Immunology Flashcards by Esika Peter

What are the physical barriers to infection

Skin
Mucosa

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What are the mucosal barriers to infection

Respiratory tract (with cilia)
Gastrointestinal tract
Genital tract and urinary system

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What are the chemical barriers to infection

Hydrochloric acid (stomach)
Lysozyme (sweat and tears)

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Response duration of innate immune system

Rapid (0-4 hours)

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Innate immune system involves

Neutrophil
Basophil
Mast cell
Eosinophil
Monocyte
Macrophage
Natural Killer Cell
Dendritic Cell

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Function of neutrophil

Primary phagocytic cell in acute inflammation

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Neutrophile circulate through the _________________, they migrate to ______________

Blood and lymphatic system
Areas of inflammation

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Function of Eosinophil

Important in responding to parasites

Exocytosis of their granules

Phagocytosis (but less than neutrophils and macrophages)

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Eosinophils contain granules with…

Proinflammatory cytokines

Chemicals toxic to pathogens, such as “major basic protein“

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Function of basophil and mast cells

Allergic response

Contain cytoplasmic granules
Degranulation releases pro-inflammatory cytokines

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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)

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Pathogen associated molecular pattern (PAMPs) released by ________________ and attracts ____________

Foreign cells
Leukocytes

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Innate immune system are responsible for ________

Acute inflammation and killing of pathogen

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Response duration of adaptive immune response

Slow response (4-96 hours)

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Adaptive immune response involves

Helper T cell (CD4)
Cytotoxic T cell (CD8)
B cell
Plasma cell

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Function of Helper T cell (cell mediated response)

Recognise MHC II antigens

Mediates acute and chronic organ rejection

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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

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CD4 cells have _____________ receptors while CD8 cells have _______________ receptors

MHC Class II

MHC Class I

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Function of B cell (humoral response)

Mediates hyperacute organ rejection

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Function of Plasma cell

Produce large amounts of antibodies specific to particular antigen

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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

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B- cells differentiate in ______________

Germinal centre of lymph nodes, the spleen and MALT

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B cells mature in the _______________ while T cells mature in the _______________

Bone marrow
Thymus gland

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Natural Killer cells activated by….

Cytokines from macrophages and interferons

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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

Immunology Flashcards

(89 cards)