Immunology Flashcards
What is innate immunity?
Non-specific responses.
What is adaptive immunity?
Specific responses.
1st line of innate immunity.
Skin
Mucous membranes and secretions
2nd line of innate immunity.
Innate immune cells
Inflammation
Complement
3rd line of adaptive immunity.
T cells
B cells
(Lymphocytes)
Humoral response of adaptive immunity.
B lymphocytes
Effector cells:
Plasma cells and memory cells
Cellular response of adaptive immunity.
T lymphocytes
Effector cells:
T helper cells, memory cells and T cytotoxic cells
Differences between innate and adaptive immunity.
Innate:
Fast
Non-specific
No immune memory
Adaptive:
Slow
Specific
Immune memory
Which response is faster and stronger?
Secondary
Two types of acquired immunity
Naturally acquired immunity and artificially acquired immunity.
Two types of naturally acquired immunity.
Active- direct exposure to pathogens
Passive- maternal antibodies passed via the placenta
Two types of artificially acquired immunity.
Active vaccination
Passive- administration of immune serum
Where to T cell progenitor cells coriginate?
Bone marrow.
Where do T cell progenitor cells mature?
Thymus.
What is the order of maturation of lymphocytes?
T progenitor cell
Thymus
Mature T cells
Circulation
Peripheral lymphoid organs
Why do T cells have self tolerance unresponsiveness to self-antigens?
Prevent autoimmune reactions.
What is central tolerance?
Elimination of auto reactive immature T cells.
What is peripheral tolerance?
Elimination of auto reactive mature T cells.
What are T helper cells also referred to as?
CD4+ cells.
What are T cytotoxic cells as referred to as?
CD8+ cells.
Requirements for T cell activation
Antigen presented as peptides
APCs using MHC molecules
Co-stimulators on the APCs
Cytokines
What are co-stimulators?
Things that are required for T cell activation in addition to the antigen
Function of T helper cells
Co-ordinate the immune response
Types of T helper cells
Treg
Th1
Th2
Th17
What do native cell differentiate into?
Different types of T helper cells
What are T helper cells dependent on?
The type of cytokine secreted by the APC and other immune cells at the time
What do Treg cells do?
Regulate the immune response
Anti inflammatory
Inhibit M1 and promotes M2
Inhibit activation of neutrophils
Promotes angiogenesis
What are Th1 and Th17?
Pro-inflammatory
What do Th2 do?
Promote M2 polarisation
What are M1 macrophage?
Pro-inflammatory so cause tissue damage
What are M2 macrophages?
Anti-inflammatory so cause tissue repair
What what are 2 major types of MHC protein molecules?
Class 1 MHC molecules
Class 2 MHC molecules
Where are class 1 MHC molecules found?
On every nucleated cell in an organism
Where are class 2 MHC molecules found?
Macrophages, dendritic cells and B cells
What do MHC1 cells present peptides to?
T cytotoxic cells
What do MHC2 present peptides to?
T helper cells
What are the functions of cytotoxic T cells?
Kill target cells bearing specific antigen while sparing neighbouring uninflected cells
Properties of memory T cells
Specific for antigen
Persist for years
Respond more rapidly to specific antigen stimulation than naive cells
Express increased levels of anti-apoptotic proteins
What do B lymphocytes on activation differentiate into?
Plasma cells
What are antigen presenting cells?
B cells, macrophages and dendritic cells
What do blood cells originate from?
Hematopoietic cell
What is the role of antigen presenting cells?
To present antigens to the cells of the adaptive immune response
What does innate immune cells recognise antigens using?
Pathogen Recognition Receptors present on/in the cells
What do T cells arise from?
Lymphoid progenitor cells
Where do neutrophils arise from?
Myeloid progenitor cells
What do B lymphocytes leave the bone marrow as?
Immature cells
Where do B lymphocytes complete their development?
