Download antigen, acute phase response 2014

THE TWO ARMS OF THE IMMUNE SYSTEM
Monocytes/Macrophages,
Dendritic cells,
Granulocytes
NK cells
(complement system)
B and T lymphocytes
INNATE IMMUNITY
ADAPTIVE IMMUNITY
- immediate reaction communication - developes in several days
- not antigen-specific
- specific
- no memory
- has memory
Humoral immunity
Cellular immunity
!!
Innate immunity as a first line of defence
!!
Innate immune cells recognize frequently found structures of
pathogens by PRRs ,
these are not found in human cells!
PRRs (pattern recognition receptors) are responsible for recognize conserved
structures of the microbes
Examples of recognited structures:
duple strain RNA
bacterial cell wall components
bacterial flagellin….
Recognition is inevitable
ACUTE INFLAMMATION
AND
ACUTE-PHASE RESPONSE
ACUTE INFLAMMATION
A rapid response to an injurious agent that serves to
deliver leukocytes and plasma proteins to the site of
injury
THE INFLAMMATORY RESPONSE
TRIGGERS OF ACUTE INFLAMMATION:






Infections
Trauma
Physical and Chemical agents (thermal injury, irradiation, chemicals)
Tissue Necrosis
Foreign bodies (splinters, dirt, sutures)
Hypersensitivity or autoimmune reactions
MAJOR COMPONENTS OF INFLAMMATION:
1.
Vascular response:

Increased vascular diameter  Increased flood flow.

Endothelial cell activation

increased permeability that permits plasma proteins and leukocytes to
leave the circulation and enter the tissue  edema

increased expression of cell adhesion molecules e.g. E-selectin, ICAM
2.
Cellular response:

