Module 4: Innate immunity,
inflammation & adaptive immunity Innate immunity
1: Innate Immunity What makes up innate immunity?
Surface barriers
1. Summarise the characteristics of the Cells
innate immune system Antimicrobial peptides & proteins
2. Describe the physical barriers of the
innate immune system Responses of the innate immune system
3. Describe the cellular components of the Inflammation
innate immune response Fever
4. Understand the roles of the immune cells
involved in components of the innate
immune response
Immune System – Introduction ① Physical Barriers of Innate Immunity ②
Function: provides defence against infectious Skin
disease caused by microorganisms
Innate immunity: non-specific
Adaptive immunity: specific
1st line of defence
Intact skin barrier
Epidermis
Keratin & Keratinases
2nd line of defence Dermis
Sebaceous glands produce sebum –
lowers pH
Sweat – high salt
Both inhibits growth of some microorganisms
3rd line of defence
Mucous membranes
Function: Lines inner surfaces of the body
that open to the exterior
E.g., Oral cavity, respiratory tract, digestive
tract, urinary tract & reproductive tract.
Fast dividing to replace damaged cells
Epithelial cells and goblet cells (produce
mucous)
• BM1011 TERM Property TOPIC TITLE à subtopic ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ↓ ↑ ∴ ≈ 💡Mnemonic
,Mucous forms a layer over the surface to provide Physical barriers (skin, mucous membranes and
protection (mucinases) secretions)
Stomach – protects epithelium from 4. What are 5 characteristics of the innate
stomach acid immune system?
Respiratory – traps microbes and 1. Non-specific (always the same regardless of
pollutants the microorganism)
Coughing & sneezing reflexes are the 2. Simple form of immunity, no memory
bodies method of removing debris & 3. Functional and available at birth
microorganism trapped in the mucous 4. Responds quickly
5. Divided into physical barriers & non-specific
Intestine – prevents attachment of cellular defences (phagocytes, natural killer
pathogenic microorganisms cells, inflammation, antimicrobial proteins &
fever)
Secretions
Skin & mucous membranes also produce Cellular components of the innate immune
protective chemicals (antimicrobial chemicals) response ③
Role of the cellular components & processes
of the innate immune system
Questions Functions of the cellular components:
Recognise harmful microorganisms
1. What are the bodies three lines of
Identify parts of invading microorganisms
defence against infectious disease?
that are not part of the normal human cells
Surface barriers, internal defences & adaptive
(by proteins on surface, cell wall structure
defences
etc.)
2. How is the innate immune system
Types of cells in whole blood
different from the adaptive immune
Red blood cells (RBC, erythrocytes):
system?
contain haemoglobin that carries O2 to
The innate immune system is different from the
cells
adaptive immune system in the following ways:
Platelets: function in
Already present and function at birth
clotting
Innate system doesn’t have memory
Innate system is faster acting
White blood cells (WBC,
leukocytes): function in
3. What is the first line of defence against
the immune response
infectious disease?
• BM1011 TERM Property TOPIC TITLE à subtopic ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ↓ ↑ ∴ ≈ 💡Mnemonic
,Types of leukocytes Engulf pathogens & dead cell remains
Wear pieces of P’s & DCR’s on their cell
membrane after engulfing & digesting
Antigen presentation: when cells wear
pieces of the P or DCR’s to tell other
immune system cells what to look for. This is
how memory is created (antigen
presentation + interaction)
Interact with lymphocytes = adaptive
Roles of the specific immune cells ④ immunity
Phagocytes Question
Phagocytes: also, a type of WBC ∴ What is the difference between macrophages
Respond to pathogens that breach the & neutrophils?
skin/mucous membrane.
Attracted to the site of infection by Macrophages present the antigen and interact
chemicals (chemo-attractants) given off with lymphocytes to allow the generation of
by dying cells & by invading cells too memory of the invading microorganisms &
formation of specific immune responses.
