L11

Question 1

Defense against pathogens is the

Answer 1

principal physiologic function of the immune system

Involves both the innate and adaptive immune response

Question 2

Different pathogens trigger

Answer 2

distinct immune responses and effector mechanisms

Question 3

Pathogens have mechanisms to

Answer 3

evade the immune response

Question 4

INNATE IMMUNITY

Answer 4

MACROPHAGES
NEUTROPHILS
COMPLEMENT SYSTEM

Question 5

ADAPTIVE IMMUNITY

Answer 5

B cells and Antibody (IgG)
T cells (indirect help by helper CD4+ T cells)

Question 6

Neutrophils and Macrophages will

Answer 6

remove particulate antigen by phagocytosis

Question 7

HIGH AFFINITY RECEPTORS: Mannose receptor

Answer 7

• binds mannose on microbial cell wall mediating cell-microbe binding and initiating phagocytosis

Question 8

HIGH AFFINITY RECEPTORS: Mac-1 Integrin-

Answer 8

Binds microbes opsonized with complement proteins

Question 9

HIGH AFFINITY RECEPTORS: Scavenger receptor-

Answer 9

binds microbes in a non-mannose specific manner

Question 10

Opsonin –

Answer 10

derived from a Greek word meaning “to prepare for eating”.
Antibodies
Complement Proteins
Lectin

Question 11

OPSONIZATION of a microbe occurs when it is

Answer 11

coated/bound by an opsonin to target it for phagocytosis (mediates binding to phagocyte receptors).
More efficient than mannose receptor mediated phagocytosis
Enhances inflammation and antimicrobicidal activity

Question 12

RNI=

Answer 12

REACTIVE NITROGEN INTERMEDIATES
Nitric Oxide (NO)

Question 13

Exaggerated/strong activation of macrophages and neutrophils can

Answer 13

injure normal host tissue by release of lysosomal enzymes ROS and NO
Microbicidal products do not distinguish between self tissue and microbes or normal tissue and infected tissue

Question 14

CD8 +T cell role in

Answer 14

immunity against intracellular microbes

Question 15

CD8+T Recognize

Answer 15

antigen in a MHC I restricted manner

Question 16

CD8+T called

Answer 16

CALLED CYTOTOXIC T CELLS as they secrete perforin and granzymes which will directly lyse/kill infected cells
Very important for anti-viral immunity

Question 17

CD8+T Secrete

Answer 17

cytokines such as IFN-g and TNF-a

Question 18

CD8+ T cells also

Answer 18

kill phagocytes which have engulfed microbes

Question 19

Macrophage: Remove

Answer 19

particulate Antigen by phagocytosis

Followed by production of ROS and RNI

Question 20

Macrophage: Take up soluble antigen, process and present antigen to

Answer 20

T cells

Question 21

Macrophage secrete

Answer 21

pro-inflammatory cytokines (IL-1, IL-6, TNF-a) and chemokines (CCL2, CXCL1, etc) that induce inflammation and immune chemotaxis
Induced through the recognition of microbial byproducts by Toll-like receptors (TLRs) and Nod-like receptors (NLRs)

Question 22

Which Th cell would be needed against intracellular infections?

Answer 22

Th 1

Question 23

Neutrophil: Migrate toward the site of

Answer 23

inflammation within an hour of tissue injury in response to chemotactic factors
IL-8
IFN-g
C5a

Question 24

Neutrophil Effectively phagocytose

Answer 24

microbes

Can eliminate microbes via ROS and RNI

Question 25

Neutrophils Can also kill microbes by

Answer 25

``` oxygen independent mechanisms DEGRANULATION (release of granuoles) Defensins Myeloperoxidase Neutrophil extracellular traps (NETs) ```

Question 26

Role of COMPLEMENT in Immunity against Extracellular Microbes:

Answer 26

Serves as an opsonin and enhances phagocytosis by phagocytes Serves as a chemokine and recruits and activates leukocytes to the site of inflammation Forms the membrane attack complex (MAC) and mediates lysis of the microbe

Question 27

B cells produce

Answer 27

antibody Neutralization Opsonization Memory

Question 28

B cells express

Answer 28

MHC II and can present antigen to T cells

Question 29

Bacterial products can directly

Answer 29

activate B cells in a T cell independent manner

Question 30

CD4+ T cells can also make

Answer 30

inflammatory cytokines (IFN-g and TNF-a) These cytokines activate macrophages and promote phagocytosis, bacterial killing and inflammation Called Th1 cells when they make these inflammatory cytokines

Question 31

CD4+ T cells (helper T cells) produce

Answer 31

cytokines (IL-4, IL-5 and IL-10) These cytokines are B cell growth factors which activate B cells and promote antibody production Called Th2 cells when they make these B cell promoting cytokines

Question 32

Which Th response is more important during extracellular defense?

Answer 32

Th 2

Question 33

Mechanisms of Immune Evasion by extracellular bacteria

Answer 33

Antigenic variation Inhibition of complement activation (many bacteria) Resistance to phagocytosis (e.g. Pneumococcus) Scavenging of ROS (e.g. catalase-positive Staphylococci

Question 34

Facultative intracellular pathogen can

Answer 34

survive inside host cells to evade the immune system

Question 35

Obligate intracellular pathogen MUST

Answer 35

INFECT HOST to survive

Question 36

Injury caused by

Answer 36

host immune response | Deleterious effects on host immune system

Question 37

IMMUNITY TO INTRACELLULAR PATHOGENS

Answer 37

Both innate and adaptive immune response are involved Cell mediated immune response is dominant rather than antibody response Pathogens have mechanisms in place to survive and replicate within host cells (e.g. phagocytes) Disease and resulting pathology are a consequence of the host’s immune response to the infectious agent

Question 38

INNATE

Answer 38

``` Dendritic Cells (APC) Natural Killer (NK) cells Macrophage/Neutrophils ```

Question 39

ADAPTIVE

Answer 39

CD4+ T cells (helper T cells) | CD8+ T cells (cytotoxic T cells)

Question 40

DENDRITIC CELL

Answer 40

Professional APCs that present Ag to T cells Carry Ag from site of infection to lymph node where they will present Ag to naïve T cells Produce cytokines such as IL-12 that regulate the differentiation of CD4+ T cells (promote either Th1 generation or Th2 generation)

Question 41

NK CELL

Answer 41

Main function is to kill virus infected cells (and tumor cells) Secrete cytokines (IFN-g) required for macrophage and Th1 development Activation of NK is regulated between signals from activating and inhibitory receptors

Question 42

CD4 +T cell role in immunity against intracellular microbes

Answer 42

Recognize Antigen in a MHC II restricted manner CALLED HELPER T CELLS as their main role is to help coordinate the responses of other immune cells Differentiate into Th1 or Th2 subsets producing distinct cytokines with distinct biological activity Th1 CD4+ T cells produce IFN-g and TNF-a and promote cell mediated immunity PROVIDE HELP TO CD8+ T CELLS AND MACROPHAGES Th2 CD4+ T cells produce IL-4 and promote antibody mediated immunity PROVIDE HELP TO B CELLS