Ch. 2 Cells of the Immune System

Question 1

What type of stem cell differentiates into all the blood cells needed by the body?

Answer 1

Hematopoietic stem cells

Question 2

Multipotent

Answer 2

multiple+ able; develop into multiple types of cells

Question 3

Hematopoiesis

Answer 3

blood+making

Question 4

what are the two types of common progenitor cells?

Answer 4

• Common myeloid progenitor

- common lymphoid progenitor

Question 5

What types of cells stem from the common myeloid progenitor cells?

Answer 5

• RBCs, platelets, granulocytes, monocytes, macrophages, dendritic cells
• makes the most different types of cells

Question 6

What types of cells stem from the common lymphoid progenitor cells?

Answer 6

gives rise to all B cells, T cells, NK cells, dendritic cells

Question 7

What are the three primary ways blood cells are distinguished?

Answer 7

• appearance and behavior
• flow cytometry
• fluorescence microscopy

Question 8

Neutrophils

Answer 8

• most common
• nuclei stain deep purple
• granules/cytoplasm stain lilac
• highly motile and extremely phagocytic

Question 9

During infection, numbers of ______ increase significantly and are recruited to the site of infection by damage cues (chemokines).

Answer 9

neutrophils

Question 10

Eosinophils

Answer 10

• minority (1-4%)
• nuclei stain deep purple
• granule contents are basic, making them attractive to eosin staining them more pink
• motile and phagocytic
• significant role in response to large, multicellular pathogens like parasitic worms

Question 11

Basophils

Answer 11

• very small minority
• nonphagocytic and contain large cytoplasmic granules filled with acidic contents
• stain very well with basic hematoxylin (deep purple)
• in response to infection, they release their granules, which are filled with histamine

Question 12

Mast cells

Answer 12

• undifferentiated cells
• released from the bone marrow as undifferentiated cells
• only mature after leaving the blood and taking up residence in tissues
• full of histamine
• responsible for allergies; inflammation
• phagocytose

Question 13

Where are mast cells located?

Answer 13

in skin, CT, and mucosal epithelia in respiratory, genitourinary, and digestive tracts

Question 14

Why is leukocytosis a sign of infection?

Answer 14

It is an increase in circulating neutrophils, which will only increase if there is infection.

Question 15

What is the primary cell type found in pus?

Answer 15

neutrophils

Question 16

What are NETs?

Answer 16

self sacrifice and project strands of their own DNA to ensnare pathogens

Question 17

What is NETosis?

Answer 17

form of cell death (apoptosis of neutrophils)

Question 18

What effects does histamine release have on the body?

Answer 18

histamine induces inflammation

Question 19

What granulocyte is primarily responsible for allergies?

Answer 19

mast cells

Question 20

What is the purpose of antigen-presenting cells?

Answer 20

a group of cells that function as cellular bridges between innate and adaptive immune systems

Question 21

During antigen presentation, if a T cell is presented its _____ _____, it will activate and begin adaptive immune responses.

Answer 21

cognate antigen

Question 22

Monocytes

Answer 22

o Make up 4-8% of leukocytes (WBC)
o Circulate in blood, but can migrate into tissues in response to infection signals
o In tissues, can further differentiate into macrophages or dendritic cells
o Large nuclei compared to other, agranulocyte

Question 23

Macrophages

Answer 23

o Pathogens marked with soluble antibody are said to be opsonized (make tasty)
o Can very efficiently engulf opsonized pathogens
o This means that once adaptive immunity is fully activated and B cells are making antibody against a pathogen, macrophages are crazy effective and finding and destroying
o (a monocyte that has navigated to tissue)

Question 24

Dendritic Cells

Answer 24

o Critical initiators of immune responses as a key bridge between innate and adaptive immunity
o Capture antigen just like other APCs, but their long dendritic extensions make their surface area large
 Can interact with many T cells at once, making them super activators of the adaptive immune response
 AKA: THE most important APCs
 are the most potent APC for activating naïve T cells
• Take in antigen by phagocytosis, endocytosis, and pinocytosis

Question 25

What cell type is responsible for forming platelets that are a necessary aspect of blood clot formation?

