Allergy and Autoimmunity Summary/Samenvatting

Allergy
and
Autoimmunity
Lecture
Summary
(November
2013).



Lecture
1:
Introduction,
Immunology
Basics.



Immune
system:
role
in
the
defense
against
invading
pathogens.

• Mechanical
barriers:
Skin,
Mucosa.

• Blood
circulation:
Bone
marrow,
Spleen.

• Lymph
circulation:
Thymus,
Lymph
node,
Specialized
lymphoid

structures
located
in
a
variety
of
organs
(e.g.
MALT
=
mucosa-­‐associated

lymphoid
tissue).











Cells
of
the
immune
system:


• Monocytes
circulate
in
the
blood.
When
monocytes
reside
in
tissue
they

differentiate
into
either
immature
DC
or
macrophages.

• Natural
killer
cell:
kills
cells
infected
with
certain
viruses.

• Neutrophil:
phagocytosis
and
killing
of
micro-­‐organisms.

• Eosinophil:
killing
of
antibody-­‐coated
parasites
through
the
release
of

granule
contents.

• Basophil:
unkown.

• Dendritic
cell:
activation
of
T-­‐cells
and
initiation
of
adaptive
immune

responses.

• Mast
cell:
expulsion
of
parasites
from
the
body
through
release
of

granules
containing
histamine
and
other
active
agents.

• Monocyte:
circulating
precursor
cell
to
macrophage.

• Macrophage:
phagocytosis
and
killing
of
micro-­‐organisms.
Activation
of

T-­‐cells
and
initiation
of
immune
responses.

• Small
lymphocyte:
production
of
antibodies
(B-­‐cells)
or
cytotoxic
and

helper
functions
(T-­‐cells).

• Plasma
cell:
fully
differentiated
form
B-­‐cell
that
secretes
antibodies.








1


,



Immune
response:
functions
in
the
defense
against
invading
pathogens.

• Innate
immune
responses
-­‐>
fast,
not
very
specific.

Adaptive
immune
responses
-­‐>
specific,
memory,
self/non-­‐self.



Defense
against
pathogens
in
3
steps:

1. Alarm
and
first
defense:
a-­‐specific
killing
of
pathogens
(quick
and
dirty),

local
inflammation.

2. Mobilization
of
the
immune
system:
recruitment
of
immune
cells
to
areas

of
infection,
activation
of
adaptive
responses
(specific)
-­‐>
antigen

presentation.

3. Specific
defense
and
future
protection:
clonal
selection
of
antigen-­‐specific

lymphocytes,
effector
B(plasma)-­‐cells
and
T-­‐cells,
memory.



Local
Inflammation:














2


, Neutrophils
-­‐>
killing:









• Large
reserves
of
neutrophils
are
stored
in
the
bone
marrow
and
are

released
when
needed
to
fight
infection.

• Neutrophils
travel
to
and
enter
the
infected
tissue,
where
they
engulf
and

kill
bacteria.
The
neutrophils
die
in
the
tissue
and
are
engulfed
and

degraded
by
macrophages.



Complement:

• Bacterial
cell
surface
induces
cleavage
and
activation
of
complement.

• One
complement
fragment
covalently
bonds
to
the
bacterium,
the
other

attracts
an
effector
cell.

• The
complement
receptor
on
the
effector
cell
binds
to
the
complement

fragment
on
the
bacterium.

• The
effector
cell
engulfs
the
bacterium,
kills
it
and
breaks
it
down.









Macrophges
initiate
effector
immune
responses
by
activating
T-­‐cells:


• Bacteria
binding
to
endocytic
receptors
of
macrophafes
induce
their

engulfment
and
degradation.

• Bacterial
components
binding
to
signaling
receptors
of
macrophages

induce
the
synthesis
of
inflammatory
cytokines.






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