Immunology Flashcards
Cells that are in the innate immune system
Mast cells, macrophages, NK cells, Neutrophils, Complement
With regards to immune deficiency, what does SPUR refer to?
S - serious infectionsP - Persistent infectionsU - Unusual infectionsR - Recurrent Infections
Features that may indicate a primary immune deficiency (6)
Weight loss/Failure to thriveSevere skin rashesChronic diarrhoeaMouth UlcerationUnusual Autoimmune DiseaseFamily History
The main difference between primary and secondary immune deficiencies is…
that primary only tends to involve one component of the immune system, secondary tends to involve multiple
Examples of Secondary Immune Deficiencies
HIV, Malignancy, nutrition disorder, infection, treatment interventions
Cells in the Innate Immune system (4)
MacrophagesNeutrophilsMast cellsNK cells
Phagocytes of the innate immune system (2)
Macrophagesneutrophils
Proteins of the innate immune system (3)
ComplementCytokinesAcute Phase Proteins
What does the innate immune system stimulate?
Rapid clearance of micro-organismsAcquired Immune response
What does the innate immune system recognise in infectious organisms?
PAMPs
Cells of Acquired Immune Response (2)
B LymphocytesT lymphocytes
Proteins of acquired immune response (1)
Antibodies
Which immune system is NOT genetically encoded?
Acquired
Functions of Phagocytes (5)
Initiation and amplification of inflammatory responseScavenging of cellular and infectious debrisIngest and kill micro-organismsResolution and repairProduce inflammatory molecules regulating immune system
TRUE OR FALSE - phagocytes are particularly important in the defence against viruses and bacteria
FALSE - they are important in the defence against bacteria and fungi
In phagocyte deficiencies it is not uncommon to see the following infections…
Common - staph. aureusUnusual - burkholderia cepaciaMycobacteriaFungi - candida, aspergillus
TRUE OR FALSE - phagocytes are important in reducing the numbers of infections as can be seen in stem cell transplant recipients
TRUE
Reticular Dysgenesis is characterised by an absence of _____ and other myeloid cells with almost complete deficiency of _______ in peripheral blood.
neutrophils, lymphocytes
In reticular dysgenesis, a lack of both innate and adaptive immune response is due to a failure of ______ ______ differentiating along a ______ lineage
stem cells, myeloid
Kostmann syndrome is a rare autosomal ______ disorder
recessive
Kostmann syndrome is a severe, chronic _____ where normal levels of ______ are >3000µL and in sufferers is <200µL
neutropenia, neutrophils
G-CSF is
granulocyte colony stimulating factor which assist the maturation of neutrophils
In a condition where issues arise in the ability to bind endothelial adhesion markers, you may see…
increased levels of neutrophils with recurrent bacterial and fungal infections.There can be deep infections with no pus formation
Why does a loss of function of a receptor or antigen recognition marker not cause severe disease?
there is usually other receptors or antigens which can be picked up
Example of a disease where there is failure of oxidative killing mechanisms
Chronic Granulomatous disease
consequences of chronic granulomatous disease
failure to degrade chemoattractants and antigens as well as disease –> accumulation of neutrophils, macrophages and lymphocytes
Test for chronic granulomatous disease?
Nitroblue tetrazolium test –> looking for release of H2O2
Describe the IL-12 –> IFNy network
infected macrophages produce IL-12IL-12 induces Th1 cells to secrete IFNyIFNy feeds back to macrophages and neutrophils Leads to production of TNF –> NADPH oxidaseOxidative pathways
Defects in IL-12:IFNy network may increase susceptibility to…
mycobacterial infections and IC bacteria
Where do T lymphocytes arise from?
haematopoetic stem cells
TRUE or FALSE - T lymphocytes defend against intracellular pathogens and bacteria
FALSE - against intracellular pathogens and viruses
The CD4+ T Lymphocyte has immunoregulatory functions - give some examples (3)
Provides co-stimulatory signals for CD8 and B lymphocytesProduces cytokinesRegulates other lymphocytes and phagocytes
The CD4+ lymphocyte recognises peptides present on HLA class __ molecules?
