Immunology Flashcards
what is innate immunity
The body’s first line of defence which can be both physical and chemical (non specific, natural, native)
Give examples of physical and chemical defences
Physical : skin, mucosa, tears, mucus, saliva
Chemical: Fatty acids, lysozymes, commensal organisms
Define commensal organisms
uses food supplied by the host without establishing a close relationship with it
What is the role of commensal organisms
-colonise your cells
-support your immunity
by
- prevent adhesion, produce substances to inhibit growth or kill pathogens
Define inflammation
Recruit leukocytes into the tissues to destroy microbes
Define Antiviral
cytokine mediated reaction prevent viral replication + kill virus w NK cells
What is the 5 processes of commensal organisms
Recognise, respond, activate, eradicate, memory
What is the commensal recognise response
DAMPs = Damage associated molecular patterns
PAMPs = pathogen associated molecular patterns
released during times of trauma, Alarmin is a damp, to inhance immune response, PRR (Pattern recognition receptors) - these are detected ib blood, binding to these trigger downstream response
What is the commensal recognise response
Physical barriers (epithelial cells) - tight junctions, keratin,mucus .
What is the function of neutrophils in activate and eliminate phagocytes
in the earliest phase, circulate in blood for days or hours but once its hit tissues it lives max a day, relocate to site of infection, kill via phagocytosis, granules contain defensins (primary) and lysozymes (secondary), production stimulated G-CSF = regulatory growth factor
what is the function macrophage in activate and eliminate phagocytes
Circulate as monocytes, migrate to organs and connective tissues to mature, long lived, derived during fetal development, modified by m-CSF, granular cytoplasm containing lysosomes, monocytes identifiable by high CD14 and lack of CD16
What is adaptive immunity
specialized immune cells and antibodies that attack and destroy foreign invaders and are able to prevent disease in the future by remembering what those substances look like and mounting a new immune response
summarise humoral immunity
immune response mediated by antibodies and complement
summarise is cell mediated immunity
Immune response mediated by cells such as t lymphocytes
what is the difference between cell mediated and humoral immunity
humoral immunity produces antigen-specific antibodies, whereas cell-mediated immunity does not.
In cell mediated immunity its mediated by t lymphocytes cells, what about humoral ?
secreted antibodies in blood produced by B lymphocytes
humoral and cell mediated immunity whats the process
h- neutralise, tag and target circulating microbes for elimination
cm - destroy microbes which are within phagocytes or infected cells
What are the main features of humoral immunity
Its specific - antibodies respond to a specific antigen at a specific part called the epitope
Maintains homeostasis- avoid over stimulation returns to resting state to prepare for next time, lymphocytes undergo apoptosis
Memory- storing knowledge w the first encounter makes secondary immune response more rapid and larger due to long lived memory cells
Exapansive, diverse, nonreactive to self
overview b lymphocytes
From bone marrow, proliferate and produce antibodies 1 type, antibodies on outside acting as receptor, antibodies coat and promote destruction by phagocytosis, activate complement system, half life of a few days, three weeks or years, antibody secreting cells
What is antibody function
membrane bound antibodies act as antigen receptors to initiate humoral response, plasma cells secrete antibodies to neutralise toxins prevent entry of pathogens and elimate microbes, classical complement cascade by activating C1
Describe the classical complement pathway
C protein complex binds to the IG, only bound antigens can activate to complement pathwat, C1 must bind to 2+ heavy chains to be activated, C1r cleaves and activates C1s, C1s cleaves C4 to give c4a and c4b, c4b is bound to cell surface and can bind to pathogen, C2 binds to C4 and is cleaved into C2a and c2b, c2a remain bound to c4
Describe the antibody structure
2 heavy and 2 light chains, variable regions, constant regions, fc region- interracts w cell surface receptors and proteins of complement system for effector molecule binding, light chains only in fab region, heavy chains in fab and fc region
What are the five main types of igs and what is it
trigger effector functions once bound;
IgG = multiple functions
Igm = activated complement
IgA= main component of mucosal immunity
igd = main naive b cell antigen receptor
ige= activates mast cells
affinity vs avidity in antigen binding
Affinity= strength of one binding event
Avidity= strength of multiple epitope binding
What are monoclonal antidbodies
produce form a single clone of cells consisting of identical molecules
What is polyclonal antibodies
a mixture of antibodies produced from different clones of B lymphocytes that may each bind to different epitopes of an antigen
What is recomniant antibodies
in-vitro method to clone antibody genes
what is the differnce between innate and adaptive immunity
innate immunity provide initial defence against infections, adaptive immune response develop later and require the activation of lymphocytes
True or false, cell mediated immunity produces antibodies and responds to soluble antigens
false
What is the major histocompatibility complex ? (MHC)
What are the types of t cells?
