immunity to microbes part I

Question 1

infections caused by pathogenic extracelular bacteria have 2 principal mechanisms:

1. ____ causes tissue destruction at the site of infection
2. bacteria produce ____ which have diverse pathlogic effects

Answer 1

1. inflammation
2. toxins

Question 2

bacterial toxins are divided into 2 categories:

1. ____ which are components of bacterial cell walls
2. ____ whiuch are excreted by the bacteria

Answer 2

1. endotoxins
2. exotoxins

Question 3

primary infection (extracellular bacteria) activation of complement pathways:

1. alternative pathway caused by ____
2. lectin pathway caused by ____
3. classical pathway caused by ____

Answer 3

1. LPS
2. MBP
3. C-Reactive Protein

Question 4

complement causes:

1. C3a and C5a →
2. mast cells release →
3. C3b →

Answer 4

1. activate mast cells
2. histamine and proteases that enhance blood flow
3. opsonize the pathogen

Question 5

upon extracellular bacteria primary infection:

local immune cell srelease chemokines/cytokines that activates endothelial cells and attracts neutrophils, especially through cytokine ____

Answer 5

IL-8

Question 6

bacteria is opsonzied by C3b, promotes phagocytosis and killing by ____ and ____

Answer 6

neutrophils and macrophages

Question 7

bacteria can be phagocytosed by DCs and processed to Ags → presented on ____

DC engulf and internalize bacteria and are activated by ____

Answer 7

MHC II

PRRs (e.g. TLRs)

Question 8

mature DCs enter local LNs via ____ lymphatics and move to ____ cell zone

lymphocytes enter LNs via ____

DCs activate T cells (via Ag presented on MHC II) and begin ____

Answer 8

afferent T-cell

HEV

proliferation

Question 9

naive T cells become differentitated towards ____ and ____ according to the DC signals

Answer 9

Th1 and Th2

Question 10

Th cells migrate to germinal centers and interact with Ag-activated B cells resulting in ____ ____ and ____ maturatin

(early infections are characterized by ____ )

Answer 10

class switching (IgM → IgG/IgA)

affinity

IgM (low affinity with high avidity)

Question 11

IgM is a very potent ____ complement activator that generates C3b opsonin

Answer 11

classical

Question 12

some extracellular pathogens can evade immune responses:

1. variation of surface ____ is key to evading humoral immunity
2. inhibition of ____
3. resistance to ____
4. eliminate reactive oxygen species via ____

Answer 12

1. Ags
2. complement
3. phagocytosis
4. catalase

Question 13

in the resolutioin of an infection, bacterial debris is removed by local ____ and ____ , or by ____ as soluble immune complexes

Answer 13

macrophages and neutrophils

antibodies

Question 14

____ and ____ can independently (w/o MBL and CRP) actviate complement by the ____ pathway

Answer 14

alternative

Question 15

the classical pathway is activated when ____ binds to Ab attached to Ag, activating ____ and ____ which cleave ____ and ____

Answer 15

C1q

C1r and C1s

C4 and C2

Question 16

the lectin pathway is activated when ____ encounters conserved pathogenic ____ motifs, activating the ____ and cleaving ____ and ____

Answer 16

MBL

carbohydrate

MASPs

C4 and C2

Question 17

prevention of host bystander damage:

1. factor I
2. DAF, C4BP
3. CD59

Answer 17

1. inhibits assembly of C3 and C5 convertase → lack of inflammation and classical complement
2. inhibit assembly of C3 convertase → inhibit classical (C4BP) and alternative pathway
3. inhibit MAC assembly → inhibit lysis

Question 18

meutrophils and macrophages use surface TLRs, mannose receptors, and scavenger receptors to recognize extracellular bacteria. they use Fc receptors and complement receptors to recgonize intact bacteria or bacteria opsonized with Abs and/or C3b

1. TLRs activate ____ activities of phagocytes
2. mannose and scavenger recptors promote ____ of the microbes
3. Fc and complement receptors promote both ____ and ____ of the phagocytes