II - 2
CD8+ lymphocytes recognise peptides present on HLA class __ molecules?
I - 1
CD8+ lymphocytes are specialised killer cells…give examples (3)
Production of pore-forming molecules - perforintriggering of apoptosis of targetsecretion of cytokines i.e. IFNy
Where are mature B lymphocytes typically found? (3)
bone marrow, lymphoid tissue, spleen
When a B lymphocyte is activated, what happens?
Undergoes complex genetic rearrangement, forms memory cells and plasma cells
Function of antibodies (3)
Identification of pathogensRecruitment of other immune system components for pathogen removalNeutralisation of toxins
X-Linked SCID is involved with a mutation in which cytokine receptor?
IL-2
What is IL-2 involved in?
ability to respond to other cytokinesT cell and NK developmentproduction of B cells
Is it advisable to give vaccines to X-linked SCID patients?
No - there is a defect in acquired immune response so could actually produce more problems than solutions
DiGeorge patients suffer from immune deficiencies, which organ fails to develop sufficiently?
thymus
What level of B cells would you expect in a DiGeorge patient?
Normal or increased B cells
What sort of recurrent infections would you expect to see in B cell deficiencies?
Bacterial Resp. tract, GI
What does common variable Immune deficiency indicate?
low levels of IgG, IgA, IgE recurrent bacterial infectionsautoimmune diseases
T cells mature in the ______ gland
thymus
Which cells provide immunity to extracellular bacteria, fungi and parasites?
neutrophils, macrophages, complement system, antibodies, cytotoxic T cells, NK cells
Where are basophils and eosinophils found?
circulating the blood
Th2 cells contribute to which hypersensitivity reaction?
Type 1 Hypersensitivity
T helper cells recognise which MHC class
Class II
What is the lymphatic system?
a system of vessels draining fluid from body tissues with lymph nodes positioned regularly to trap pathogens
What are the kupffer cells?
macrophages in the liver
Most abundant immunoglobulin
IgG
Common antibodies involved in Type II hypersensitivity
IgG and IgM
B cells differentiate into _____ cells
plasma cells
Type III hypersensitivity reactions result in the accumulation of which cell types?
neutrophils, macrophages
What is the complement system?
a family of approx. 30 proteins produced in the liver and circulating the blood as inactive precursors
B cells mature in the ____ _____
bone marrow
What is an antigen?
any substance which can stimulate an adaptive immune response i.e. lipids, proteins, carbohydrates
where are monocytes found?
circulating the blood - move into peripheral tissues and differentiate into macrophages
CD4 cells differentiate into what upon activation?
Th1 and TH2 cells
What is the function of CRP?
Opsonisation
What are antibodies?
proteins that are produced in response to an antigen and bind specifically to that antigen
C3b activates the rest of the complement cascade which is…
C5 - C9
Ig which can cross the placenta?
IgG
What is the purpose of phagocytic cells?
they ingest and clear debris from the body including dead/dying apoptotic cells
Cytotoxic T cells recognise which MHC class
Class I
Where is the primary lymphoid tissue?
Bone marrow and thymus gland
Mesangial cells
macrophages in the kidney
What is the other name for neutrophils?
polymorphs
Th1 cells produce which cytokine?
Interferon
Immune complexes activate ______ ______ by the classical pathway
complement cascade
Alveolar macrophages
Macrophages in the lung
Most common location for IgA
Secretions and mucus
C3b can also act as what?
an opsonin
MHC Class II regulates NK cells - T/F?
False - NK cells are regulated by MHC Class I proteins which disappear if a cell is infected
What must occur for anaphylactic shock to initiate?
