Summary
Samenvatting Immunology (I0I20a)
- Module
- Institution
Summary of 103 pages for the course Immunology at KU Leuven
[Show more]
Seller
Follow
feline2
Reviews received
Content preview
IMMUNOLOGY: Part 1: Introduction to immunobiology and innate immunity (p1-36)1. Chapter 1: Basic concepts in immunology
• Zie extra papieren
• In plant & animal kingdom: looked at NOD like receptors (NLR) (innate immunity) (zie extra)
o = sense presence of pathogens in terms of biomolecules => then immune respons that react to a
CLASS of pathogens (vb funga, virus) (not to specific pathogen)
• Summary of molecules of the immune system & innate and adaptive immune characteristics
o Adaptive immunity = responds to specific pathogen & adapts when organism encounters that
specific pathogen during lifetime
▪ Vb: antibody production against particular pathogen as defense
o Innate immunity = immunity inherited from parents = basic level of immunity (always present) =
fixed genes that respond to pathogens, but independent of pathogen you encounter (nonspecific) +
no adaptation (ppt: from Classical down)
▪ Vb: macrophages engulf many MO as defense (nonspecific; always present)
o => Innate & adaptive immune system integrate to give immune respons
• Edward Jenner
o Invention: vaccination = inoculation of healthy people with weakened or attenuated strains of
disease-causing agents in order to provide protection from disease
o Process: Cows have pox virus that gives lesions to uiers/tiets => milk maids exposed & infected by
pox virus (not lethal) did also not get sick by variola virus (lethal)
▪ => isolates from pox virus became vaccination for variola virus
o Gevolg: Eradication of small pox (variola) by vaccination (small pox vaccination)
• Origin of vertebrate immune cells
o Immune system = effector cells that protect body from infectious agents & their toxins (immune
cells reside in blood stream, lymphatic system, peripheral tissues)
o Both innate & adaptive immune respons ~ activity of leukocytes or white blood cells
o 1) All cellular elements of bloods, including immune cells, derive from the hematopoietic stem cells
(HSCs) of the bone marrow = pluripotent (give rise to different types of cells)
o 2) HSCs divide to produce two types of stem cells
▪ 1) Common lymphoid progenitor (CLP): gives rise to lymphoid lineage (blue) of white blood
cells or leukocytes – innate lymphoid cells (ILCs), natural killer (nK) cells & T & B lymphocytes
• T & B lymphocytes have antigen receptors ILCs & NK cells lack antigen specificity
• T & B lymphocytes have different site of differentiation: thymus (T) & bone marrow
(B)
o After encounter with antigen: B cell differentiate into antibody secreting
plasmacells & T cells differentiate into effector T cells
▪ 2) Common myeloid progenitor (CMP): gives rise to myeloid lineage (pink & yellow), which
compromise the rest of the leukocytes (monocytes, dendritic cells, neutrophils, eosinophils,
basophils), erythrocytes (red blood cells) & megakaryocytes that produce platelets
• Neutrophils, eosinophils, basophils = circulate in blood = granulocytes (cytoplasmic
granules)
• Immature dendritic cells = phagocytic cells that enter tissues; maturation after
encountering a pathogen; majority from myeloid, some from lymphoid progenitor
• Monocytes = enter tissues and differentiate then into macrophages or dendritic cells
• Mast cells (allergies) = also enter tissues & complete their maturation there
▪ Opm: 2 categories leukocytes: lymphoid (adaptive: T,B,NK) & myeloid (innate: neutrophils..)
▪ Opm : erythrocytes (carrier O2): not immune cells, but role in immune respons via receptors
Principles of innate immunity
1
,• Classification of immune cells = based on surface markers & signaling molecules
o Surface markers = called cluster of differentiation, used for immunophenotyping of lymphocytes
▪ Vb: CD4 (helper) & CD8 (killer) markers for T cells (they allow to differentiate in T effectors)
B cell has antibody on its surface (both for antigen detection????)
