Lecture 7: Introduction To Immune System

Question 1

The humoral response is mediated by Abs produced by B lymphocytes and responds to ____________ pathogens, whereas the cell-mediated response is mediated by thymus-dependent lymphocytes called T lymphocytes and responds to _____________ pathogens

Answer 1

Extracellular; intracellular

Question 2

______ lymphocytes develop from precursors during lifetime

Answer 2

B

Question 3

All _____ lymphocytes are generated in the ___________ early in life

Answer 3

T; thymus

Question 4

What do BCRs recognize?

Answer 4

Various Ags: Proteins, carbs, lipids and nucleic acids

Question 5

B cells (plasma cells) produce Abs that are secreted into the ____________ and ___________ fluids

Answer 5

circulation;mucosal

Question 6

What do TCRs recognize?

Answer 6

Peptide Ags only

Question 7

What is the role of T helper cells?

Answer 7

Produce cytokine IFN-gamma to stimulate macrophages to destroy microbes in phagosome

Question 8

What is the role of CTLs

Answer 8

Kill infected cells

Question 9

What cell types are considered professional APCs?

Answer 9

DCs, macrophages and B cells

Question 10

What is the role of professional APCs?

Answer 10

When activated, professional APCs activate both T helper and CTLs

• They are not killed and continue Ag presentation for other cells

Question 11

What cell types are considered non-professional APCs?

Answer 11

Any nucleated cell in the body

Question 12

When infected with intracellular pathogens, non-professional APCs activates only _____________ lymphocytes which kill the infected non-professional cell

Answer 12

Cytotoxic T

Question 13

When Ags are captured by APCs, microbes enter through an epithelium and are captured by ________ resident in the epithelium. These cells then transport Ags to the ____________ where protein Ags are displayed for recognition by T lymphocytes.

Answer 13

DCs; lymph nodes

Question 14

Blood borne Ags are presented by APCs in the _________

Answer 14

Spleen

Question 15

What professional APCs carry microbial Ags out of the lymph nodes?

Answer 15

DCs

Question 16

APCs resent Ags to T lymphocytes congregated in the special areas called __________ zones

Answer 16

T cell

Question 17

What delivers Ags to B cells and where?

Answer 17

Lymph! (Not DCs); delivers Ags to B cells congregated in the special areas called B cell zones

Question 18

Each splenic arteriole is surrounded by the ______________ _______________ sheath

Answer 18

Periarterial lymphoid sheath (PALS)

Question 19

PALS contains T cell and B cell zones and is attached to follicle containing a _____________ ___________

Answer 19

Germinal zone

Question 20

The PALS and lymphoid follicles together constitute what?

Answer 20

The white pulp

Question 21

White pulp is surrounded by the __________ ___________ which is rich in vascular sinusoids

Answer 21

Red pulp

Question 22

_________________ APCs express class I MHC only

Answer 22

Non-professional

Question 23

_______________ APCs express both class I and class II MHC

Answer 23

Professional

Question 24

What cell types express both class I and class II MHC, but not the TCRs or BCRs?

Answer 24

Macrophages and DCs

Question 25

What cell types express the TCR and class I MHC, but not class II MHC or BCRs?

Answer 25

T cells

Question 26

What cell types express BCRs and both class I and class II MHC molecules, but not TCRs?

Answer 26

B cells

Question 27

What cell types express class I MHC only?

Answer 27

Granulocytes

Question 28

What cell types do not express MHC, BRCs or TCRs?

Answer 28

Erythrocytes

Question 29

Microbial Ags are taken up by professional APCs via ____________ by macrophages or _____________ by DCs and B cells

Answer 29

Phagocytosis; endocytosis

Question 30

Are Ag-free MHC molecules displayed on APCs?

Answer 30

No! No Ag-free MHC molecules are displayed on APCs

Question 31

An Ab is a tetramer of 2 pairs of identical ________ and _______ chains

Answer 31

Heavy and light

Question 32

Both heavy and light chains of an Ab have __________ and ___________ domains

Answer 32

Variable and constant

Question 33

The variable region of an Ab confers ________________

Answer 33

Ag recognition

Question 34

The heavy chain of an Ab contains a _________ domain that confers flexibility to allow optimal Ag binding

Answer 34

Hinge

Question 35

The _________ region, termed Fc, determines the effector property of Abs

Answer 35

Constant

Question 36

Distinct biological activities attributed to each heavy chain molecule of an Ab via their unique _________ part

Answer 36

Fc

Question 37

What are the various types of heavy chains of Abs?

Answer 37

Gamma, alpha, mu, epsilon, delta

Question 38

What are the different types of light chains of Abs?

Answer 38

Kappa and lambda

Question 39

The Ag-binding fragment obtained by proteolysis with ___________ contains 2 Ag-binding sites termed Fab fragments and Fc fragment

Answer 39

Papain

Question 40

The Ag-binding fragment obtained by proteolysis with __________ contains 2 Ag-binding sites and is termed F(ab')2

Answer 40

Pepsin

Question 41

Abs are classified according to their _________ chains

Answer 41

Heavy

Question 42

How many subclasses does IgG have?