Systemic Type I response - rather than just at the point of entry
Where are mast cells found?
in tissues and mucosal surfaces exposed to the outside environment
Give some examples of secondary lymphoid tissue
spleen, lymph nodes, lymphatic system
CD4 cells are
T helper cells
Type III hypersensitivity reactions occur at the time of exposure - true or false?
false - around 4-8 hours after exposure
CD8 is expressed on…
Cytotoxic T cells
Classic C3 pathway for activation is initiated by?
Ig binding to antigen
Reactions are triggered by what sequence of events in Type II hypersensitivity?
Antibody binding to antigen on cell surface resulting in cell lysis and inflammatory response at the site
What are the key lymphocytes?
T CellsB CellsNK Cells
What role do mast cells, basophils and eosinophils have in the immune response?
protect against large pathogens which cannot be phagocytosedalso play a role in mediating allergic reactions
Interferon activates what cell type?
macrophages
What is the role of the dendritic cell in the secondary lymphoid tissue?
antigen presentation to T cells
Where do dendritic cells migrate once mature?
secondary lymphoid tissue
T cells defend against intracellular pathogens True/False?
True - they defend against intracellular pathogens such as viruses or mycobacteria
Type I hypersensitivity is mediated by what region of the immune system?
IgE on mast cells, Th2 cells
What are macrophages?
long-lived tissue resident phagocytes
Type II reactions are more common in what sort of conditions?
Autoimmune conditions
What are the key phagocytes?
NeutrophilsMonocytesMacrophagesDendritic cells
What is lymphoedema?
a condition of localised fluid retention and tissue swelling caused by a compromised lymphatic system
CD8 cells are
cytotoxic T cells
IL-4 and IL-13 result in the production of further…
IgE
Suggest a pro-inflammatory cytokine
TNFa (tumour necrosis factor alpha)
B cells defend against intracellular pathogens True/False?
False - they defend against extracellular pathogens
Cytotoxic T cells are particularly important in defence against?
Viruses and Fungi
What are NK cells?
large granular lymphocytes
Type IV hypersensitivity is mediated by what cell type?
T lymphocytes
What are the other cells of the immune system?
mast cells, eosinophils, basophils
Th2 cells produce which cytokines?
IL-4 and IL-5
C3a and C5a can act as what?
chemotaxins
Where can mature B and T cells be found?
circulating the blood, lymph and secondary lymphoid tissues
Special feature of IgM
first molecule to appear in immune response, produced by immature B cells
Largest immunoglobulin
IgM
What do NK cells target?
tumour cells, virally infected cells, antibody bound cells and pathogens
What are the subdivisions of T cells?
Helper T cellsCytotoxic T cells
IgE is found in
mast cells and basophils
Second most abundant immunoglobulin
IgA
The B cell receptor is composed mainly of monomeric Ig__
M
What is the role of cytokines in the immune response?
to modulate the behaviour of cells and thus co-ordinating the immune system
Examples of reactions experienced in patient of Type I hypersensitivity
Swollen and leaky mucosaContraction of smooth muscle - bronchospasmGlandular production of mucus Congestion
Examples of Type III hypersensitivity reactions
Farmers lung Pigeon Fanciers lungSystemic Lupus Erythematosus (SLE)
IgM is found in the ….
plasma
microglia
macrophages in the brain
T cells are responsible for
cell-mediated immunity
What do B cells transform into during an immune response?
plasma cells
What are the soluble factors of the immune response?
AntibodiesComplements system proteinsCytokinesAcute Phase proteins
Suggest an anti-viral cytokine
IFN (interferons)
Cytokines produced by phagocytes can have systemic as well as local effect. Give an example of a systemic effect
Production of CRP from liver cells
How long does Type IV hypersensitivity take to develop?
24-48 hours
Type I hypersensitivity leads to…
Asthma, allergies, hayfever and anaphylactic shock
Which cells provide immunity to Intracellular Bacteria and parasites?
