Immune team

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Immune team
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Cell injury can result from
Hypoxia Physical chemical agents .
Microbial agents. (defective immunity).
Immune reactions. (abnormal responses)
Genetic factors . Nutritional imbalances.
These Various stimuli cause cell injury
induce a complex vascular
cellular response called
Inflammation
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Inflammation
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There are 2 types of infections - 1 sub
clinical infections (MCQ) we have it all the
time so it is common , it have no symptoms or
signs because it get controled before produce
symptoms 2 clinical infections they are quite
rare , they produce symptoms and usually indicate
failure to control infections
All defense mechanisms are collectively
called immunity
Immunity is divided into (MCQ)
Adaptive ( acquired ) Specific
Natural ( innate ) is non-specific
1 the to divisions are well integrated 2 the
2 division are connected through a cytokine
network ( inflammatory pathway )
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The immune system has to main functions
Recoginition 1- the immune system
is able to recognize and distinguish one pathogen
from another through chemical differences 2- and
able to discriminate between foreign molecules
and the body own cells
Response The response is
divided to
Memory response this mechanism usually accure
in acquired immunity , later exposure to the same
foreign body induce a response that call and
recrutis a special unit of the big army ( maybe
Marine ) that have an effecte on that
organism , so this mechanism is specific and
contain memory for different pathogens
Effector response this mechanism usually
accure in natural immunity , once a foreign body
has been recognized , the immune system will call
and recrutis all his warriors army ( effecror
cells ) to defeat that organism
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Differences between the natural and acquired
immunity
MCQ
Natural immunity
acquired immunity Very limited
diverse cell surface Cell surface
receptors receptors (Fewer than
100 receptor) Non specific
specific No memory retention
there is immunologic Because the
cells half memory Life
is short
Mechanism of recognition of microb Effecror
mechanism ( response ) Immunologic memory
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Natural immunity serve as
A warning signal that a microbe is
invading the tissues

• A critical early defense , ( mobilized
  within minutes after invasion by microbes )

• Stimulate influence adaptive
  immunity ( secrete cytokines
  activate cells )

