Immunology Flashcards
What are the physical barriers to infection
Skin
Mucosa
What are the mucosal barriers to infection
Respiratory tract (with cilia)
Gastrointestinal tract
Genital tract and urinary system
What are the chemical barriers to infection
Hydrochloric acid (stomach)
Lysozyme (sweat and tears)
Response duration of innate immune system
Rapid (0-4 hours)
Innate immune system involves
Neutrophil
Basophil
Mast cell
Eosinophil
Monocyte
Macrophage
Natural Killer Cell
Dendritic Cell
Function of neutrophil
Primary phagocytic cell in acute inflammation
Neutrophile circulate through the _________________, they migrate to ______________
Blood and lymphatic system
Areas of inflammation
Function of Eosinophil
Important in responding to parasites
Exocytosis of their granules
Phagocytosis (but less than neutrophils and macrophages)
Eosinophils contain granules with…
Proinflammatory cytokines
Chemicals toxic to pathogens, such as “major basic protein“
Function of basophil and mast cells
Allergic response
- Contain cytoplasmic granules
- Degranulation releases pro-inflammatory cytokines
Function of macrophages
Recognise “Pathogen-associated molecular patterns” (PAMPs)
Kill pathogens and abnormal cells by phagocytosis
Release cytokines that initiate the inflammatory response
Activate the other cells of the immune system (e.g. interferons)
Pathogen associated molecular pattern (PAMPs) released by ________________ and attracts ____________
Foreign cells
Leukocytes
Innate immune system are responsible for ________
Acute inflammation and killing of pathogen
Response duration of adaptive immune response
Slow response (4-96 hours)
Adaptive immune response involves
Helper T cell (CD4)
Cytotoxic T cell (CD8)
B cell
Plasma cell
Function of Helper T cell (cell mediated response)
Recognise MHC II antigens
Mediates acute and chronic organ rejection
Function Cytotoxic T cell (cell mediated response)
Granule exocytosis causing destruction of the cell
Induces apoptosis in virally infected and tumour cells via activating the Fas pathway
Recognise MHC I antigens
Mediates acute and chronic organ rejection
CD4 cells have _____________ receptors while CD8 cells have _______________ receptors
MHC Class II
MHC Class I
Function of B cell (humoral response)
Mediates hyperacute organ rejection
Function of Plasma cell
Produce large amounts of antibodies specific to particular antigen
Once activated B-cells can become either…
Plasma cell – secrete antibodies (also called immunoglobulins)
Memory B cell – await a later infection with the same pathogen
B- cells differentiate in ______________
Germinal centre of lymph nodes, the spleen and MALT
B cells mature in the _______________ while T cells mature in the _______________
Bone marrow
Thymus gland
Natural Killer cells activated by….
Cytokines from macrophages and interferons
Function of Natural Killer Cells
Recognise virally infected or abnormal (e.g. cancerous) cells
Destroy these cells by releasing cytokines that stimulate apoptosis in cell or create a hole in the cell membrane causing lysis
Release IFN-γ that activates macrophages
Specialist dendritic cells found in the skin are called ________________
Langerhans cells
Function of Dendritic cells
Take up antigens, process them and display them on their cell surface
Have both MHC class I and class II molecules
Act as messengers, taking antigens from infected tissues to lymph nodes to activate T cells
Antibody types released from Plasma cells….
IgA (commonest)
IgE
Antibody types released from Mature B cells….
IgG (commonest in blood serum)
IgD
Antibody types released from short lived plasma cells….
IgM (first infection response)
Function of IgA
Neutralisation (serum)
Neonatal protection
Mucosal neutralisation (secretory)
Protect mucosa from infection
Function of IgG
Foetal protection
Opsonisation
Neutralisation
Agglutination system activation
NKC activation
Function of IgE
Allergic response (mast cells, eosinophils, basophils)
The outer area of the thymus is called the ________, which is where T cells ______________________
Cortex
Proliferate and start develop into specialised cells
The inner area of the thymus is called the ______________, which is where the mature T cells are found __________________________.
Medulla
Before they enter the blood, and it also contains the waste products of defective T cells
Role of lymph nodes….
Hold lots of cells of the immune system, particularly lymphocytes
Act as filters for pathogens and abnormal cells
What does follicles of lymph nodes contain
Primary follicles contain unstimulated B cells and do not have germinal centres
Secondary follicles have germinal centres (that stain a lighter colour) and contain activated B cell that are generating plasma cells and memory B cells
What does cortex, paracortex and medulla of lymph node contain
Cortex – contains B cells and follicles
Paracortex – contains T cells and dendritic cells
Medulla – contains plasma cells, T and B cells and macrophages
Red pulp is where _____________________
Old red blood cells are removed
Immune cells wrap themselves around the arterioles in the spleen forming the _______________
White pulp
Immediately around the arteriole in the spleen is the ___________________________
Peri-arteriolar lymphoid sheath (PALS)
Peri-arteriolar lymphoid sheath (PALS) contain…..
T cells and dendritic cells
The __________________ surrounds the PALS in the white pulp of the spleen
Marginal zone
Marginal zone contains……
B cells and macrophages
__________________________ are various substances that are unique to pathogens, such as double stranded RNA, unmethylated DNA (from bacteria), mannose-containing carbohydrates (from bacteria) and lipopolysaccharide (from bacteria cell walls)
Pathogen-Associated Molecular Patterns (PAMPs)
_____________________ are the receptors on cells of the innate immune system (most notably macrophages) that allow them to recognise PAMPs
Toll Like Receptors (TLRs)
Opsonins are any molecule that ______________________________
Binds to a pathogen or pathogenic material and signals to phagocytes to destroy that pathogen by phagocytosis
Macrophages have _____________________ that allow them to recognise features that are generic to pathogens, called __________________________________
Toll-Like Receptors (TLRs)
Pathogen-associated molecular patterns (PAMPs)
Why are TLRs and PAMPs recognised as a foreign invader to the body?