Peripheral lymphoid organ
Can an individual gain active acquired immunity from maternal antibodies?
No
What do vaccines with live/killed micro-organisms provide?
Active artificially acquired immunity
What does the lymph have a composition similar to?
Interstitial fluid
What body part in a component of the peripheral lymphoid organs?
Tonsils
What are naive T cells?
Mature cells that haven’t been exposed to antigens
How do T helper cells co-ordinate the immune response?
Activating macrophages
Helping in B cells activation
Secreting specific cytokines
What is required for a T cell to be required?
Antigen presented by APCs
Co-stimulators
Antigenic peptides presented on MHC molecules
What are the cells of the innate immune response responsible for antigen presentation?
Macrophages and dendritic cells
When does receptor editing occur?
During B cell tolerance
What is responsible for antigen recognition on B cells?
B cell receptors
Which immunoglobulin molecules is B-cell receptor composed of?
IgM and IgD
What is MHC independent?
B cell antigen recognition
Can B lymphocytes can recognise extracellular intact antigen?
Yes
What are epitopes in intact foreign material recognised by?
B cells
What are process protein peptides recognised by?
T cells
What is the immune response that targets intracellular pathogens?
Cellular
What is the immune response that targets extracellular pathogens?
Humoral
What can each B cell receptor bind to?
2 antigenic determinants
What can each T cell receptor bind to?
1 antigenic peptide
What is class switching?
The ability of an activated B cell to change the antibody isotope secreted
What is the general name for the inactive form on an enzyme?
Zymogen
What do complement proteins belong to?
Innate immune response
What do the complement proteins result in the formation of?
Membrane attack complex
What do complement proteins do?
Lyse pathogen infected cells
Act as opsonins
Encourage phagocytosis
What is the classical pathway initiated by?
The C1 protein of the complement pathway in response to antigens
What can complement protein bind to?
Antigens
Antigen-antibody complex
Mannose residues on pathogens
How many major pathways of complement activation are there?
3
What does obligate virus refer to?
A virus that requires a living host to replicate
What is a virus typically made of?
Protein coat and nucleic acid
What is the viral envelope primarily made of?
Lipid
What can the viral nucleic acid be structured as?
Single stranded
Double stranded
Linear
Circular
What is herpes simplex virus 1 described as?
Double stranded linear
What can viruses be classified by?
Genome structure
Type of mRNA
Viral hosts
What is the Baltimore Classification of viruses based on?
The mode of mRNA production
What are bacteriophages?
Viruses that infect bacteria
What is the natural host of T4 bacteriophage?
E.coli
What is a characteristic feature of the lysogenic viral infection cycle?
The prophase stage
What type of viral infection is Lambda phage capable of?
Lyric and lysogenic
What is zoonoses?
An infection that is transferred from animals to human
What is a vector?
An organism that transmits a disease
What is the transmission of a viral infection through infected surfaces of objects be categorised as?
Indirect mode of transmission
What is election microscopy?
A technique used to identify a virus based on its morphology
What is Zia virus transmitted by?
Vector mediated transmission
What are retroviruses?
Group of RNA viruses which insert a DNA copy of their genome onto the host cell in order to replicate
What is HIV?
Retrovirus
What can be used to treat viral infections?
Antivirals and antiserum
What are the main stages in B cell development?
Stem cells>pre-B cell>immature naive B cell>mature naive B cell
What is the maturation of B lymphocytes?
B progenitor cell>immature B cell>circulation>peripheral lymphoid organs>mature B cells
What are epitopes composed of?
Adjacent amino acid strings at different points
What do T independent activation cells result in?
Short lived plasma cells secreting IgM
What do T dependent activation cells result in?
Long lived plasma cells secreting high affinity IgG, IgA and IgE
What happens in T independent activation?
B lymphocyte activation>clonal expansion>differentiation>plasma cells
What is an advantage of T dependent B cell activation?
Ability to class switch
What is class switching?