A progressing infection that pass natural defense
mechanisms will be stoped by adaptive ( antibody
mediated response called humoral immunity ) if it
was extracellular infection , but if it was
intracellular infection it will be stoped by
adaptive ( cell mediated response called cell
mediated immunity )
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Defense mechanisms of natural immunity -
? anatomic barriers ? 1- skin is a
mechanical barrier that work as a shaled
preventing microbes from entering It has an
acidic enviroment that retards grouth of
microbes 2- The mucus membranes Normal flora
compete ( fight ) with microbes for attachment
sites and nutrients 3- Mucus secreted by goblet
cells entraps foreign bodies microbes 4- Cilia
propel microorganisms out of the body by coughing
and sneezing ( smooking cause damage to cilia so
smookers are expoused to lung infections )
disruptions of anatomic barriers 1- burns , cut
wounds , skin diseases (eczema) 2- Aseptic
techniques ( taking a blood sample or I / V
catheters ) 3- Disruption of the mucus membrane (
oral cavity ) by dental procedures
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Physiologic barrier ? ? Temperature Normal
body temperature inhibits growth of some
pathogens ( fever inhibits growth of
pathogens) Low pH Acidity of stomach contents
kills most ingested microbes Chemical mediators
Lysozyme cleaves bacterial cell wall , and
Collectins wich stick to the pathogen so it get
phagocytosed Natural antibiotics like defensins
, cryptidins in stomach
MCQ
Physiologic functions Coughing , sneezing ,
voiding urine , tears , saliva in oral cavity
etc when Physiologic functions are absent like in
( Inability to cough or Urine retention )
predispose to infections is likely to be
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Circulating effector cells
1- Neutrophils ( most important ) 2-
Macrophages 3- Natural killer (NK) cells (viral
immunity) 4- Eosinophils (parasitic and allergic
immunity) 5- Mast cells (mediator of inflammation
) 6- Platelets ( coagulation and mediator of
inflammation) 7- B-1 cells found in fetus
neonates respond to bacterial antigens (
polyssacharides )
The Phagocytic cells have two hands on its
surface that use them to shake the two hands
found on pathogen surface so it can recognize
it The first hand of Phagocytic cells called Toll
- like receptor (TLRs) that shake
lipopolysaccaride (LPS) hand found on pathogen
surface (gram negative bacteria ) The second hand
of Phagocytic cells called Pattern-recognition
receptors (PRR) that shake Pathogen - associated
molecular patterns hand (PAMPs ) found on
pathogen
MCQ
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Neutrophils
Mediate the early phase of inflammation They are
recruited to the site of infections by a process
called chemotaxis
MCQ
comprise ( 60 -70 percent) Of the WBC Short -
lived cells work in extra - cellular
infections Contain enzymes Perform killing by
1- Oxygen - dependent mechanisms 2- Oxygen -
independent mechanisms It is a polymorphonuclear
cell
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Chemotaxis of phagocytic cells involve the
following steps 1- Rolling ( loose adherence )
to endothelium 2- Activation of cells 3- Stable
adherence to endothelium 4- Transmigration into
tissue spaces
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Mononuclear cells
Monocytes Macrophages Long - lived
cells Contain enzymes secrete many cytokines
work in intra-cellular infections Professional
phagocytic cells Antigen presenting cells
important in both natural adaptive immunity
MCQ
Circulating monocytes enter tissues become
resident macrophages , e.g of tissues 1- Sub -
epithelial connective tissue 2- Interstitia of
organs 3- Vascular sinusoids of the liver
spleen 4- Lymph nodes
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Macrophages are strategically located at sites
where Microbes enter the tissues They recognize
microbes first by their receptors (PRR ) Become
activated ,secrete cytokines and attract
Neutrophils
Macrophages are activated by
Bacterial products.
LPS. (gram neg. bacteria)
Bacterial DNA
MCQ
Secrete cytokines, attract neutrophils
Induce local inflammation.
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Macrophages produce many cytokines
MCQ
1. IL-1.
2. TNF
3. IL-6 4. IL-8
5. IL-12
Act on various tissues cells .
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macrophges perform multiple functions
1. Induce local inflammation. 2.
Perform phagocytosis. 3. Activate
coagulation . 4. Enhance antigen
presentation. 5. Initiate tissue
repair .
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Functions of macrophages
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Mechanism of intracellular killing by phagocytic
cells
1- Lysosomal enzymes 2- Production of reactive
oxygen intermediates 3- Production of nitric
oxide 4- circulating effecter proteins
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Natural killer cells
A class of larg granular cytotoxic lymphocytes
that do not have T or B cell receptors They are
antibody independent killers of tumors cells
and also participate in antibody dependent cell
mediated cytotoxicity
NK-cells are activated by
IL-12 and IL-15 Which are Produced by macrophages
Functions of NK cell 1- anti - viral
activity 2- anti tumor activity
MCQ
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Circulating effector proteins
1 - The complement proteins 2 - Mannose- binding
lectin 3 - C reactive proteins 4 - Coagulation
factors 5 - Cytokines
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The complement proteins
The complement system is a biochemical cascad
thats help to clear pathogens from the body it
consists of a number of small proteins found in
the blood and synthesized by the liver Normaly
they are inactive zymogens
MCQ
Activation of the complement system lead to
initiation of important effects which include
1- Release of chemotactic factors (C3a and C5a
) 2- Opsonisation of microbes (C3b ) 3- Lysis of
target cells (C8 C9 )
MCQ
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The complement proteins
The complement system is activated by 3 pathways
1 - classical pathway , require antigen -
antibody interaction 2 - alternative pathway ,
activated by bacterial products (LPS ,DNA ) 3
- lectin pathway , activated by mannan-binding
lectin
MCQ
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MEMBRANE ATTACK COMPLEX
C
C
C 9
C 9
C 9
C 9
C 9
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Cytokines of natural immunity
1- interferons ( anti - viral ) 2 IL-1 , TNF
and Chemokines ( mediate inflamation ) 3 IL-12
and IL-15 ( NK cells ) 4 interferon gamma (
act on macrophages ) 5 IL-6 ( act on bone
marrow ) 6 IL-10 and TGF-B ( limit local
inflammation )
MCQ
MCQ
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Other functions of Cytokines
The Cytokines IL-1 and IL-6 and TNF-alpha
coordinate body responses to infections by acting
on 1 liver , they induce the synthesis of
acute phase proteins 2 bone marrow , by
stimulating the mobilization of neutrophils 3
Hypothalamus , they induce it to increase body
temperature (induce fever ) 4 - Fat muscle , to
supply proteins energy 5 - T and B Lymphocytes
, to become activated and produce adaptive immune
responses
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Summary .
1. Natural Immunity is the first
line of defense.
2. It influence stimulate subsequent
adaptive immune
responses . 3. The immune response is
a Protective.
Sub clinical .
Localized reaction
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MCQ
5 - All are fearures of NK cells EXCEPT
a)phagocytic. b)anti-tumor activity. c)stimulate
d by activity. c)stimulated by IL-12. d)activated
by interferons. e)anti-viral activity
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MCQ
6 - Regarding cytokines all of the following are
true EXCEPT a) they are low MW proteins. b)
they act with surface receptors. c) are long
acting mediators. d) regulate inflammation
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MCQ
7 - Regarding CD molecules a) CD3 is found on
all B calls,not T cells. b) CD1 is found on
mature T cells. c) CD19CD20 are found on T
cells. d) CD4 is called cytotoxic. e) CD56 found
on NK cells
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MCQ
8 - All are features of complement system EXCEPT
a) lysis of damaged cells. b) opsonization of
microbes. c) chemoattractants for neutrophils. d)
participates in inflammation. e) inhibits
cytokines