Immunology 2

Question 1

What is the first line of defence for the body?

Answer 1

Physical barriers:
Skin - turn over rate means microorganisms are shed; low pH; sweat glands secrete protective oils
Mucous - traps foreign particle in mucociliary escalator; has antimicrobial properties
Commensal bacteria - on skin and in GI tract compete with pathogens

Question 2

What is the immune system?

Answer 2

Network of specialised cells, tissues and soluble factors cooperating to kill disease-causing pathogens and cancer cells

Question 3

What are the major components of the immune system?

Answer 3

Wbcs

Soluble/humoral factors

Question 4

What are the wbcs?

Answer 4

Phagocytes (neutrophils, monocytes/macrophages, dendritic cells)

Lymphocytes (T and B cells, Natural Killer cells)

Mast cells
Eosinophils
Basophils

Question 5

What are soluble/humoral factors?

Answer 5

Antibodies
Complement System proteins
Cytokines (involved with cell signalling)
Acute Phase Proteins

Question 6

What are antibodies? What do they do?

Answer 6

Immunoglobins (glycoproteins) produced in response to an antigen and bind to it

Provide defence against extracellular pathogens and toxins

Question 7

What is an antigen?

Answer 7

Substance that can stimulate immune response

Have an EPITOPE, that is complementary to the antibody

Question 8

What is the complement system? What is the function?

Answer 8

Family of around 30 different proteins produced in the LIVER.

Helps/complements ability of antibodies/phagocytes to clear pathogens

Question 9

How do complement proteins work?

Answer 9

Enter infected/inflamed tissue and activated
Can enzymatically cleave and activate other downstream complement proteins in a biological CASCADE (capacity for HUGE AMPLIFICATION of response)

Question 10

What are cytokines and when are they produced?

Answer 10

Small proteins involved with cell signalling and have a short half-life

Produced in response to infection, inflammation, tissue damage

Question 11

Give examples of cytokines and what they do

Answer 11

Interferons - anti-viral activity

Tumour Necrosis Factor α (TNFα) - pro-inflammatory cytokine

Chemokines - control and direct cell migration via chemotaxis

Interleukins - various functions

Question 12

Where do cells of the immune system originate from?

Answer 12

From haematopoietic stem cells

Question 13

What are the phagocytic cells and what do they do?

Answer 13

Monocytes, macrophages (in tissue), neutrophils

Ingest and kill bacteria/fungi (phagocytosis)

Ingest and clear debris, like dead/dying apoptotic cells and immune complexes (antigen/antibody complexes)

Sources of cytokines that regulate acute inflammatory responses

Question 14

What do monocytes do?

Answer 14

Circulate in blood (5% of all wbcs)

Migrate into peripheral tissues and differentiate into MACROPHAGES

Question 15

What are the macrophages?

Answer 15

Long-lived tissue resident phagocytes:
Kupffer cells
Alveolar macrophages
Mesangial cells
Microglial cells

Question 16

What do macrophages do, in addition to phagocytosis?

Answer 16

Limit inflammation
Involved in tissue repair and wound healing
Involved in antigen presentation

Question 17

What are neutrophils? Where do they go once out of blood?

Answer 17

AKA polymorphnuclear cells (PMNS). Short-lived cells (half-life of 6 hrs in blood)

Phagocytic cells circulating in blood (50-70% of wbcs)

Rapidly recruited into inflamed, damaged and infected tissues

Question 18

What are dendritic cells?

Answer 18

Antigen presenting cells (enable antigen recognition by T cells)

Question 19

How do dendritic cells work?

Answer 19

Present in peripheral tissues in “immature” state
Phagocytose antigens
Mature and migrate into secondary lymphoid tissues (play key role in antigen presentation)

Question 20

Dendritic cells, macrophages and neutrophils in order of killing ability?

Answer 20

Neutrophils
Macrophages
Dendritic cells

Question 21

Dendritic cells, macrophages and neutrophils in order of ability to present antigens?

Answer 21

Dendritic cells
Macrophages
Neutrophils

Question 22

What are mast cells? Function?

Answer 22

Reside in tissues and protect mucosal surfaces

Question 23

What do basophils and eosinophils do?

Answer 23

Circulate in blood until recruitment to infected sites by inflammatory signals

Question 24

What do mast cells, basophils and eosinophils have in common?

Answer 24

Highly granular cells and are the defence system against large pathogens that cannot be phagocytosed, like parasitic worms

Release chemical, like histamines , heparin and cytokines - involved with acute inflammation

Key role in mediating allergic response (overactive immune response to harmless substances)

Anti-histamines

Question 25

What are Natural Killer (NK) cells? Function?

Answer 25

Large granular lymphocytes that release lytic granules to kills tumour cells and virus-infected cells Can also kills antibody-bound cells/pathogens

Question 26

What do T and B cells have in common?

Answer 26

Mature cells constantly circulating blood, lymph and secondary lymphoid tissues Inactive until meeting with a pathogen/antigen Some are very long-lived (memory T and B cells)

Question 27

What do B cells do?

Answer 27

Involved with HUMORAL immune response | Produce/secrete ANTIBODIES to defend against EXTRACELLULAR pathogens

Question 28

What do T cells do?

Answer 28

Defend against INTRACELLULAR pathogens (viruses, etc)

Question 29

Types of T cells?

Answer 29

Helper T cells - regulators of immune system | Cytotoxic T cells - kill virally infected cells

Question 30

What is the basis of immunological memory?

Answer 30

Once ADAPTIVE immune system has recognised/responded to a specific antigen, it will exhibit LIFE-LONG immunity to this antigen Mediated by MEMORY T and B cells

Question 31

What are the primary lymphoid tissues?

Answer 31

Where wbcs form and mature: Red bone marrow Thymus gland

Question 32

What are the secondary lymphoid tissues?

Answer 32

``` Where lymphocytes are activated: Lymph nodes Tonsils Spleen MALT (Mucosal Associated Lymphoid Tissues) ``` Sites where adaptive immune responses are initiates (contain T and B cells, and dendritic cells)

Question 33

What are the two types of immune system?

Answer 33

Innate immune system | Adaptive immune system

Question 34

What characterises the innate immune system?

Answer 34

RAPID response | Same GENERAL response to many different pathogens

Question 35

What characterises the adaptive immune system?

Answer 35

SLOW response Response is UNIQUE to each individual pathogen Mediated by T and B cells Responsible for IMMUNOLOGICAL MEMORY

Question 36

What is the lymphatic system?

Answer 36

System of vessels that drain tissue fluid (lymph) LYMPH NODES are regularly positioned along lymphatic vessels - trap pathogens/antigens in lymph

Question 37

What is lymphoedema?

Answer 37

AKA lymphatic obstsruction Localised fluid retention and tissue swelling due to compromised lymphatic system (normally interstitial fluid in returned to bloodstream via thoracic duct)

Question 38

What are the causes of lymphoedema?

Answer 38

Inherited Cancer Parasitic infections Tissues with lymphoedema are at risk of infection