Migration of leukocytes (diapedesis/extravasation), accumulation, effector
functions
Immunitas = exemption, protection
Protection from / against what?
Self or non-self substances?
(What about the useful bacteria living together with us and what about
tumors in this model?)
- „Danger model”:
(Matzinger P., The danger model: a renewed sense of self. Science. 2002
Apr 12;296(5566):301-5.)
- harmful self / harmless self
- harmful non-self / harmless non-self factors!
DANGER SIGNAL / NO DANGER SIGNAL
-
obligate pathogen
facultative pathogen (Staphylococcus aureus)
CLASSICAL SYMPTOMES OF ACUTE
INFLAMMATION:
•
•
•
•
•
Redness (rubor)
Swelling (tumor)
Heat (calor)
Pain (dolor)
Loss of function (functio laesa)
NEUTROPHIL GRANULOCYTES
• 68% of circulating leukocytes, 99% of circulating
granulocytes
• Phagocytic cells
• Are not present in healthy tissues
• Migration  elimination of pathogens (enzymes, reactive
oxygen intermediates)
• Main participants of acute inflammatory processes
MIGRATION OF NEUTROPHILS
PUS
Pus is a whitish-yellow, yellow, or yellow-brown exudate produced by
vertebrates during inflammatory pyogenic bacterial infections. Pus consists of
a thin, protein-rich fluid, known as liquor puris, and dead cells.
CONSEQUENCES OF MACROPHAGE ACTIVATION
SYNTHESIS OF CYTOKINES
ACUTE-PHASE REACTION
proinflammatory cytokines
hypothalamic control of
body temperature
increased ‚set-point’ value
fever
ACUTE PHASE REACTION
IL-6
Complement
C-reactive protein
(CRP)
Liver
Fibrinogen
Serum amyloid
protein (SAP)
Mannose
binding
lectin/protein
MBL/MBP
UNDER THE INFLUENCE OF IL-6 THE LIVER PRODUCES A
BUNCH OF ACUTE-PHASE PROTEINS
OPSONIZATION
Opsonization facilitate and accelerate the recognition of the pathogen by phaogocytes,
opsonins form a bridge between pathogen and a phagocyte connecting them.
Main opsonins:
antibodies
Complement fragments
Acute-phase proteins
!!
ACUTE-PHASE RESPONSE
Pentraxin family:
CRP – opsonization, complement activation
SAP – opsonization, complement activation,
binding of mannose/galactose
Collectin family:
MBL – part of the complement system
(SP-A/D – collectins of lungs)
Complement proteins (C1-C9)
Fibrinogen  blood clotting
Plasma cascade systems
The complement system, when activated, creates a cascade of chemical
reactions that promotes opsonization, chemotaxis, and agglutination, and
produces the MAC.
The kinin system generates proteins capable of sustaining vasodilation
and other physical inflammatory effects.
The coagulation system or clotting cascade which forms a protective
protein mesh over sites of injury.
The fibrinolysis system, which acts in opposition to the coagulation
system, to counterbalance clotting and generate several other
inflammatory mediators.
CHEMICAL MEDIATORS
 Vasodilation
– Prostaglandins (PG), nitric oxide (NO)
 Increased vascular permeability
– vasoactive amines (histamine, serotonin), C3a and C5a
(complement system), bradykinin, leukotrienes (LT), PAF
 Chemotactic leukocyte activation
– C3a, C5a, LTB4, chemokines (e.g. IL-8)
 Fever
• IL-1, IL-6, TNFα, PGE2
 Pain
• Prostaglandins, bradykinin
 Tissue damage
• Neutrophil and Macrophage products
– lysosomal enzymes
– Reactive oxygen species (ROS)
– NO
NSAIDs and Paracetamol:
inhibiting COX-1 and COX-2
 preventing the synthesis
of prostaglandins
Prosztaglandin-E2
CHEMICAL MEDIATORS
 Vasodilation
– Prostaglandins (PG), nitric oxide (NO)
 Increased vascular permeability
– vasoactive amines (histamine, serotonin), C3a and C5a
(complement system), bradykinin, leukotrienes (LT), PAF
 Chemotactic leukocyte activation
– C3a, C5a, LTB4, chemokines (e.g. IL-8)
 Fever
• IL-1, IL-6, TNFα, PGE2
 Pain
• Prostaglandins, bradykinin
 Tissue damage
• Neutrophil and Macrophage products
– lysosomal enzymes
– Reactive oxygen species (ROS)
– NO
NSAIDs and Paracetamol:
inhibiting COX-1 and COX-2
 preventing the synthesis
of prostaglandins
Tissue factor :
Subendothel sejtek (simaizom, kötőszövet)
+endotél, makrofág TNF, edotoxin hatására
Kinin rendszer a vérből kilépve aktiválódik
+faktor XII prekallikrein-kalikrein—bradikinin
PAF, állandóan termelődik. Pl. platlets, endotél, neutrofil, monocita
De + makrofág, endotél stimulusra.
No
Makrofág (fagociták), endotél TNF-re fokoz
Leukotrién:
Hízósejt, leukociták aktiváció hatására
Prostaglandinok:
COX1 konstitutív
COX 2 leukocita, makrofág stimulusra, hipotalamusz
CHEMICAL MEDIATORS
 Vasodilation
– Prostaglandins (PG), nitric oxide (NO)
 Increased vascular permeability
– vasoactive amines (histamine, serotonin), C3a and C5a
(complement system), bradykinin, leukotrienes (LT), PAF
 Chemotactic leukocyte activation
– C3a, C5a, LTB4, chemokines (e.g. IL-8)
 Fever
• IL-1, IL-6, TNFα, PGE2
 Pain
• Prostaglandins, bradykinin
 Tissue damage
• Neutrophil and Macrophage products
– lysosomal enzymes
– Reactive oxygen species (ROS)
– NO
NSAIDs and Paracetamol:
inhibiting COX-1 and COX-2
 preventing the synthesis
of prostaglandins
RESOLUTION OF ACUTE INFLAMMATION
SEPTIC SHOCK
Triggering factors :
• systemic infection (bacteraemia)
• microbial cell wall products and/or
toxins released from the pathogens
Result:
Systemic activation of
neutrophils and macrophages

High level of cytokine (TNF-alpha) production:
„cytokine storm”