2 types of phagocytes Therefore, they have a role in adaptive immunity
1. Neutrophils (bacteria & Phagocytosis
fungi)
Arrive first @ site of
infection/damage
Engulf pathogens & dead cell remains
Release chemicals that kill nearby
bacteria & attract other phagocytes
Short-lived
Chemotaxis: the movement of other cells as
a result of released chemicals. Can be
positive (toward the chemical) or negative
(away)
Lysosome inside the
phagocyte adheres
2. Monocytes/macrophages (bacteria & to the foreign
protozoa) particle to ingest it
Monocytes circulate in the
blood in an inactivated form
& differentiate into macrophages (active
component)
Arrive second after neutrophils @ site
• BM1011 TERM Property TOPIC TITLE à subtopic ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ↓ ↑ ∴ ≈ 💡Mnemonic
, Abscess: a pocket of enclosed/confined pus
ensuring it does not spread elsewhere in the
body.
Microbial evasion of phagocytosis
1. Inhibiting chemotaxis
Phagocytosis Summary Bordetella pertussis (whooping cough) – releases
1. Chemotaxis substance to block
Phagocyte detects chemicals released by a chemotaxis
foreign intruder (e.g., bacteria) and
injured cells. 2. Block adherence
Streptococcus
Phagocyte moves up the concentration pneumoniae (strep throat)
gradient (positive chemotaxis) towards – forms a polysaccharide
intruder layer/capsule around the
microbe
2. Adherence
Phagocyte adheres to the foreign cell & 3-4 Escape ingestion & Block digestion
engulfs it in a vacuole by an infolding of a. Exit phagosome & create own vacuole
the cell membrane Mycobacterium leprae & Toxoplasma gondii
3. Ingestion b. Block phagosome-
Lysosomes fuse with the vacuole & lysosome fusion
release their contents into it. Mycobacterium tuberculosis &
Legionella
Lysosome: organelle rich in digestive
enzymes & are found in phagocytes c. Block digestive
cytoplasm enzymes
Staph aureus & Leishmania
4. Digestion/destruction
The bacterium is digested by the enzymes in the
lysosome
Phagocytes & Pus
Pus forms @ site of inflammation during
infection
Indicates bacterial infection.
Natural Killer Cells
Pus is composed of:
Dead phagocytes (mostly neutrophils as Natural killer cells:
they are short lived) Innate lymphoid cells
Destroyed bacteria. Non-specific
Dead host cells
• BM1011 TERM Property TOPIC TITLE à subtopic ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ↓ ↑ ∴ ≈ 💡Mnemonic
inflammation & adaptive immunity Innate immunity
1: Innate Immunity What makes up innate immunity?
Surface barriers
1. Summarise the characteristics of the Cells
innate immune system Antimicrobial peptides & proteins
2. Describe the physical barriers of the
innate immune system Responses of the innate immune system
3. Describe the cellular components of the Inflammation
innate immune response Fever
4. Understand the roles of the immune cells
involved in components of the innate
immune response
Immune System – Introduction ① Physical Barriers of Innate Immunity ②
Function: provides defence against infectious Skin
disease caused by microorganisms
Innate immunity: non-specific
Adaptive immunity: specific
1st line of defence
Intact skin barrier
Epidermis
Keratin & Keratinases
2nd line of defence Dermis
Sebaceous glands produce sebum –
lowers pH
Sweat – high salt
Both inhibits growth of some microorganisms
3rd line of defence
Mucous membranes
Function: Lines inner surfaces of the body
that open to the exterior
E.g., Oral cavity, respiratory tract, digestive
tract, urinary tract & reproductive tract.
Fast dividing to replace damaged cells
Epithelial cells and goblet cells (produce
mucous)
• BM1011 TERM Property TOPIC TITLE à subtopic ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ↓ ↑ ∴ ≈ 💡Mnemonic
,Mucous forms a layer over the surface to provide Physical barriers (skin, mucous membranes and
protection (mucinases) secretions)
Stomach – protects epithelium from 4. What are 5 characteristics of the innate
stomach acid immune system?
Respiratory – traps microbes and 1. Non-specific (always the same regardless of
pollutants the microorganism)
Coughing & sneezing reflexes are the 2. Simple form of immunity, no memory
bodies method of removing debris & 3. Functional and available at birth
microorganism trapped in the mucous 4. Responds quickly
5. Divided into physical barriers & non-specific
Intestine – prevents attachment of cellular defences (phagocytes, natural killer
pathogenic microorganisms cells, inflammation, antimicrobial proteins &
fever)
Secretions
Skin & mucous membranes also produce Cellular components of the innate immune
protective chemicals (antimicrobial chemicals) response ③
Role of the cellular components & processes
of the innate immune system
Questions Functions of the cellular components:
Recognise harmful microorganisms
1. What are the bodies three lines of
Identify parts of invading microorganisms
defence against infectious disease?
that are not part of the normal human cells
Surface barriers, internal defences & adaptive
(by proteins on surface, cell wall structure
defences
etc.)