Answer 42

4: IgG1, IgG2, IgG3, IgG4

Question 43

How many subclasses does IgA have?

Answer 43

2: IgA1 and IgA2

Question 44

What Ab is a dimer in the secreted form?

Answer 44

IgA

Question 45

What Ab is a pentamer in the secreted form?

Answer 45

IgM

Question 46

Where does IgA mainly act?

Answer 46

Mucosal immunity and neonatal passive immunity

Question 47

What Ab is the naive B cell Ag receptor?

Answer 47

IgD

Question 48

What Ab causes mast cell activation?

Answer 48

IgE

Question 49

What Ab is responsible for opsonization, complement activation, Ab-dependent cell-mediated cytotoxicity, neonatal immunity and feedback inhibition of B cells?

Answer 49

IgG

Question 50

What Ab is a naive B cell Ag receptor and activates the complement

Answer 50

IgM

Question 51

Which Ab is highest in the serum?

Answer 51

IgG

Question 52

What are the 6 effector mechanisms of antibodies?

Answer 52

``` Neutralization Agglutination Activation of complement Opsonization Ab-dependent cell-mediated cytotoxicity (ADCC) Degranulation ```

Question 53

Explain the antibody effector mechanism of agglutination

Answer 53

Cross-linking occurs because Abs possess 2 identical Ag-binding sites -> microbes can be agglutinate into mesh-like structures called immune complexes

Question 54

Explain the antibody effector mechanism of opsonization

Answer 54

Abs can bind to Fc receptors on macrophages and neutrophils that enhances phagocytosis

Question 55

Explain the Ab effector mechanism of Ab-dependent cell-mediated cytotoxicity (ADCC)

Answer 55

Fc receptors on NK cells -> Ab-tagged killing of tumor cells and virus-infected host cells

Question 56

Explain the Ab effector mechanism of degranulation

Answer 56

Degranulation of mast cells, basophils and eosinophils - IgE binding to Fc receptors on the cells

Question 57

``` A 23-year-old woman had been having diarrhea for 3 days. She reports to her primary care physician and he does an endoscopy. She notes that the outermost layer of her luminal surface is missing. What is this layer? A) Goblet cells B) Lamina propria C) Microvilli D) Simple columnar epithelium E) Villi ```

Answer 57

C) Microvilli

Question 58

All of these features are false about the spleen except: A) Macrophages sheathe the radial arteries in order o remove damaged RBCs and debris B) Penicillar arteries feed the marginal zone sinuses of the white pulp C) Red pulp is made of RBCs, includes a marginal layer and a germinal center D) Blood flow originates from the splenic Avery, flowing eventually into penicillar arteries that either feed into splenic sinusoids or red pulp E) The spleen is made up of an outer cortex and 2 main compartments, Red and white pulp

Answer 58

D) Blood flow, originates from the splenic artery, flowing eventually not penicillar arteries that either feed into splenic sinusoids or red pulp

Question 59

``` While observing keratinocytes in a blown up picture of your patient you notice oval nuclei, lots of desmosomes and spine-like processes. You know these keratinocytes come from: A) Stratum basale B) Stratum corneum C) Stratum granulosum D) Stratum spinosum E) Stratum lucidum ```

Answer 59

D) Stratum spinosum

Question 60

While hurrying over to Smith Hall to reserve a room for your intense test preparation you scrape your knee after taking a nasty fall on the slippery sidewalk. Normally you would yell in pain, however you know the process of wound healing and begin to formulate in your head that: A) The first step involves inflammation and recruitment of a mass number of neutrophils via chemokines B) Keratinocytes from the surrounding stratum granulosum and stratum spinosum layer create a bridge in the development of new skin under the scab C) Migration occurs by detachment of hemidesmosomes while the underlying dermis contracts to bring edges of the wound together D) PDGF is released from he cleavage from fibrinogen to form fibrin in order to recruit more platelets

Answer 60

C) Migration occurs by detachment of hemidesmosomes while the underlying dermis contracts to bring edges of the wound together

Question 61

In the body a barrier regulates exchange of substances between the circulatory system and thymus, providing a sequestered environment for immature T cells to develop. The barrier also prevents the immature T cells from contacting foreign Ags. Where is this barrier located?

Answer 61

In the peripheral cortex of the thymus

Question 62

``` Which of the following splenic arteries are surrounded by a very thin perilymphatic sheath (PALS) that disappears as the arteries in a brush-like pattern that ramify gradually into capillaries upon entering the red pulp? A) Central arteries B) Left gastroepiploic C) Penicillar arteries D) Radial arteries E) Short gastric arteries ```

Answer 62

C) Penicillar arteries