Excessive inflammatory response
SEPTIC SHOCK
The key molecule of the process: TNF-alpha
TNF-alpha and other inflammatory cytokines
capillar permeability
blood pressure
high fever
multiorgan failure
DIC
disseminated
intravascular
coagulation
Therapy: anti-TNF-alpha antibody
DIC
Disseminated Intravascular Coagulation
• pathologic activation of
thrombotic process
• distress of thrombotic
process, bleeding
• other causes:
snake bite, septic
abortion, acute obstetric
complications, malignant
tumors, leukemias
DIC: Disseminated Intravascular Coagulation
2nd seminar:
THE ANTIGEN
Definition and properties
Antigenic determinant (epitope)
Hapten, carrier
Antigen recognition by B and T cells
Superantigens
ACUTE
INFLAMMATION
DEFINITIONS
• ANTIGEN (Ag) - any substance, which is
recognized by the mature immune system
of a given organism
Any chemical structure
Soluble or corpuscle
Simple or complex
Originated from the body or comes from outside
Genetically self or non-self
Natural or artificial
DEFINITIONS
• ANTIGENICITY– capability of an antigen to bind
specifically with certain product of the adaptive
immunity: TCR or BCR/antibody,
– immunogenicity - capability of an antigen to induce an
(adaptive) immune response,
– tolerogenicity - capability to induce immunological
tolerance, specific immune non-responsiveness
FACTORS INFLUENCING
IMMUNOGENICITY I.
From the aspect of our body:
• Genetics (self/non-self)
–
–
species (evolutionarily nonconserved molecules)
individual differences (e.g. MHC polymorphism – see later)
• Age
– newborn – less reactive immune system
– elderly – no new lymphocytes
• Physiological condition (pl. immunodeficiencies,
starvation)
FACTORS INFLUENCING
IMMUNOGENICITY II.
From the aspect of the antigen:
• Physical-chemical properties of the Ag
–
–
–
–
size/complexity (bigger  more epitopes, role of carrier)
corpuscular (cell, colloid) or soluble
denatured or native (different epitopes!)
degradability (by APCs)
• Availability (crystalline proteins of the eye are not
presented to lymphocytes)
FACTORS INFLUENCING
IMMUNOGENICITY III.
From the aspect of vaccination:
• Dose
• Route
– intradermal/subcutan > intravenous > oral > intranasal
(oral vaccine against polio virus!)
• Adjuvant
– enhance the response given to the antigen
e.g.: alum, Freund-adjuvant, TLR ligands
Complex effects:
• depot effect  long-lasting presence of antigen
• activation of innate immunity
• activation of bystander cells
077-298-32------------------218-329-10
HLA-C
HLA-B
HLA-A
maternal
HLA-A
HLA-B
HLA-C
paternal
ANTIGEN RECOGNITION BY LYMPHOCYTES
antibodies (serum Ig)
APC
Antigen
MHC
BCR
TCR
(membrane Ig)
T
B
B cells recognise native antigens
T cells recognise processed antigens
Clonal proliferation
!!
LYMPHOID ORGANS
Primary lymphoid organs:
- Bone marrow
- Thymus
the cells of the immune system
originate in and mature here
Secondary lymphoid organs:
- Spleen
- Lymphatic vessels
- Lymph nodes
- Adenoids and tonsils
- MALT (Mucosal Associated Lymphoid Tissue)
GALT (Gut Associated Lymphoid Tissue)
BALT (Bronchus Associated Lymphoid Tissue)
SALT (Skin Associated Lymphoid Tissue)
NALT (Nasal Associated Lymphoid Tissue)
not for cell development. (final differentiation, activation
may be performed) The cells of the adaptive immune
system recognize here the pathogens
DEFINITIONS
• ANTIGEN (Ag) - any substance, which is
recognized by the mature immune system
of a given organism
Any chemical structure
Soluble or corpuscle
Simple or complex
Originated from the body or comes from outside
Genetically self or non-self
Natural or artificial
ANTIGENIC DETERMINANT (=EPITOPE)
Part of the antigen
which directly interacts
with the antigenbinding site of a
defined
immunoglobulin
(BCR / antibody)
or TCR
B cell epitope
T cell epitope
recognized by B cells
recognized by T cells
• proteins
polysaccharides
lipids
DNA
steroids
etc. (many artificial
molecules)
• proteins mainly
(8-23 amino acids)
• cell or matrix associated
or soluble
• requires processing by
APC
Antigens may have several different epitopes
T CELL-DEPENDENT B CELL ACTIVATION
1
B cell
MHCII
+peptide
T cell
CD4
TCR
2
cytokines
gr2
Polysacharides are not presented!
Theoretical structure of complex antigens
Epitopes
„Carrier”
no direct interaction with the
antigen-binding site
These terms can only be used to describe the
interaction of particular antigenic determinant
