Microbiology A4 Lecture 4

Front 1

What are the two types of immunity? Describe them.

Back 1

Innate - non-specific, potentially ever-present, rapidly available, no memory. Example: Skin

Specific - discrimination between self and non-self. Adaptive. Memory.

Front 2

What are the definitions of:

1) Antigen
2) Antibody
3) Immunogen

Back 2

1) Antigen - that which attaches to an antibody

2) Antibody - immunoglobulin (protein) that combines with an antigen

3) Immunogen - substance that stimulates an immune response.

Front 3

What are the two different progenitors of cells that arise from a pluripotent stem cell?

Back 3

1) Myeloid progenitor
2) Lymphoid progenitor

Front 4

What cells come from myeloid progenitor cells?

Back 4

Immature dendritic cell, erythrocytes, platelets, monocytes, eosinophils, neutrophils, basophils

Front 5

What cells from from lymphoid progenitor cells?

Back 5

B lymphocytes, T lymphocytes, Natural killer cells

Front 6

What do monocytes differentiate into in tissues?

Back 6

Macrophages and dendritic cells.

Front 7

What are the most important cell type in specific immune response? What kind of immune response do they participate in (innate or specific?)

Back 7

Lymphocytes - participate in specific immunity.

Front 8

What is the responsibility of lymphocytes? What structures are lymphocytes present in?

Back 8

Conduct immune surveillance. Responsible for recognizing a specific antigen and for making the response to the specific antigen once it's recognized.

Present in blood, lymph, lymphoid tissue.

Front 9

Lymphocytes compose what % of peripheral blood leukocytes?

Back 9

30%

Front 10

How are B cells and T cells named?

Back 10

According to where they're produced. B cells are made in bone marrow, T cells mature in the thymus.

Front 11

What are the two types of lymphocytes?

Back 11

B cell and T cell.

Front 12

What % of blood lymphocytes are B cells? T cells?

Back 12

B cells - 4-12% of blood lymphocytes
T cells - ~70% of blood lymphocytes

Front 13

What % of lymphocytes are B cells and T cells combined? What about the rest of the %?

Back 13

87%. Other 13% are non-T, non-B cells that used to be a B or T cell but have lost that marker.

Front 14

What does the B cell do once it's activated? T cell?

Back 14

Activated B cell becomes plasma cell, makes antibodies for HUMORAL immunity.

Activated T cells either help (helper T cells), regulate, kill.

Front 15

Describe humoral vs. cell-mediated immunity.

Back 15

Humoral is antibody mediated immunity (B cells)

Cell-mediated is T cell mediated immunity

Front 16

How do we distinguish between individual cells?

Back 16

Cell surface markers, aka CD = clusters of differentiation. Membrane proteins that characterize different cell types and subsets.

Front 17

What are CDs?

Back 17

Cluster of differentiation, membrane proteins that characterize different cell types and subsets.

Front 18

How many CD markers are there and how are they identified?

Back 18

~400, identified by monoclonal antibodies.

Front 19

What are monoclonal antibodies? How are they produced? Do we make them?

Back 19

Antibodies that are derived from a single cell line. Produced by stimulating plasma cells with a specific antigen, use the specific antibody that results. We ONLY make polyclonal antibodies. One exception is in a certain form of cancer.

Front 20

What CD do all T cells have?

Back 20

CD3.

Front 21

What is a TCR, and which CD is usually found with it?

Back 21

T cell receptor, which recognizes a specific antigen. Usually found with CD3.

Front 22

What are the major CD markers for T cells?

Back 22

CD3, CD4, CD8.

Front 23

What CD does the HIV virus target, and what does this mean for certain cells?

Back 23

CD4, which are found on all T cells. HIV virus binds to CD4 and destroys T cells.

Front 24

What are the B lymphocyte markers?

Back 24

BCR, CD19, CD21 (aka CR2)

Front 25

What is an interesting feature of the BCR? Describe it.

Back 25

It has an antibody stuck in the membrane, that is almost identical to the secreted antibody. Internal cytoplasmic bed is different, but antigen binding part is the same.

Front 26

What are the limitations for TCR recognizing an antigen?

Back 26

Only recognizes antigen if it's presented to it by an antigen-presenting cell. Cannot recognize free or soluble antigen.

Front 27

What are some examples of antigen presenting cells (for TCR?)