o Signaling molecules = effector molecules (cytokinines & chemokines) expressed by lymphocytes
▪ Vb: IL17 (cytokinine?) associated with specific set of T lymphocytes
• Density gradient centrifugation to isolate vb: lymphocytes (isolate a specific celltype) in blood
o = separation according to celltype: cells with large volume = lower relative density compact
o Gevolg: based on density some cells will float, others will sink
• Evaluation of the cellular components (T,B,monocytes,…) of the human immune system
o => if you have immune response, amount of cells in blood & amount of antibodies will change
o 1) Blood values can indicate an normal or a pathological condition
▪ Vb: increase in neutrophiles, show early infection
o 2) Antibody/immunoglobin measurement can also indicate normal or a pathological condition
▪ Vb: increase in IgE, you have an allergy or a parasite
▪ Vb: measure type of heavy chain: igM represents early stage of immune respons igG
represents older stage of immune respons => see if exposure to parasite was recent or later
• FACS analysis: cytometrie to zoom in in population (sorted out via gradient density) to a certain subtype
o = uses antibodies, labeled with fluorofoor, to detect a specific antigen
o 1) Navigate these as single cells via narrow channel
o 2) Different lasers to excite the fluorofoor & a detector
o => like this figure out which antigens are on the surface (& thus which surface markers)
• Magnetic-activated cell sorting (MACS) to isolate cells in heterogenous population of lymphocytes (ipv
identify)
o = uses same technology as FACs, but now antibodies coupled to paramagnetic particles/beads
o 1) Use magnetic field to capture these cells & unlabeled cells are washed out
o 2) Magnetic field is removed, releasing the coupled cells (& see thus which surface markers)
• Thin film (old school)
o = technique to find out if there is inflammation
o 1) Drip of blood & pull one microscope slide over the other slide => result: thin film of blood
o 2) Fix cells & color cells with GEIMSA vb: basophilic dye colors DNA & acidic one colors cytoplasma
o 3) Count nr of cell: if neutrophiles nr is much higher = early stage of inflammation
• Commensal organisms cause little host damage while pathogens damage host tissues by a variety of
mechanisms
o Pathogens vary in size & lifestyle vb viruses small parasites larger
o But same immune cells (cells of innate & adaptive immune system with diff surface markers & signal
molecules) defend against these pathogens
• Protection against pathogens relies on several levels of defense
o Anatomical and chemical barriers are the first defense against pathogens
o 1) Anatomical barriers: provided by body’s epithelial surfaces: skin, oral mucosa, respiratory
epithelium, intestine (prevent exposure to microbes
o 2) Complement/antimicrobial proteins: chemical and enzymatic systems: C3, defensines, Regilly
▪ = act as antimicrobial barrier near these epithelia (mucosa produce antimicrobial proteins)
▪ Complement = acts with antibodies to lyse bacteria
• Blood: serum, proteins, unhabitable for pathogen => part of this is because of
complement system (effectors in serum)
• Complement system needs to differentiate between pathogens & host cells (both
made up by biomolecules DNA, proteins,..) => regulation done by C3, defensins,
Regilly => complement acts against pathogens & leaves host cells alone (??)
2
, o 3) If anatomical barriers are breached or evaded, other components of the innate immune system
can act: macrophages, granulocytes, natural killer cells (in antigen independent way kill host cells)
o 4) If pathogen overcomes barriers, slower acting defenses of adaptive immune system act: B
cells/antibodies, T cells
• Cell-mediated immunity proceeds in a series of steps
o A pathogen that breaches host barriers (1): encounters cellular defenses of innate immunity
o 1) The immune system is activated by inflammatory inducers that indicate the presence of
pathogens or tissue damage: bacterial lipopolysaccharides, ATP, urate crystals
o 2) Sensor cells (macrophages, neutrophils, dendritic cells) detect these inducers by expressing innate
recognition receptors:
▪ & in response produce mediators (cytokinines, cytotoxicity: can kill cells) that act directly in
defense or further propagate the immune respons
▪ & they act on various target tissues vb endothelial tissue for production of antimicrobial
proteins & induction of intracellular antiviral proteins ; killing of infected cells (cytotoxins); or
vb other immune cells (NK cells, ILCs)
• Summary innate vs adaptive immune system (tekening S45)
o Innate (macrophages, monocytes,..) (zie verder)
▪ 1) Have Toll like receptors
▪ 2) Nod receptors in cytoplasma
o Adaptive (B cell (secrete antibodies) (plasmacell special one), T cell (CD4+/Helper, CD8+/Killer)
(parallel with CD8% u have NK cells in innate immunity)
▪ Helpercells produce cytokines (effectors) & killer cells produce toxins (effectors)
o Exam: see extra paper (can copy paste in front of book; or make these at paper question)
• Phases of the immune respons (time)
o Innate immune respons: occur rapidly on exposure to infectious agent (min) ; first fast responders
o Adaptive immune respons : take days rather than hours to develop; slow responders
▪ Adaptive immunity recalls pathogens they encountered (memory) => so next time they
encounter same pathogen, you can respond quicker
▪ but adaptive respons eliminate infections more efficient because of specificity of antigen
recognition by lymphocytes innate
o Immunological memory = adaptive immune system can generate this = if you have been exposed
once to a pathogen, u will make a stronger & faster response against any subsequent exposure to it