and single immunoglobulin or T cell receptor
EPITOPE AND „CARRIER”
Antibody 1
„carrier” (2)
Antibody 2
Epitope 1
Antigén
Epitope 2
„carrier” (1)
TYPES (STRUCTURE) OF ANTIGEN DETERMINANTS
linear determinant
(TCR, BCR, Ig)
conformational determinant
(BCR, Ig)
conformational
determinant Ab2
Ab1
surface/accessible
determinants
cleveage
denaturation
new/neoantigen
determinant
conformational/linear
determinant
hidden/revealed
determinant
LPS – antigen or PAMP?!
Antigen
PAMP
if recognised by TCR/BCR
if recognized by PRR (TLR4)
Fc
LPS
Fab
side view
Fab
specific antibody reactive to the
glucoseamin epitope of LPS
top view
T CELL-DEPENDENT B CELL ACTIVATION
1
B cell
MHCII
+peptide
T cell
CD4
TCR
2
cytokines
Polysacharides are not presented!
B CELL ACTIVATION WITHOUT THE HELP OF T CELLS
T-INDEPENDENT ANTIGEN
TI-1
T-INDEPENDENT ANTIGEN
TI-2
B cell
Simultaneous activation of BCR and
other receptors on B cells (i.e. LPS
binding protein /CD14) induces the B
cells to proliferate and differentiate
(extra activation signal)
Strong crosslinking of BCR by
repetitive polysaccharide or
protein epitopes
B CELL ACTIVATION
(extensive receptor-aggregation)
B CELL ACTIVATION WITHOUT THE HELP OF T CELLS
Gr1-gr9
HAPTEN
molecules that are too small to provoke an immune
response unless they are attached to carriers
hapten
(e.g. DNP: dinitrofenil)
carrier + haptens
+
HAPTEN
free haptens
haptens attached to a carrier
0
receptor cross-linking 
signalization
Antibody response generated against a haptencarrier conjugate
carrier + hapten
antibodies
carrier specific
hapten specific
carrier + hapten
specific
ANTIGEN RECOGNITION ≠ CELL ACTIVATION
ANTIGEN RECOGNITION BY NAIVE T CELLS REQUIRES
PRESENTATION VIA MHC MOLECULES
Recognition/
No activation
Recognition/
Activation
EXAMPLE (Prevenar - pneumococus vaccine)
Purified bacterial polysacharides used for vaccination do not lead to long-lasting
immunity because the activation of T cells is required for memory B cell formation
Hence the polysaccharide chains are conjugated to protein carriers which can activate
T cells
Carrier: CRM197  modified diphteria toxin (toxoid)
(a single aminoacid change (Glu  Gly) in the toxin can abolish toxicity)
The toxoid acts the same way the toxin does; it activates specific T cells and may lead
to the production of antitoxins by plasmacells
Glu  Gly
toxin
+
polysaccharides of
different Streptococcus
pneumoniae strains
toxoid
toxoid
complex antigen of vaccine
toxoid
peptide
antigen
derived
from toxoid
polysacharid
MHCII
BCR
B cell
specific to
bacterial
polysaccharid
TCR
T cell
specific to
toxin/toxoid
epitope
cytokines,
CD40-CD40L
formation of pneumococcusspecific memory B cells
SUPERANTIGENS
Microbial proteins that bind to and activate all the T cells that express
a particular set or family of TCR molecules resulting in a polyclonal
activation
Fever
SUPERANTIGENS
Microbial proteins that
bind to and activate all
the T cells that express
a particular set or
family of TCR
molecules resulting in a
polyclonal activation.
Interaction is not via the
peptide binding cleft of
MHC molecule.
Hypotension
Rash
Desquamation
SUPERANTIGENS
Microbial proteins that bind to and activate all the T cells in an individual
that express a particular set or family of TCR molecules
conventional antigen
superantigen
monoclonal/oligoclonal
polyclonal
T cell response
T cell response
1:104 - 1:105
107 – 108 / 1011
activated T cells
1:4 - 1:10
1010 / 1011
SUPERANTIGENS
Classification
Sources
Endogenous
1.Mouse mammary tomor virus (MMTV)
2.Epstein-Barr virus (EBV)
Exogenous
1.Staphylococcal enterotoxins (SEs): A, B, C1 to C3, D, E, G to Q
2.Staphylococcal toxic shock syndrome toxin-1 (TSST-1)
3.Staphylococcal exfoliative toxins: exoliatin A, exfoliatin B
4.Staphylococcal enterotoxin-like toxins formed due to recombination within enterotoxin gene cluster:
U2, V
5.Streptococcal pyrogenic exotoxins (SPEs): A1 to A4, C, G to M
6.Streptococcal mitogenic exotoxins: SMEZ
7.Streptococcal superantigen :SSA
8.Yersinia pseudotuberculosis: Yersinia pseudotuberculosis-derived mitogen (YAM)
9.Mycoplasma species: Mycoplasma arthritidis-derived mitogen (MAM)
10.Cholera toxin: subunit A of cholera toxin
11.Prevotella intermedia*
12.Mycobacterium tuberculosis*
13.Viral superantigens: (a) Mouse leukemia virus
(b) IDDMK1222- Ppol-ENV-U3
(c) HIV-Nef
(d) Rabies virus-nucleoside protein
.