Back 27

Monocytes, macrophages, even some B lymphocytes.

Front 28

What structure do antigen presenting cells present antigens in?

Back 28

MHC. Major histocompatibility complex.

Front 29

Which CDs are associated with BCRs and TCRs? What is the reason for this?

Back 29

BCR - CD79
TCR - CD3

The cytoplasmic tails of the receptors are short, only a couple AA long. Use the CD tails (much longer) to transmit the signal forward.

Front 30

Describe the process of clonal expansion, starting from naive cells.

Back 30

Naive cells -> antigen recognition -> clonal expansion -> differentiation -> effector cells + memory cells

Front 31

What are the effector cells of B lymphocytes? Helper T cells? What do these effector cells produce?

Back 31

B lymphocyte effector cells = plasma cells. Produce antibodies.

Helper T cells = lymphoblast. Produce cytokines.

Front 32

What are lymphoblasts?

Back 32

Immature cells that differentiate to form mature lymphocytes.

Front 33

How does a picture of Th lymphoblasts compare to a lymphocyte? What about a plasma cell?

Back 33

Th lymphoblast - Much larger, lots more cytoplasm, not quite as dense as a lymphocyte.

Plasma cell - huge amount of cytoplasm, LOTS of RER because it's making antibodies (protein)

Front 34

Compare humoral immunity vs. cell-mediated immunity.
What does it protect against?

Back 34

Humoral: extracellular and toxins.

1. EXTRACELLULAR MICROORGANISMS ONLY (most bacteria, viruses during viremic [viruses in the blood] stage)

2. Can neutralize toxins, like tetanus toxins.

Cell mediated immunity

1. Intracellular organisms (viruses that have infected cell, few bacteria, like mycobacteria which causes TB)
2. Fungi
3. Parasites

Front 35

What does humoral immunity require in order to function?

Back 35

Cell-mediated immunity!

Front 36

If HIV destroys a patient's T cells, what other infections are they susceptible to?

Back 36

Viral infection, TB, fungal, parasitic

Front 37

What is the progenitor of natural killer cells? What is another name for NK cells? What is the function of natural killer cells? What CDs do NK cells possess, what do they lack?

Back 37

Lymphoid cells. Large granular lymphocytes. Kills infected and malignant cells.CDs: 56, 16, lack CD3 and antigen receptors

Front 38

If you see CD56 and 16 and no CD3, what cell is it?

Back 38

Natural killer.

Front 39

If you see CD79, CD19, and CD21, what cell is it?

Back 39

B cell.

Front 40

If you see CD3, CD4, or CD8, what cell is it?

Back 40

T cell.

Front 41

What CDs are associated with natural killer cells?

Back 41

CD56, CD16.

Front 42

What kind of immunity do mononuclear phagocytes play a role in? What types of cells are mononuclear phagocytes?

Back 42

Innate and specific. Monocytes and anything derived from them (macrophages, dendritic cells).

Front 43

What are the mononuclear phagocytes and what is their job?

Back 43

Monocyte, macrophage, microglia, kupffer, alveolar macrophages, osteoclasts.

Phagocytosis, antigen processing and presentation.

Front 44

List mononuclear phagocytes and where they're found.

Back 44

Monocyte ->

1. macrophage in tissues
2. microglia (CNS)
3. Kupffer Cells (liver)
4. alveolar macrophages (lung)
5. osteoclasts (bone)

Front 45

How do you identify a monocyte in histology?

Back 45

Kidney shaped nucleus, lots of cytoplasm.

Front 46

What is the function of dendritic cells? What are they characterized by? What progenitors give rise to dendritic cells?

Back 46

Function: antigen-presenting cells. Present peptides and proteins to B and T lymphocytes.

Characterized by long membranous extensions.

Both myeloid and lymphoid.

Front 47

What are four different types of dendritic cells? Where are they found and what are their progenitors?

Back 47

MYELOID PROGENITOR
1. Langerhans cells (immature DC) - found in skin.

2. Interstitial DC (immature) - found in interstitial spaces.

3. Monocyte-derived DC - come directly from monocytes

LYMPHOID PROGENITOR
4. Interstitial dendritic cells

Front 48

What are the function of immature dendritic cells? When do they mature?

Back 48

Function - antigen uptake, presentation to T cells.

Mature following activation by cytokines or microbial products.

