Immuno (Innate)

Question 1

What are sentinel cells?

Answer 1

-pro inflammatory chemokines, lipid mediators, cytokines & antimicrobial
-dendritic cells, mast cells, macrophages

Question 2

What are the inflammatory mediators? (Chemokines & cytokines)

Answer 2

-IL-1B, IL-6, TNF-a
-from macrophages
-leukocyte & endothelial activation = systemic reaction

Question 3

What are the inflammatory mediators? (Plasma proteins)

Answer 3

-C3a = mast cell degranulation, smooth muscle contraction
-C5a = same as C3a + leukocyte chemotaxis, vascular permeability
-from complement activation

Question 4

What are the inflammatory mediators? (Vasoactive amines)

Answer 4

-histamine & serotonin
-from mast cell degranulation
-vascular permeability & smooth muscle contraction

Question 5

Describe mast cells role in inflammation.

Answer 5

-histamine & serotonin
-vasoactive (vasodilation) = vascular permeability increase
-> more leukocytes

Question 6

Describe physiological effects of inflammation.

Answer 6

-hypothalamus = fever, anorexia, sleepiness, depression
-liver = increased acute phase proteins (iron sequestration)
-bone marrow = increased white cell production
-IL1, IL6, TNF-a, HMGB1

Question 7

Describe pathological effects of inflammation.

Answer 7

-fever, acidosis, hypotension, complement activation, intravascular coagulation, endothelial damage
-multiple organ system failure
-death
-SIRS
-IL1, IL6, CCL8, TNF-a, NO

Question 8

Describe leukocyte extravasation.

Answer 8

-macrophages & dendritic cells = cytokines
-activate endothelial cells = express selectins & ligands for integrins -> secrete chemokines
>selectins = rolling
>integrins = adhesion
>chemokines = migration

Question 9

Describe leukocyte kinetics during inflammation.

Answer 9

Days -> weeks
1. Neutrophils dominate during acute inflammation
2. Monocytes/macrophages dominate later
3. Lymphocytes present once adaptive immune system is

Question 10

Describe phagocytosis.

Answer 10

-neutrophils & macrophages
-cytokine production
-present antigens

Question 11

What are the steps of phagocytosis.

Answer 11

1. Recognition of microbe
2. Endocytosis
3. Phagosome maturation
4. Fusion of phagosome & lysosome
5. Killing of bacteria inside phagolysosome

Question 12

Describe intracellular killing mechanisms (oxidative).

Answer 12

-oxygen & glucose
-ROS & RNS
-toxic

Question 13

Describe intracellular killing mechanisms (non-oxidative).

Answer 13

-cationic proteins = damage bacteria cell wall
-lysozyme = damage mucopeptides in bacterial cell wall
-lactoferrin = sequestrates iron & inhibit bacterial growth
-proteolytic & hydrolytic enzymes = digest killed bacteria

Question 14

Describe extracellular killing by NETs.

Answer 14

-neutrophil extracellular traps
-increase inflammatory stimulus
-extrude strands of nuclear DNA & proteins into ECF
-traps & kills microbes

Question 15

Describe the alternative pathway.

Answer 15

-complement proteins activated on microbial surfaces (present on host cells, not microbes)

Question 16

Describe the lectin pathway.

Answer 16

-activated when carbohydrate-binding plasma protein, mannose-binding lectin (MBL) binds to terminal mannose residues on surface of glycoproteins

Question 17

Describe the classical pathway.

Answer 17

-activated by antibodies that bind to microbes/antigens

Question 18

Describe the membrane attack complex (MAC).

Answer 18

-breaches cell membrane of microbe = allows water to rush into cell
-destruction by osmotic lysis
-C5b67 -> C8 unfolds hydrophobic region -> C9 creates cylindrical pore -> MAC -> osmotic lysis

Question 19

Describe Type I interferons.

Answer 19

-produced by virus infected cells
-nonspecific response to viral infection
-IFN-a & IFN-B = inhibit viral replication (protein synthesis, RNA, gene expression, & virion assembly) & induce antiviral state

Question 20

Describe NK cells.

Answer 20

A. Kill cells that are infected
-healthy host cells express MHC which are recognized by inhibitory receptors (engaged = NK inactive)
B. Secrete IFN-Y = activates macrophages (kills phagocytosed microbes)
-NK cells activated by infected or mutated cells where ligand for activating receptors are expressed & class I MHC expression is reduced/inhibited (not engaged = NK active)