be used after this (chlorphenamine and hydrocortisone)
What cytokine is responsible for activating macrophages
Interferon gamma
Function of IL-4
Key cytokine for allergic inflammation
Induces IgE production
Promotes Th2 differentiation
Which antibody is responsible for secondary responses to a previous infection
IgG - Has a higher affinity for antigens than other antibodies
Which Ig is found in breast milk and other secretions
IgA - protects mucosal surfaces
What are all complement pathways cleaved to
active C3 convertase