▪ = memory that can last depending on the pathogen from days/weeks/months to lifelong
immunity (vb vaccin will protect you 4-6 months)
• Myeloid cells in innate & adaptive immunity and their activated function
o CMP = precursor of macrophages, granulocytes (white blood cels: neutrophils, eosinophils,
basophils), mast cells, and dendritic cells of the innate immune system
o 0) Monocyte = progenitor of macrophage, in blood => when monocyt leaves blood it can
differentiate into a macrophage (different phenotypes depending on tissue)
o 1) Neutrophils & Macrophages = phagocytic cells that engulf pathogens (clean up) and destroy them
in intracellular vesicles via bactericidal mechanisms (function in both A&I respons)
▪ => macrophages can also present antigens to T lymphocytes & activate T lymphocytes &
initiate A respons (=antigen presentation) neutrophils
▪ => neutrophils role in inflammation: typical adaptive immune responses in different
compartments, and one compartment recruit neutrophils
▪ => macrophages orchestrate immune response: help induce inflammation which is
prerequisite to succesful immune response & produce inflammatory mediators that activate
other immune system cells & recruit them into an immune respons (~ complement)
o 2) Dendritic cells = are phagocytic when they are immature & can take up pathogens
▪ => after maturing, they are specialized cells that present pathogen antigens to T
lymphocytes & activate T lymphocytes & initiate A respons (= antigen presentation)
3
, ▪ => dendritic cells orchestrate immune respons also (“): emit cytokinines to
orchestrate/navigate immune respons
o 3) Eosinophil (lot of granules) = killing of antibody-coated parasites vb worms via granules
o 4) Basophil (lot of granules) = promotion of allergic responses & anti-parasitic immunity
o 5) Mast cell (even more granules) = release of granules containing histamine & active agents when
encountering antigen => content act on local blood vessels (vasoconstriction) => like this trigger local
inflammatory respons to antigens
o Opm: mast cells, eosinophils, basophils = important in allergic responses & are secretory cells that
release content of granules upon activation via antibody during an adaptive immune respons
• Sensor cells (macrophages, neutrophils, dendritic cells) express (innate) pattern recognition receptors (PRRs)
o 1) that provide an initial discrimination between self & nonself
o 2) that thus detect pathogens or the damage induced by them
o Via recognizing regular patterns of molecular structure = pathogen-associated molecular patterns
(PAMPs) that are part of many MO (nonself biomolecules), but NOT of the host body’s own cells (self
biomolecules) => necessary bec all organisms are made up by same biomolecules DNA, RNA,…
o Voorbeeld van PRR’s:
▪ 1) Toll like receptors (TLRs) = transmembrane proteins = detect PAMPs derived from
extracellular bacteria or bacteria taken into vesicular pathways by phagocytosis
▪ 2) NOD like receptors (NLRs) = cytoplasmic proteins = sense intracellular bacterial invasion
o But auto immune disease (see further): antibodies detect normally peptidic antigens, but there is
something wrong & they now detect host own antigens
• Infection triggers an inflammatory response:
o Activation of PRR on sensor cells can directly induce effector functions vb phagocytosis & destroying
bacteria => but sensor cells also amplify the immune respons by production of inflammatory
mediators (cytokines, chemokines) & like this induce inflammatory response
o 1) Bacteria trigger macrophages to release cytokines and chemokines (left)
o 2) Gevolg cytokines: vasodilatation and increased vascular permeability => allowing fluid and
proteins to pass into the tissues => this accumulation causes redness, heat and swelling (central)
o 3) Gevolg chemokines: direct the migration of neutrophils to site of infection (central)
o 4) Stickness of endothelial cells of blood vessel wall also changes => hereby immune cells
(inflammatory cells: neutrophils & monocytes/macrophages) enter tissue from a blood vessel
▪ Inflammatory cells in tissue, release inflammatory mediators that cause pain by triggering
pain receptors
o Accumulation of fluid + cells at site of infection => causes redness, heat and swelling and pain
▪ = inflammation
• Innate lymphocytes and natural killer cells are effector cells that share similarities with lymphoid lineages of
the adaptive immune system
o CLP give rise to antigen specific lymphocytes of the adaptive immune system (B, T cell) & to innate
lineages that lack antigen specific receptors (NK)
o Natural killer cells (NK) (innate immune equivalent of cytotoxic T cell)
▪ = large granular lymphoid like cells with functions in innate immunity (especially against
intracellular infections) & can kill other cells (via lytic granules similar to CD8+ T cells)
▪ Opm: they lack antigen-specific receptors & are additional layer of surveillance
Principles of adaptive immunity
• Interaction of antigens with antigen receptors induces lymphocytes to acquire effector & memory activity
o Lymphocytes = small & inactive cells (little cytoplasm, large nucleus), until they encounter a specific
antigen with their antigen receptor => become active or effector lymphocytes (cytoplasm increases)
o 1) B lymphocytes (plasmacell)
▪ B cell antigen receptor (BCR): made of genes that encode antibodies (igE; immunoglobulins)
4
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller feline2. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £8.56. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
64438 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now