Changing the constant regions of the heavy chains
What are polyclonal antibodies?
Immunochemically dissimilar antibodies that react with different epitopes of an antigen
What are monoclonal antibodies?
Immunochemically identical antibodies that react with the same epitope of an antigen
What is the complement enzyme cascade?
A complex system of proteins that acts as a cascade with each protein reacting in sequence once the system has been activated
What are functions of the complement system?
Complement the functions of other immune cells
What is MBL?
Mannose binding lectin
What does MBL do?
Binds to mannose residues on pathogen surfaces
What is opsonin?
A substance which binds to pathogens making them more susceptible to phagocytosis
What is opsonisation?
A process by which a pathogen is marked of ingestion and destruction by a phagocyte
What does the immune system do?
Protects body from invading microorganisms
What is smallpox caused by?
Variola major virus
Why can we eradicate the small pox?
No animal reservoir
Lifelong immunity
Subclinical cases rare
Effective vaccine
Major commitment by governments
Who proved the theory of disease and invented the process of pasteurisation?
Louis Pasteur
Who discovered tuberculosis?
Robert Koch
What do sebaceous glands secrete?
Fatty acids and lactic acid which lowers pH of skin to 4-6
Why does normal microbial flora of skin/mucous surfaces inhibit colonisation by pathogens?
They secret anti microbials
Good at obtaining nutrients
Alter environmental conditions
What do body fluids contain?
Bacteriocidal substance
What are the primary lymphoid organs?
Thymus
Bone marrow
What is bone marrow?
Site of generation or all circulating blood cells
Site of differentiation and maturation of white blood cells
Site of immune response of B cells
Site of B cell maturation
What are the secondary lymphoid organs?
Adenoids
Tonsils
Lymph nodes
Spleen
Peyer’s patches
Appendix
What are lymph nodes?
Contain high concentrations of leukocytes that filter out microbes and toxins
Structure of lymph nodes
Outer cortex filled with lymph follicles
Inner medulla
What is lymphatic filariasis?
Infected lymphatic system
What does the spleen do?
Filters out older red blood cells
Responds to antigens in circulatory system
Produces activated B cells
Stores platelets
What are functions of monocytes/macrophages?
Destroy bacteria by phagocytosis
Activate other immune functions
Phagocytise apoptotic cells
What are neutrophils?
Type of granulocytic white blood cells
What do neutrophils do?
First responders of inflammatory cells to migrate towards the site of inflammation
Structure of neutrophils
Dense nucleus consisting of 2-5 lobes
Irregular outline
Pale cytoplasm containing fine pink/grey-blue granules
What is an eosinophil?
Make up 1.5% of the total number of white cells
What are mast cells?
React immediately when allergenic substance enters the body
Types of white blood cells
Neutrophil
Eosinophil
Basophil
Lymphocyte
Monocyte
Macrophage
Dendritic cells
What are antigen presenting cells?
Specialised white blood cells that help fight off foreign substances that enter the body
What is an antibody?
An immunoglobulin secreted by cells after activation by an antigen
What is an antigen?
A substance capable of binding specifically to an antibody resulting in an immune response
What is the variable region?
Antigen binding region
What are light chains divided into?
K or I consisting of about 230 residues
What are heavy chains
µ,δ, γ, α, ε consisting of 450-600 amino acids
What are the 5 major classes of immunoglobulin molecules?
IgG, IgM, IgD, IgA, IgE
What is IgG?
Most abundant in serum
Plays an important role protecting the foetus
2 heavy and 2 light chains
4 subclasses
What is IgM?
5-10% in serum
Primary response to antigen
10 heavy and 10 light chains
What is IgA?
10-15% in serum
External secretions
Found in breast milk
What is IgE?
Lowest concentration in serum
Very potent
Mediate hypersensitivity reactions
What is IgD?
0.2% in serum
Membrane receptor on B lymphocytes