Th= t helper cells
Tc= cytotoxic t cells
Treg = t regulatory cells
How can we tell the difference between the t cells?
each express different surface proteins called cd, they are recognised by monoclonal antibodies to allow identification of the cell
What happens to early t cells?
the early tells are cd4- and cd8-, TCR arrangement leads to cd4+ and cd8+, interacting w MHC class 1 they become CD8+ CTL, MHC class 11 they become CD4+ Th
overview t helper cells
express cd4+ , secrete cytokines which act as messenger molecules, stimulate proliferation and differentiation of t cells
Overview cytotoxic t cells
Express cd8+, kills cells w intracellular microbes which produce foreign antigens, cytotoxic granules release into target reducing collateral damage,
Perforin= builds pores in membrane for entry
Granzyme A = activates ssDNA breaks
Granzyme B = Activates, caspase cystine proteases to initiate apoptosis
Why is apoptosis better than necrosis
Apoptotic cells swiftly recognised by phagocytes before intracellular contents can leak
Minimises collateral damage to neighbouring cells
What do regulatory t cells do?
inibit the immune response to maintain homeostasis and ensure self tolerance
what is the natural killer t cells?
Express cd16 to recognise igG coated pathogens and dont have unique receptors
What are antigen presenting cells
cells that capture and display antigens to activate t lymphocytes, endogenous antigens produced within a cell presented as class 1 mhc (viral )and exogenous produced outside (bacterium) class 11 mhc
What is active immunity
a type of immunity following exposure to a foreign antigen where the individual plays an active role in responding to the antigen
What is passive immunity
immunity to an antigen when an individual receives antibodies or lymphocytes from another individual is immune to that antigen. They can then be immune to the antigen without ever being exposed to or reacting to that antigen. This is called adoptive transfer
Describe the escape strategies employed by microbes
Antigenic drift = point mutation in genes coding for immunogenic glycoproteins on the surface of the virus, leads to different presentation at a specific site
Antigenic shift= altering surface antigens by combing 2 dif strains, leads to a complete dif presentation
What is immunotherapy
treatment of disease with therapeutic agents that promotes or inhibits the immune response
What is the primary defence of the organism against the threat of diease
INVADE - MULTIPLY - SPREAD - PATHOGENESIS - RECOGNISE - RESPOND - ACTIVATE- ERADICATE- MEMORY
active vs passive immunity characteristics
Active is slow, long lived, generates immunological memory, low side effects, doesn’t work in an immunodeficient host.
passive is rapid response, short lived, no memory, works in immunodeficient host
What type of immunity is vaccines
active: specificity and memory
Describe the influenza vaccine TIV
3 strains dead flu evaccine
injected into upper arm
not for < 6 months
Describe the influenza vaccine LAIV
live weakened
Liquid into nose, not for ,2 years or > 49 pregnant or women or chronic diseases
Describe maternal antibodies
passive, neonates have immature immune systems so cant fully respond to antigenic stimulus. mostly IgG protect neonate during maturation, short lived in blood stream, IgA in breastmilk, infant can then make their own antibodies
what are escape strategies
hiding from the immune system y residing within the cells, interfering with the systems of a cell and generate escape mutations
p to avoid being a target of cytotoxic t cells
How does HPV hide from the host?
they lay dormant for years and the individual can be asymptomatic, once the host has lowered resistance the pathogen emerges
How does HIV hide from the host
gains access to immunology privileged sites - low lymphoid tissue in the vagina to avoid detection
How does influenza virus hide from the host
frequently changes the surface antigens which they display
How does Bacillus anthracis interfere with the function of the immune system
Secretes 3 different proteins, supresses pro-inflammatory cytokine secretion, prevents the inflammatory response
How does HIV interfere with the function of the immune system
hijacks CD4+ Th cells, degrades the host ability to mount a strong cell mediated response, increases susceptibility to other infections or tumours
How does Pseudomonas aeruginosa interfere with the function of the immune system
Inhibit C3A and C5A of the complement system, prevent MAC invasion to inhibit inflammatory response
How does the smallpox (variola major) destroy elements of the immune system
secretes proteins which inhibit complement enzymes and complete cascade, interferes w mhc class 1 proteins
How does hiv destroy elements of the immune system
target c-type lectin on dendritic cells to skew the T-cell response
How do tumours exhibit escape stratergies?
decrease expression of mhc class 1, supress immune system via t cell pathway and reduction of costimulators, high rate of genetic mutation or deletion
Describe monoclonal antibody therapy
multifunctional, blocks cellular functions, induces apoptosis, modulates signal pathways
radioimmunotherapy description
MAB is ocupled to a radioactive substance delivering a lethal dose to a specific cell line
antibody immunotherapy
antibodies linked to one or more drugs, when bound to target will release the drug and kill the cell, mixed results in clinical trials
What are the ways pathogens avoid destruction
hiding from the host, destroying or influencing the host immune response, developing virulence factors or genetic mutations
