Innate immunity 2

Question 1

What are the possible effector responses of innate immune cells?

Answer 1

phagocytosis, degranulation, antigen presentation, mediator release

Question 2

What are mediators?

Answer 2

Soluble proteins or chemicals produced by immune cells in an immune response

Question 3

Where do immune cells in the oral mucosa come from?

Answer 3

Some are tissue resident even in health (release chemokines during infection), others arrive from circulation in response to signalling molecules

Question 4

Which is the main type of immune cell that is an early responder to infection?

Answer 4

Neutrophils

Question 5

What is neutrophil chemotaxis?

Answer 5

Neutrophils moving towards an increasing concentration of chemokines

Question 6

Which cytokine/chemokine is important for recruitment of immune cells?

Answer 6

CXCL8 (IL-8) - a type of chemokine and cytokine

Question 7

Diapedesis definition?

Answer 7

The migration of immune cells out of circulation into blood vessel walls (cellular migration)

Question 8

Which word is extravasation the old term for?

Answer 8

Diapedesis

Question 9

How does diapedesis occur?

Answer 9

Receptors and ligands on neutrophils and endothelial cells interact to enable neutrophils to move towards an increasing chemokine (CXCL8) concentration in the surrounding tissues.

Question 10

Which receptors are involved in diapedesis?

Answer 10

Selectins (e.g. E-selectins), Integrins (e.g. LFA-I), Immunoglobulin superfamily

Question 11

What is LFA-I?

Answer 11

Lymphocyte Function-associated Antigen 1 (an integrin receptor involved in diapedesis)

Question 12

What are granules?

Answer 12

Vesicles containing soluble mediators

Question 13

What mediators do granules contain?

Answer 13

Proteinases, Antimicrobials (e.g. AMPs, lactoferrin), Chemical mediators (e.g. histamine)

Question 14

Which immune cells undergo degranulation?

Answer 14

eosinophils, basophils, neutrophils, NK cells, mast cells (granulocytes, innate immune cells)

Question 15

Where is histamine released from?

Answer 15

Mast cells and Basophils when they degranulate

Question 16

What are the wide spread effects of histamine?

Answer 16

Vasodilation and increased vascular permeability (more leaky so more diapedesis), smooth muscle contraction, bronchoconstriction, neurotransmission (itching sensation in allergies)

Question 17

What process do neutrophils undergo?

Answer 17

NETosis which traps pathogens (as well as degranulation and phagocytosis)

Question 18

What is NETosis?

Answer 18

The release of proteins and chromatin (DNA) from neutrophils during degranulation to form extra-cellular fibril matrix (Neutrophil Extracellular Traps)

Question 19

Function of natural killer cells

Answer 19

recognise and kill abnormal cells (and invading microbes)

Question 20

Examples of abnormal cells killed by natural killer cells

Answer 20

cancer cells, host cells infected by virus

Question 21

What is ADCC?

Answer 21

Antibody-Dependent Cellular Cytotoxicity - B cells produce antibodies that bind to abnormal cells / microorganisms and tag them for apoptosis by NK cells and eosinophils

Question 22

How do NK cells cause apoptosis of abnormal cells?

Answer 22

NK cells release perforin (creates pores in abnormal cells) and granzymes (lyse cell)

Question 23

What is apoptosis?

Answer 23

Programmed cell death

Question 24

Function of eosinophils

Answer 24

Undergoes ADCC for destruction of microorganisms and is anti-parasitic (MBP)

Question 25

What is MBP?

Answer 25

Major Basic Protein - a potent antiparasitic enzyme toxin that drives cellular lysis

Question 26

What does ADCC rely on?

Answer 26

antibodies produced by B cells

Question 27

Which immune cells carry out phagocytosis?

Answer 27

Phagocytes (neutrophils, macrophages, dendritic cells)

Question 28

Overview of phagocytosis

Answer 28

degradation, antigen presentation, safe break down and dispose of apoptotic and necrotic cells

Question 29

Stages of phagocytosis

Answer 29

recognition, engulfment, phagosome formation, phagolysosome formation, cell digestion/degradation, exocytosis / antigen presentation

Question 30

Opsonization definition

Answer 30

tagging of cells for removal

Question 31

What are initiating factors of phagocytosis?

Answer 31

Antibodies / complement components bind to antigens (opsonization) which is detected by Pattern Recognition Receptors / Fc receptors on phagocytes

Question 32

Efferocytosis definition

Answer 32

removal of apoptotic or necrotic cells

Question 33

How is innate immunity linked to adaptive immunity?

Answer 33

Antigen presentation

Question 34

How does antigen presentation occur?

Answer 34

Antigens are presented to T cells via Major Histocompatibility Complex receptors (MHC) at the end of phagocytosis

Question 35

What is MHC?

Answer 35

Major Histocompatibility Complex - set of genes that present proteins within the host cell to T cells to initiate the adaptive immune response.

Question 36

What is MHC class I involved with?

Answer 36

MHCI presents endogenous proteins (viral, tumour cells) to T cells. (found on all nucleated cells)

Question 37

Which MHC class is present on all nucleated cells?

Answer 37

MHCI (so all cells can initiate immune response)

Question 38

What is MHC class II involved with?

Answer 38

MHCII presents exogenous proteins (post-phagocytosis / antigen presenting cells)

Question 39

Which cells detect MHCI?

Answer 39

CD8 (cytotoxic T cells)

Question 40

Which cells detect MHCII?

Answer 40

CD4 (T helper cells)

Question 41

What is the largest component of human blood?

Answer 41

Plasma (55%)

Question 42

Name the four enzymatic cascade systems in plasma

Answer 42

Complement, Kinins, Coagulation factors, Fibrinolytic system

Question 43

What are complement proteins?

Answer 43

a collection of soluble pro-inflammatory proteins present in circulation

Question 44

Where are complement proteins produced?

Answer 44

By immune cells and in the liver

Question 45

Function of complement proteins

Answer 45

Drive opsonization and inflammatory responses, forms membrane attack complexes which creates pores on microbial cells causing lysis.

Question 46

How are complement proteins pro-inflammatory?

Answer 46

Increase vascular permeability by increasing interstitial space, fluid leakage and diapedesis (so more immune cells migrate)

Question 47

Which complement proteins drive anaphylaxis?

Answer 47

C5a and C3a

Question 48

What are the complement proteins C5a and C3a called?

Answer 48

anaphylatoxins

Question 49

What are the 3 pathways of complement?

Answer 49

Classical pathway (antigen-antibody complexes), Lectin pathway (MBL-MASP complexes directed by microorganism), Alternative pathway (microbial components e.g. proteins, enzymes, virulence factors)

Question 50

How is the classical pathway for complement triggered?

Answer 50

Via antibody-antigen complexes or allergens

Question 51

How is the lectin pathway for complement triggered?

Answer 51

via MBL-MASP complexes directed by microorganism (mannan-binding lectin and MBL associated serine protease)

Question 52

How is the alternative pathway for complement triggered?

Answer 52

via microbial components e.g. proteins, enzymes, virulence factors. Also allergens

Question 53

Which complement pathways can allergens stimulate?

Answer 53

Classical and alternative pathway