2. How is the innate immune system
Types of cells in whole blood
different from the adaptive immune
Red blood cells (RBC, erythrocytes):
system?
contain haemoglobin that carries O2 to
The innate immune system is different from the
cells
adaptive immune system in the following ways:
Platelets: function in
Already present and function at birth
clotting
Innate system doesn’t have memory
Innate system is faster acting
White blood cells (WBC,
leukocytes): function in
3. What is the first line of defence against
the immune response
infectious disease?
• BM1011 TERM Property TOPIC TITLE à subtopic ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ↓ ↑ ∴ ≈ 💡Mnemonic
,Types of leukocytes Engulf pathogens & dead cell remains
Wear pieces of P’s & DCR’s on their cell
membrane after engulfing & digesting
Antigen presentation: when cells wear
pieces of the P or DCR’s to tell other
immune system cells what to look for. This is
how memory is created (antigen
presentation + interaction)
Interact with lymphocytes = adaptive
Roles of the specific immune cells ④ immunity
Phagocytes Question
Phagocytes: also, a type of WBC ∴ What is the difference between macrophages
Respond to pathogens that breach the & neutrophils?
skin/mucous membrane.
Attracted to the site of infection by Macrophages present the antigen and interact
chemicals (chemo-attractants) given off with lymphocytes to allow the generation of
by dying cells & by invading cells too memory of the invading microorganisms &
formation of specific immune responses.
2 types of phagocytes Therefore, they have a role in adaptive immunity
1. Neutrophils (bacteria & Phagocytosis
fungi)
Arrive first @ site of
infection/damage
Engulf pathogens & dead cell remains
Release chemicals that kill nearby
bacteria & attract other phagocytes
Short-lived
Chemotaxis: the movement of other cells as
a result of released chemicals. Can be
positive (toward the chemical) or negative
(away)
Lysosome inside the
phagocyte adheres
2. Monocytes/macrophages (bacteria & to the foreign
protozoa) particle to ingest it
Monocytes circulate in the
blood in an inactivated form
& differentiate into macrophages (active
component)
Arrive second after neutrophils @ site
• BM1011 TERM Property TOPIC TITLE à subtopic ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ↓ ↑ ∴ ≈ 💡Mnemonic
, Abscess: a pocket of enclosed/confined pus
ensuring it does not spread elsewhere in the
body.
Microbial evasion of phagocytosis
1. Inhibiting chemotaxis
Phagocytosis Summary Bordetella pertussis (whooping cough) – releases
1. Chemotaxis substance to block
Phagocyte detects chemicals released by a chemotaxis
foreign intruder (e.g., bacteria) and
injured cells. 2. Block adherence
Streptococcus
Phagocyte moves up the concentration pneumoniae (strep throat)
gradient (positive chemotaxis) towards – forms a polysaccharide
intruder layer/capsule around the
microbe
2. Adherence
Phagocyte adheres to the foreign cell & 3-4 Escape ingestion & Block digestion
engulfs it in a vacuole by an infolding of a. Exit phagosome & create own vacuole
the cell membrane Mycobacterium leprae & Toxoplasma gondii
3. Ingestion b. Block phagosome-
Lysosomes fuse with the vacuole & lysosome fusion
release their contents into it. Mycobacterium tuberculosis &
Legionella
Lysosome: organelle rich in digestive
enzymes & are found in phagocytes c. Block digestive
cytoplasm enzymes
Staph aureus & Leishmania
4. Digestion/destruction
The bacterium is digested by the enzymes in the
lysosome
Phagocytes & Pus
Pus forms @ site of inflammation during
infection
Indicates bacterial infection.
Natural Killer Cells
Pus is composed of:
Dead phagocytes (mostly neutrophils as Natural killer cells:
they are short lived) Innate lymphoid cells
Destroyed bacteria. Non-specific
Dead host cells
• BM1011 TERM Property TOPIC TITLE à subtopic ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ↓ ↑ ∴ ≈ 💡Mnemonic