Ab, Cytotoxic T cells, NK cells
Examples of a type II hypersensitivity reaction
Good Pasture SyndromeHaemolytic anemiaTransfusion reactions
What will happen upon prolonged exposure to antigen in Type IV hypersensitivity reactions?
progressive tissue damage and fibrosis
Which cells help provide immunity against Helminths?
eosinophils, mast cells, basophils and antibodies (thus also B cells)
What are the key features of the immune system?
Ability to identify self and non-self pathogensAbility to modify the response to different pathogensAbility to actively promote tissue repairAbility to remember the pathogens it encounters
What controls cell migration?
chemokines
What are the additional functions of macrophages?
limiting inflammation, tissue repair and wound healing and antigen presentation
What are cytokines?
small proteins and peptides that are produced in response to infection, inflammation and tissue damage
Which cells are highly granular?
mast cells, basophils and eosinophils
What is the secondary lymphoid tissue?
site where the adaptive immune responses are initiated
Normal pathway stimulated in people without Type I hypersensitivity on exposure to antigen?
IgG or IgA
phagocytic cells are an important source of cytokines - t/f?
true
What happens to the complement proteins when they enter an inflammed tissue?
become activate by enzymatic cleavage thus activating the complement cascade
Where are antibodies produced?
antigen activated B-cells
Type III hypersensitivity reactions are the result of deposition or formation of ______ _____ in situ
immune complexes
Type IV hypersensitivity reactions are also known as?
delayed hypersensitivity reactions
What do mast cells, basophils and eosinophils produce?
histamine, heparin, cytokines - all associated with acute inflammation
CD4 is expressed on…
Helper T cells
Which cells mediate cell-mediated immunity?
leukocytes
In Type I hypersensitivity reactions, Th2 cells produce which cytokines important to the response?
IL-4 and IL-13
What are dendritic cells?
immature cells present in the peripheral tissues and phagocytose antigens when they mature
How many signals are required for complete B cell activation?
2 - one from antigen binding, another from T cell binding or complement proteins
Type III hypersensitivity reactions may be local or generalised - true or false
true
Which parts of the immune system work as anti-virals?
Cytokines, Cytotoxic T cells, Antibodies, NK Cell
What are the two methods of activating an innate immune cells response?
- direct contact between receptors
- indirect contact with cytokines
Effects of the innate immune system on blood flow (4)
- dilation of small blood vessels
- Increased and slowed blood flow
- cell accumulation
- increased permeability
What do pathogens express which allow them to be identified?
Pathogen Associated Molecular Patterns (PAMPs)
3 phases of the innate immune system:
- Recognition
- Activation
- Effector
Identify the cell
Eosinophil
- Bilobar nucleus
- secretory vesicles ready to release toxins
Macrophages develop from what type of cell?
Monocytes
Innate immune cells identify PAMPs via…
Pattern-Recognition-Receptors PRRs
Where do macrophages reside?
Epithelial tissue i.e. lung, skin, gut
Four functions of macrophages
- ingest and kill EC pathogens
- regulate inflammatory responses
- promote tissue repair and wound healing
- antigen presentation
What type of cells are cleared by macrophages?
Apoptotic
The appearance of what molecule on the cell surface indicates that a cell is undergoing apoptosis and is ready to be engulfed?
Phosphatidyl serine
IL-10 serves what purpose in the immune system?
Acts as an anti-inflammatory cytokine
Where do mast cells reside?
tissues and mucosal surfaces
Mast cells are key in protecting against what type of pathogen?
Parasites
NK cells specifically kill infected cells and cancer cells which are no longer expressing what key molecule?
MHC Class I
Macrophages, Mast cells and NK cells all have the ability to produce what pro-inflammatory mediators?(8)
(you don’t need to know them all but be aware of the main ones in bold)
- NO
- Prostaglandins
- Histamine
- Leukotrienes
- Cytokines and Chemokines
- ROS
- Glycopeptides
- Anti-microbial peptides