Answer 25

megakaryocytes

Question 26

What cells are part of the lymphoid lineage?

Answer 26

B lymphocytes T lymphocytes NK cells

Question 27

Where do B cells develop?

Answer 27

bone marrow

Question 28

What do activated B cells do?

Answer 28

* Act as APC (phagocytic and can present to T cells) * Express costimulatory receptors to activate T cells * Develop into plasma cell

Question 29

Where do T cells develop?

Answer 29

thymus

Question 30

Is an NK cell an adaptive lymphocyte or an innate lymphocyte?

Answer 30

innate lymphocyte

Question 31

How does an NK cell decide which cells too kill?

Answer 31

attacks abnormal cells that lack MHC expression

Question 32

Where does the majority of hematopoiesis occur in a developing fetus during the first trimester?

Answer 32

yolk sac

Question 33

Where does the majority of hematopoiesis occur in a developing fetus during the second trimester?

Answer 33

liver

Question 34

Where does the majority of hematopoiesis occur in a developing fetus during the third trimester?

Answer 34

bone marrow

Question 35

As humans age, we lose some of the areas where hematopoiesis occurs. Compare the areas that serve as hematopoiesis zones in a 10 year old, 25 year old, and a 50 year old.

Answer 35

10: vertebral and pelvis, tibial, sternum, ribs 25: vertebral and pelvis, sternum, ribs 50: vertebral and pelvis, sternum, ribs

Question 36

What type of cells are present in the bone microenvironment?

Answer 36

HSCs reside in specialized microenvironments, or stem cell niches. Lined with supportive cells that regulate survival, proliferation, differentiation, and trafficking. • Osteoblasts  generate bone and control HSC differentiation • Endothelial cells  line blood vessels and regulate HSC differentiation • Sympathetic neurons  control release of cells from bone marrow • HSCs and progenitor development are controlled with a stream of cytokines and growth factors

Question 37

Why does bone get less and less able to perform hematopoiesis as we age?

Answer 37

as we age, bone marrow is slowly converted to adipose tissue; approaches 50% and decreases hematopoiesis

Question 38

Where do T cells develop?

Answer 38

T cell progenitors develop initially in the bone marrow, but then migrate to the thymus where they achieve full maturity.

Question 39

What is negative selection of T cells?

Answer 39

if bind too tightly or recognize self-peptides (Kills every cell that recognizes self-molecules and will not attack body)

Question 40

What is positive selection of T cells?

Answer 40

if bind “just right” ensuring they will recognize MHC. (Kills every cell that doesn’t match MHC)

Question 41

What are the three primary secondary lymphoid organs?

Answer 41

- lymph nodes - spleen - X-associated lymphoid tissue

Question 42

What do all secondary lymphoid organs have, despite their different overall anatomies?

Answer 42

- anatomically distinct regions of T cell and B cell activity - lymphoid follicles

Question 43

How are SLOs connected?

Answer 43

via the blood and lymphatic circulatory systems

Question 44

How much lymph fluid is returned to the circulatory system each day?

Answer 44

~2.9 L a day

Question 45

What can occur when lymph is not efficiently returned to the circulatory system?

Answer 45

lymphedema results and effects on immune reaction are evident

Question 46

Where do T cells enter a lymph node?

Answer 46

o Naïve T lymphocytes enter via the high endothelial venules of the blood stream to enter the cortex.

Question 47

Where do B cells enter a lymph node?

Answer 47

through high endothelial venules (like T cells)

Question 48

Where are T cells found when they are searching for antigen?

Answer 48

o They browse APCs in the paracortex (takes 16-24 hours to browse the APCs in a single lymph node)  APCs on a network of fibers created by fibroblastic reticular cells known as the fibroblastic reticular cell conduit system. • This system serves as a highway where T cells are guided by adhesion molecules and chemokines

Question 49

Where do nonactivated lymphocytes exit?