Answer 18

1. mimcrobicidial
2. phagocytosis
3. phagocytosis and activation

Question 19

1. TLR1 and TLR2 recognize bacterial ____
2. TLR4 detects ____
3. TLR5 recgonizes ____

Answer 19

1. lipoprotein
2. LPS
3. flagellin

these TLRs mediate NFkB activation which requires adaptor protein MyD88

Question 20

humoral effector mechanisms for extracellular microbes

1. toxin ____
2. opsonization and ____
3. ____ activation

Answer 20

1. neutralization
2. phagocytosis
3. complement

Question 21

cell-mediated immunity for extracellular microbes:

1. protein Ag of extracellular bacteria activates ____ T cells
2. Th17 recruit neutrophils and monocytes promoting ____
3. Th1 releases IFN-gamma that activates ____
4. Th2 assists with ____ responses

Answer 21

1. CD4+ helper
2. inflammation
3. macrophages (resulting in phagocytosis and killing)
4. antibody

Question 22

principal injurious consequences of host responses to extracelular bacteria are ____ and ____ ____

Answer 22

inflammation and septic shock

Question 23

septic shock:

characterized by:

Answer 23

circulatory collapse → drop in blood pressure

IV coagulation

Question 24

early phase of septic shock:

1. caused by cytokines produced by ____ causing a cytokine ____
2. TNF-alpha upregulates iNOS , IL-18 → futher activation of ____

Answer 24

1. macrophges storm
2. macrophages

Question 25

late phase of septic shock: systemic

1. cytokines stimulate production of ____ ____ ____ from liver
2. leading to ____ activation

Answer 25

1. acute phase proteins
2. complement

Question 26

cytokine ____ is a global suppressor of macrophage function

Answer 26

IL-10

Question 27

certain bacteria (superantigens) bind MHC II to ____ subunit of TCR without Ag present in peptide binding groove

cause unregulated release of cytokines → ____ shock

can lead to polyclonal ____ cell activation

Answer 27

beta

septic

T-cell

Question 28

red flags for superantigens:

1. staphylococcus
2. S. aureus
3. S. pyogenes

Answer 28

1. common in food poisening
2. toxic shock syndrome
3. streptococcal Tss or acute rheumatic fever)

Question 29

____ protrude through the capsular surface, enabling the adhesions to bind to host receptors yet keeping the bactyerial surface hidden

Answer 29

PILI

Question 30

the major mechanism used by bacteria to evade humoral immunity is variation of surface ____

Answer 30

Ags

Question 31

the innate immunity is mediated by phagocytes and NK cells interactions among which are mediated by ____ and ____. may control bacterial growth, but elimination of the bacteria requries adaptive immunity.

Answer 31

IL-12 and IFN-gamma

(IL-12 activates NK cells to release IFN-gamme to macrophages so they can kill ingested bacteria)

Question 32

the adaptive immunity is cell-mediated immunity in which ____ cells activate phagocytes to eliminate the microbes

Answer 32

T-cells

Question 33

M. Tuberculosis (an intracellular bacteria):

1. this bacteria invades macrophages and prevents lysosome from fusing with ____ → no phagolyosome
2. activates macrophages to produce ____ and activates T cells
3. CD4 T cells release ____ which recurits more macrophages and kills intracellular bacteria
4. CD8 respond to MHC I through cross-presentation and ____ the infected cells

Answer 33

1. phagosome
2. IL-12
3. IFN-gamma
4. kill

Question 34

intracellular bacteria evasion mechanisms:

1. inhibition of ____ formation
2. inactivation of ____ and ____
3. disruption of phagosome ____

Answer 34

1. phagolysosome
2. ROS and NOS
3. membrane

Question 35

role of Th1/Th2 cells in infection outcome:

1. Th1 cells:
2. Th2 cells:

Answer 35

1. activate phagocytes to kill ingeted microbes (classical macrophage activation)
2. which inhibit this classical pathway of macrophage activation (alternative macrophage activation)