Front 49

What are Langerhans cells? Where are they found? What is a defining characteristic? Where do they migrate to?

Back 49

Immature dendritic cells. Found in skin. Defining characteristic = Birbeck granule "tennis racquets". Migrate from skin to lymph node.

Front 50

What are interstitial dendritic cells? Where are they found? What do they interdigitate with?

Back 50

Immature dendritic cells. Found in most organs, but not the brain. Interdigitate with T cell areas of lymphoid tissue, thymic medulla.

Front 51

What are follicular dendritic cells? Where are they found? Why are they unique?

Back 51

Non-lymphoid cells, found in lymph nodes (mostly where B cells are found. Unique because they bind antigen-antibody complexes for months to years, present ONLY to B cell, do not present to T cell. Play a huge role in their maturation and memory. Also the site of virus reservoir for HIV.

Front 52

What are polymorphonuclear leukocytes also known as? What is their progenitor? What three important cells arise from it?

Back 52

Also known as granulocytes. Myeloid stem cell progenitor. Basophil, eosinophil, neutrophil.

Front 53

What kind of cells are basophils, eosinophils, and neutrophils? What progenitor do they arise from? What color do they stain? What is the function of each?

Back 53

Granulocytes. Arise from myeloid stem cell progenitors.

Basophils - stain blue, involved in allergies.

Eosinophils - stain red, very important in defense against large parasites like worms.

Neutrophils - stains neutral, by far the most abundant. Most important cell in innate immunity, phagocytic.

Front 54

What is the most important cell in innate immunity and what is its main function?

Back 54

Neutrophil - phagocytic.

Front 55

Where are mast cells found? What color do they stain? What granulocyte is it closely related to?

Back 55

Found in tissues, stain blue. Closely related to basophils.

Front 56

Where are T cells processed? B cells?

Back 56

T cells - thymus. B cells - bone marrow.

Front 57

When do you make a vast majority of your T cells? When is the thymus at its greatest size? When does it involute by?

Back 57

By the time you're two years old. Thymus is at its greatest size then. Involutes by puberty.

Front 58

Thymus:

1) How many lobes does it have?
2) What does it originate from?
3) What are the two sections of the thymus?
4) What is the main function of the thymus?
5) When is it most active?
6) Why is the thymus unique histologically?

Back 58

1) 2+ lobes
2) Originates from 3rd pharyngeal pouch.
3) Cortex, medulla
4) Process T cells - a small amount of thymocytes survive and leave thymus as T cells
5) Most active during first two years of life
6) Because medulla is continuous throughout thymus

Front 59

What are T cell precursors known as?

Back 59

Thymocytes.

Front 60

Are there lymph nodules in the thymus?

Back 60

No.

Front 61

Where are immature thymocytes located in the thymus? Where are mature T-cells located?

Back 61

Immature in cortex, mature in medulla.

Front 62

As the thymus atrophies, what kind of tissue takes it over?

Back 62

Adipose.

Front 63

What kind of cells make up the thymus? What layer are these cells derived from? What is the function of these cells?

Back 63

Epithelial reticular cells (ERC) derived from pouch endoderm.

Function: self antigen presentation to T cells, production of thymic hormones necessary for T cell maturation.

Front 64

Where is Hassall's corpuscle found? What type of cells is it comprised of? What layer are these cells derived from?

Back 64

Found in the medullary part of the thymus. Comprised of Type VI ERC (epithelial reticular cells), derived from ECTODERM.

Front 65

What is the function and structure of the cortical ERC in the thymus?

Back 65

One cell layer that separates the cortex from the medulla, and forms the blood-thymus barrier.

Front 66

What are the cell hormones necessary for T cell maturation? What produces them?

Back 66

1) Thymosin
2) Thymopoeitin
3) Thymulin
4) Thymic humoral factor

Produced by ERC.

Front 67

What structure are epithelial reticular cells (ERC) unique to?

Back 67

Thymus.

Front 68

What is the function of the lymph nodes? Name the cervical lymph nodes and their locations.

Back 68

Filter antigens in lymph which drains to tissues.

1) Preauricular - in front of ear
2) Submandibular - below mandible
3) Submental - under the chin
4) Anterior cervical - In front of the cervix
5) Supraclavicular - On top of clavicle

Front 69

Where are B cells housed in the lymph node?

Back 69

In the primary lymphoid follicle, or nodules.