As they are not present on human cells
Phagocytosis is the process of ___________________________
Recognising pathogens or abnormal or infected cells, ingesting them and killing them
Cells responsible for phagocytosis
Macrophages
Neutrophils
Eosinophils
4 stages of phagocytosis
Attachment
Ingestion
Killing
Degradation
Inflammation helps the innate immune system by…
Activates more macrophages
Recruiting monocytes that differentiate into macrophages when they enter the tissue
Recruits and activates neutrophils and NK cells
Brings opsonins that help macrophages and neutrophils recognise and phagocytose pathogens
Interferons are cytokines that are produced by….
Macrophages
Lymphocytes (particularly natural killer cells)
Endothelial
Epithelial cells
Inteferons act by….
Blocking viral entry into cells
Block viral replication inside cells
Activate macrophages and natural killer cells
Localised effects of inflammation on local tissues
Activation of endothelial cells to display adhesion molecules
Vasodilation
Increased vascular permeability
Inflammation leads to activation of pro-inflammatory systems such as
Clotting
Kinin
Complement
Cytokine that simulates the liver to produce acute phase proteins (opsonins)
IL-6
Cytokine that act on the central nervous system to cause fever, lethargy and anorexia
IL-1
Cytokine that recruits and activates neutrophils
IL-8
Cytokines that activate natural killer cells
IL-2 and IL-12
T or F: Tumour necrosis factor alpha (TNF-α) has the same action of all of the other interleukins
True
Class I MHC molecules are found on ______________________ while Class II MHC molecules are found on __________________________
Almost all cells with a nucleus
Mostly dendritic cells, macrophages, monocytes and B cells
Class I MHC molecules present _________________________ while Class II MHC molecules present _________________________
Antigens that come from within the cells (i.e. from a virus that had infected and is replicating within the cell)
Antigens that come from outside the cell
Class I MHC molecules recognised exclusively by _______________ while Class II MHC molecules recognised exclusively by ________________
CD8 cells
CD4 cells
Th1 are stimulate B cells to produce _____________ while Th2 stimulate B cells to produce _________________
IgG
All antibodies but especially IgE
Th1 cells are responsible for….
Delayed-type (Type IV) hypersensitivity reactions
Th 1 secrete ___________ which stimulates the proliferation and differentiation of other ______________
IL-2
CD4 and CD8 cells
Th 2 cells are responsible for….
Type 1 hypersensitivity reactions (allergy) and asthma
Parasitic infections
IgA secreted in
Saliva, respiratory secretions and breast milk
________is the most common antibody in the blood
IgG
_________is the first antibody produced in an acute infection
IgM
T cells recognise antigens using a specific type of receptor called the….
T-cell Receptor (TcR)
T or F: T cells can recognise free floating antigens
False
T cells require the antigen to be presented to them by ________________________ on the surface of other cells
Major histocompatibility complex molecules
Major histocompatibility complex is also known as….
Human Leukocyte Antigen (HLA)
How are CD4 cells activated
Dendritic cells recognise pathogenic material, absorb it and present it on their Class II MHC molecules
Once activated, dendritic cells leave the tissues, enter the blood and travel to the lymphatic tissue
They enter the paracortex in lymph nodes or the PALS in the spleen and search for the relevant CD4 cells that matches the antigen they are displaying
Dendritic cells also wait in these areas for free floating antigens that they can pick up and display for CD4 cells
Dendritic cells pick up antigenic material, display it on _______________ and travel to _________________, this is recognised by CD8 cells that have __________________. These cells then undergo dramatic proliferation and differentiation into ___________________
MHC class I molecules (as well as class II)
Lymphatic tissue
TcRs specific to that antigen
Cytotoxic T cells specific to that antigen
Mechanisms by which cytotoxic T cells destroy infected cells
Granule exocytosis
By activating the Fas molecule
“Granule exocytosis”, where they spray the infected cell with enzymes that ________________ and cause ___________________
Destroy the membrane
Cell lysis and death
Fas molecule undergoes _________ once activated
Apoptosis
IgE is important in ___________, and measuring specific IgE to allergens (e.g. peanuts) can give an indication about _______________
Asthma and allergy
Person’s allergy status
Measuring IgG is useful to ___________________
Detect a patients immunity to a condition (e.g. response to a vaccine or having previously had a condition such as chickenpox)
Measuring IgM gives a good indication of an ________, as it tends to ______________
Acute infection
Disappear once the infection is gone (unlike IgG)
IgM has a ________ in the blood
Snowflake appearance
The formation of memory B cells accounts for the ___________________ after vaccination
Rapid production of IgG at re-exposure to a microbe
_______________ only contain specific parts of the organism (such as the exact antigen required) to stimulate an immune response and the subsequent immunity to the disease
Subunit vaccines
_________________ contain pathogens that have been treated to kill them (e.g. with heat) to make them unable to cause an infection but still contain all the necessary antigens to stimulate an immune response
Inactivated vaccines
________________ contain a weakened version of the virus, and are still capable of causing the infection and should be avoided in immunosuppressed patients
Live attenuated vaccines
