L2-Cells of the Immune System

Question 1

What are HSCs?

Answer 1

Hematopoietic Stem cells: multipotent stem cells that produce differentiated blood cell types

Question 2

Where do you find HSCs in the bone marrow?

Answer 2

Niche of osteoblasts or sinusoidal epithelial cells

Question 3

What do HSCs require to retain self renewal?

Answer 3

Surrounded by a niche to receive growth factors and regulatory molecules

Question 4

What allows HSCs to home to the bone marrow and their niches?

Answer 4

Chemical signals in the niches

Question 5

What do stromal cells do?

Answer 5

Located within niches and provides factors needed for HSC maintenance as well as activation and differentiation

Question 6

Where do HSCs leave the bone marrow through?

Answer 6

Sinusoids and circulate throughout body before homing back to bone marrow

Question 7

What are the 2 pathways that an HSC differeniate to?

Answer 7

Common Myeloid Progenitor

Common Lymphoid Progenitor

Question 8

What do common lymphoid progenitors differentiate into?

Answer 8

NK Cells
T lymphocytes
B lymphocytes

Question 9

What do common myeloid progenitors differentiate into?

Answer 9

Thrombocytes
Erythrocytes
Mast Cells
Basophils
NeutrophilsEosinophils
Macrophages
Dendritic cells

Question 10

What induces HSC differentiation into common myeloid progenitors?

Answer 10

IL-3 GM-CSF

Question 11

What induces HSC differentiation into common lymphoid progenitors?

Answer 11

IL-7

Question 12

What induces common lymphoid progenitors to become T or B lymphocytes?

Answer 12

T: IL-2
B: IL-3

Question 13

What induces the common myeloid progenitor to become Basophils, Neutrophils, Eosinophils, Monocytes?

Answer 13

Basophil: IL-4
Neutrophils: G-CSF
Eosinophil: IL-5
Monocyte: GM-CSF, M-CSF

Question 14

What induces the common myeloid progenitor to become Basophils, Neutrophils, Eosinophils, Monocytes?

Answer 14

Basophil: IL-4
Neutrophils: G-CSF
Eosinophil: IL-5
Monocyte: GM-CSF, M-CSF

Question 15

What is the sequence of lymphocytes as they circulate between lymph and blood?

Answer 15

Enter lymph node from blood -> scan APCs for antigens -> stimulated -> activated -> go back to lymphatics -> back to blood via thoracic duct -> site of infection/inflammation

Question 16

What are the lymphoid depots?

Answer 16

Lymph nodes
Peyer’s patch: mucosal lymphoid tissue
Spleen
Tonsils/Adenoids

Question 17

What is the sequence of lymphocytes as they circulate between lymph and blood?

Answer 17

Enter lymph node from blood -> scan APCs for antigens -> stimulated -> activated -> go back to lymphatics -> back to blood via thoracic duct ->left subclavian v. -> site of infection/inflammation

Question 18

What are the lymphoid depots?

Answer 18

Lymph nodes
Peyer’s patch: mucosal lymphoid tissue
Spleen
Tonsils/Adenoids

Question 19

How do lymphocytes home into the area of infection once it gets into the blood?

Answer 19

chemokines and inflammatory responses will attract it to the site of infection

Question 20

What happens at the end of an infection by lymphocytes?

Answer 20

some will survive to become memory cells that will mount an efficient response to same pathogen i the future

Question 21

Are neutrophile multilobe or single lobed?

Answer 21

multilobed

Question 22

What kind of cytoplasmic granules do neutrophils have?

Answer 22

Neither basic nor acidic -> stain light pink (neutral)

Question 23

What is the most abundant WBC in blood?

Answer 23

Neutrophils

Question 24

What are primary granules in neutrophils?

Answer 24

Directly toxic or enzymes that cleave to make toxic

Question 25

What are secondary granules in Neutrophils?

Answer 25

REspiratory burst that creates free radicals to kill

Question 26

What are the methods with which neutrophils go about extracellular killing?

Answer 26

Phagocytosis Degranulation NETs:

Question 27

What is NETs?

Answer 27

Neutrophil Extracellular Traps: Neutrophiil takes pieces of its DNA/nuclear elements and mushes them with granules and tosses it out -> bactera gets caught and immobilized to decrease spread and help with phagocytosis

Question 28

What does dead neutrophils produce?