Front 70

What are germinal cells in lymph nodes? What is a nodule called if it has a germinal center in it?

Back 70

Germinal center in lymph node = where B cells are differentiating. Called secondary lymphoid follicle if germinal center is present in nodule.

Front 71

Map the passage of lymph through a lymph node.

Back 71

Lymph comes in through afferent vessel, -> subcapsular sinus (lined with enodthelial cells) -> cortical sinus (B cells) -> paracortical area (T cells) -> Medullary sinus -> exits through efferent vessel.

Front 72

Where are T cells housed in a lymph node?

Back 72

The paracortical area.

Front 73

What is the function of the medullary cords in the lymph node?

Back 73

Houses macrophages and plasma cells.

Front 74

What feature on afferent lymph vessels makes sure that lymph only flows in one direction?

Back 74

Valves.

Front 75

What is happening in follicular hyperplasia? When is this typically seen?

Back 75

When lymph node is being bombarded all over - cortex and medulla. Filled with nodules. Seen in early stages of HIV infection.

Front 76

What are the two main ducts for lymph and what do they drain into?

Back 76

Thoracic duct - drains into left subclavian vein, goes back into blood.

Right lymphatic duct - drains into right subclavian vein, goes back into blood.

Front 77

What is the role of the spleen? How is it differ from lymph nodes?

Back 77

Spleen filters antigens in blood. Lymph nodes filter antigens in lymph.

Front 78

What is contained in the red pulp of the spleen? What is housed in these structures?

Back 78

1. Splenic sinuses
2. Splenic cords of Billroth
- reticular fibers, RBC, macrophages

Front 79

What is contained in the white pulp of the spleen? What is housed in each of these structures?

Back 79

1) PALS (periarteriolar lymphatic sheath) - houses t cells

2) Lymphoid nodules with B cells

Front 80

What are the three types of mucosa associated lymphoid tissues?

Back 80

1) GALT - gut associated lymphoid tissues

2) BALT - bronchus associated lymphoid tissues

3) Tonsils

Front 81

What are some examples of GALTs? (Gut associated lymphoid tissues)?

Back 81

Peyer's patches, appendix, M cells

Front 82

What is the full name for M cells? Where are they found? What is their function?

Back 82

Microfold cells. Found in Peyer's patches in appendix. Phagocytose and transport antigens from gut lumen into the inside of the gut wall, where lymphocytes are. It's very easy for antigens to get across because the distance from the antigens and the effector cells are very small

Front 83

Name all the types of tonsils, how many there are, and kind of tissues they're made out of histologically. Any features?

Back 83

1) Palatine (2) - Stratified squamous nonkeratinized epithelium, marked by crypts

2) Pharyngeal (1) - pseudostratified ciliated columnar epithelium interspersed with stratified squamous epithelium; pleats

3) Lingual (several) - stratified squamous nonkeratinized epithelium

Front 84

Where are Peyer's patches found? What kind of lymphocytes are in there predominantly?

Back 84

In the appendix. B lymphocytes found predominantly in there.

Front 85

Which tonsils get really enlarged when the person has an infection? What is it called when the throat is sore and swollen? What is the bacterial cause of this? How do you know when a virus is causing it?

Back 85

Palatine tonsils. Pharyngitis. Strep. If there's a virus cause, there's no pus.

Front 86

What is a histological feature of palatine tonsils? What cells make up most of these tonsils?

Back 86

Crypts. 35% = M cells.

Front 87

What is a tonsil stone, or tonsil lithe, a result of?

Back 87

Bacteria, cell debris, pus getting stuck in the villi of palatine tonsils and getting calcified.

Front 88

Can you normally see lingual tonsils?

Back 88

No, not unless they're inflamed.

Front 89

What cells specifically make up the medulla in the thymus?

Back 89

Hassell's corpuscle, type VI ERC, ectodermal origin.

Front 90

Which body parts drain into the right lymphatic duct?

Back 90

Upper right head, right chest, arm, torso.

Front 91

What are the mononuclear phagocytes?

Back 91

Monocytes, macrophages.

Front 92

What responds to bacteria, humoral or cell-mediated immunity? Viruses?

Back 92

Bacteria - humoral. Viruses - cell-mediated.

Front 93

What are the polymorphonuclear leukocytes?

Back 93

Basophils, eosinophils, neutrophils.