Answer 49

o If they do not find their MHC peptide match, they leave via the efferent lymphatics (T cells)

Question 50

Effector memory cells

Answer 50

continue to circulate among all tissues

Question 51

Central memory cells

Answer 51

take up residence in secondary lymphoid organs

Question 52

Resident memory cells

Answer 52

settle in nonlymphoid tissue

Question 53

What occurs in germinal centers?

Answer 53

facilitate the generation of B cells with increased receptor affinity through somatic hypermutation

Question 54

What dictates which B cells live to become effector plasma cells?

Answer 54

- activated b cells fight for antigen in these centers - once done, the surviving cells make even better antibodies and move to the medulla to secrete antibodies into the bloodstream - germinal centers take 4-7 days to establish and last about 3 weeks

Question 55

Where do antigens/APCs enter the spleen?

Answer 55

via splenic artery

Question 56

Where are T cells found when they are searching for antigens in the spleen?

Answer 56

browse APCs in PALS

Question 57

Where are B cells found when they are searching for antigens in the spleen?

Answer 57

encounter antigen in follicles, find TH match, and then create germinal centers in follicles

Question 58

Where do nonactivated lymphocytes exit the spleen?

Answer 58

splenic artery

Question 59

What does NET stand for?

Answer 59

Neutrophil Extracellular Trap

Question 60

How do CD4+ cells recognize antigens?

Answer 60

- professional APCs use MHC II to present | - browse surfaces of APCs with TCRs looking for matching antigen (if found become subset of T cells)

Question 61

How do CD8+ cells recognize antigens?

Answer 61

-somatic cells use MHC I to present -browse surfaces of APCs with TCRs looking for match -if found, activate and become effector cytotoxic T cells (great for virus-infected cells, tumor cells)

Question 62

Once activated, Helper T cells produce cytokines to activate:

Answer 62

B cells, Cytotoxic T cells, macrophages, etc. | -changes behavior and response of immune system

Question 63

Antigen Presenting Cells include:

Answer 63

- monocytes - macrophages - dendritic cells

Question 64

Cluster of Differentiation

Answer 64

defined subset of cellular surface receptors that ID cell type and stage of differentiation, and which are recognized by antibodies

Question 65

What is the difference between the activation of NK cells and CD8+ cells?

Answer 65

- CD8+ cells browse APCs for antigen to match their antigen receptors - NK cells attack cells that do not display MHC I receptors. Do NOT have antigen-specific receptors

Question 66

Function of Osteoblasts

Answer 66

generate bone and control HSC differentiation

Question 67

Function of Endothelial cells

Answer 67

line blood vessels and regulate HSC differentiation

Question 68

Function of sympathetic neurons

Answer 68

control release of cells from bone marrow

Question 69

Where does entry of naive double negative thymocytes occur?

Answer 69

CMJ

Question 70

Where do double negative thymocytes proliferate and generate TCRs, CD4, and CD8?

Answer 70

subscapular cortex

Question 71

Where are double positive thymocytes tested for their ability to bind MHC complexes via cTECs? (Positive selection)

Answer 71

cortex

Question 72

Double positive thymocytes are tested for their ability to bind MHC cocmplexes via

Answer 72

cTECs

Question 73

Single positive thymoctyes are tested for their ability to bind proteins found in other organ types via mTECs in the

Answer 73

medulla

Question 74

Single positive thymocytes are tested for their ability to bind proteins found in other organ types via

Answer 74

mTECs

Question 75

Lymphoid follicles

Answer 75

organized microenvironments that are responsible for the development and selection of B cells that produce high-affinity antibodies

Question 76

In a lymph node, where are B cells located?

Answer 76

cortex

Question 77

In a lymph node, where are T cells located?

Answer 77

paracortex

Question 78

In a lymph node, where do lymphocytes exit and plasma cells make antibodies to enter circulation?

Answer 78

medulla