Answer 28

pus

Question 29

What happens during phagocytosis?

Answer 29

Engulfed/internalized -> form phagosome -> phagosome is acidified -> granules with lysosome fuses with phagosome -> form phagolysosome -> enzymes and antimicrobial substances released -> pathogen destroyed

Question 30

What happens during phagocytosis?

Answer 30

Engulfed/internalized -> form phagosome -> phagosome is acidified -> granules with lysosome fuses with phagosome -> form phagolysosome -> enzymes and antimicrobial substances released -> pathogen destroyed

Question 31

Where do macrophages derive from?

Answer 31

Circulating monocytes

Question 32

What are the primary roles for macrophages?

Answer 32

Phagocytosis/Intracellular killing Antigen presentation Scavenge dead cells and debris

Question 33

What do macrophages do to help adaptive system?

Answer 33

Send out chemical signals for immune system activation and WBC recruitment to bring in neutrophils and adaptive cells

Question 34

What do tissue macrophages secrete in the immune responsne?

Answer 34

TNF-a IL-1B IL-6

Question 35

How do macrophages recognize pathogens?

Answer 35

Dont know specific bacteria but can recognize foreign pathogens via PRRs (TLR-4)

Question 36

How do macrophages recognize pathogens?

Answer 36

Dont know specific bacteria but can recognize foreign pathogens via PRRs (TLR-4)

Question 37

What are the functions of dendritic cells?

Answer 37

Uptake antigens and present to stimulate adaptive system

Question 38

what purpose do the long finger like processes of DCs serve?

Answer 38

increases surface area for antigen display

Question 39

Where do DCs go to lymph nodes to present antigen?

Answer 39

Lymph nodes where it can interface with T and B cells

Question 40

What do eosinophils do?

Answer 40

Kill antibody coated parasites that are too big for phagocytosis

Question 41

What kind of granules do eosinophils have?

Answer 41

Very basic; Stains bright pink

Question 42

What are the components of Eosinophils to kill?

Answer 42

Major Basic Protein: toxic to both parasites and tissues; triggers mast cell histamine release Eosinophil Collegenase: remodel connective tissue m atrix Leukotrienes: SMooth muscle contraction, inc vascular permeability and mucus secretions Eosinophil derived neurotoxin

Question 43

Where are eosinophils found?

Answer 43

subepithelial connective tissue

Question 44

What are the downsides to eosinophils?

Answer 44

damages healthy surrounding tissue

Question 45

What are the downsides to eosinophils?

Answer 45

damages healthy surrounding tissue

Question 46

What are mast cells?

Answer 46

Large mononuclear cells with dark basophilic granules with acidic histamine

Question 47

What is the function of mast cells?

Answer 47

allow WBCs to enter site of infection by degranulating vasoactive substances to increase blood flow, inc vascular permeability

Question 48

What does smooth muscle cell constriction lead to in the vasculature?

Answer 48

Allows separation of vasculature to allow cells to get in/out as well as antibodies due to vasodilation

Question 49

What can inappropriate mast cell activation lead to?

Answer 49

Local: Urticaria Systemic: Activated mast cells due to allergen in blood stream or rapidly absorbed in gut

Question 50

What do basophils do?

Answer 50

Help with parasitic infection and allergic responses | HAs dark basophilic granules with histamine and heparin

Question 51

What are the lymphoid WBCs?

Answer 51

NK cells T cells B cells

Question 52

What are NK cells?

Answer 52

Natural Killer cells that target virally infected cells or tumor cells and kill by degranulation and lysis

Question 53

Are NK cells part of adaptive or innate?

Answer 53

INNATE: THeir receptors are invariant and do not rearrange and become specific for one antigen

Question 54

How do NK cells recognize their targets?

Answer 54

Can recognize when cells don't look normal and will attack them to cause apoptosis as adaptive immune system gears up

Question 55

WHat do activated B cells become and do?

Answer 55

Plasma Cells - secrete antibodies against antigens

Question 56

What role do T cells play?

Answer 56

Comanders in chief; Can differentiate into cytotoxic T cells or helper T cells dpending ont he antigen/infection detected