EXAM #1: IMMUNOLOGY OF INFECTIOUS DISEASE Flashcards Preview

Infectious Disease > EXAM #1: IMMUNOLOGY OF INFECTIOUS DISEASE > Flashcards

Flashcards in EXAM #1: IMMUNOLOGY OF INFECTIOUS DISEASE Deck (44):
1

How do extracellular bacteria evade the immune system?

1) Induction of vigorous inflammation
2) Production of toxins that kill host cells

*So we try to kill the bacteria and neutralize the toxins

2

What is the major innate immune response against extracellular bacteria?

Phagocytosis via neutrophils (blood) and macrophages (tissue)

3

What is the first cell to arrive in acute inflammation?

Neutrophils

4

What do phagocytes recognize on extracellular bacteria?

Bacterial structure including:
1) Polysaccharides
2) Peptides (RGD sequence)

5

What is the main immunologic responder to blood-born pathogens?

Spleen

6

What is the main immunologic responder to tissue-born pathogens?

Lymph nodes

7

What is the role of unmethylated CpG dinucleotide motifs in the immune system?

Activation of macrophages

8

What metal is required for many bacteria to survive?

Iron

9

What is MOA of lactoferrin? What cell releases lactoferrin?

- Neutrophils
- Lactoferrin lowers iron concentrations (starves bacteria of iron)

10

What does a deficiency in C5-C9 lead to?

Susceptibility to N. meningitidis infection

11

What is the principal immune defense against extracellular bacteria?

Humoral immunity i.e. antibodies

12

How does humoral immunity combat extracellular bacterial infection?

1) IgG opsonization
2) Toxin-specific antibody neutralization
3) IgM and IgG activate classical complement pathway

13

What infections are neonates susceptible to as maternal antibodies disappear?

- S. pneumoniae
- N. meningitidis
- H. influenzae

14

What antibody can opsonize bacteria at mucosal sites?

IgA

15

What is the most common immunodeficiency?

Selective IgA

*Note that IgM can compensate

16

What complement pathway is specifically inhibited by a polysaccharide capsule?

Alternative pathway

*Note that IgG and C3b can bind and opsonize these bacteria for elimination

17

What organism drastically alters its surface adhesion proteins?

Neisseria

18

What organisms can produce IgA1 protease?

1) S. pneumoniae
2) Neisseria
3) Hemophilus

19

How does S. pyogenes evade immunity?

Interferes with complement activation via M proteins

20

How does S. pneumoniae evade immunity?

C3 protease

21

How does S. typhi evade the immune system?

Type III secretion system

*Prevents NFkB mediated signaling and secretion of TNF-a

22

What organisms are most associated with septic shock?

Gram negative

23

What cytokines mediate septic shock?

TNF-a
IL-1

24

What are superantigens?

- Toxin that binds Class II MHC on APCs and T-cells
- Causes the production of TNF-a

25

What causes Rheumatic Fever?

Cross-reactive antibodies induced by strep M-protein

26

What causes poststreptococcal glomerulonephritis?

Antibodies form immune complexes that deposit in the kidney

*Type III hypersensitivity

27

What are the three major spirochetes?

1) Treponema pallidum (Syphillis)
2) Borrelia burgdorferi (Lyme)
3) Leptospira

28

How do spirochetes enter the body?

Broken skin or vector

*Cannot penetrate intact skin

29

What is the major mechanism of immunity against spirochetes?

Adaptive immunity

*Note a very good response from innate immunity

30

What is the role of cell-mediated immunity (Th1) in spirochete infection?

Clearing infection

31

What is the role of humoral (Th2) immunity in spirochete infection?

Protection against reinfection

32

How does T. pallidum evade the immune system?

Lacks virulence factors ; is simply very resistant to normal host mechanisms

33

How does B. burgdorferi evade the immune sytem?

Coats self with amorphous host material

34

What are the manifestations of an overzealous immune response against spirochetes?

1) Rash of secondary syphilis is Type III hypersensitivity reaction
2) Lyme arthritis is caused by T-cells

35

What is the major innate immune response to fungal infections?

Neutrophils

*Note that neutropenic patients highly susceptible to C. albicans

36

What is the major adaptive immune response to fungal infections?

Cell mediated immunity (Th1)

*Can lead to granuloma formation

37

What is the major immune response to helminth/worm infections?

IgE production (Th2)

38

What are the major adaptive immune responses to protozoa (Leshmania and Trypanosoma)?

These organisms infect macrophages and produce a Th1 response

39

What happens after macrophages are exposed to IFN-gamma?

1) NO production
2) Depletion of intracellular tryptophan that is essential for some parasites

40

What is the major immune mechanism against Plasmodium?

Th1, CTLs against intrahepatic stage

41

What is the major deletarious effect of the immune response to Plasmodium?

High levels of TNFa production

42

What strategies do parasites use to evade the immune system?

1) Conceal in intestinal lumen
2) Coat with host proteins
3) Inhibition of complement activation
4) Production of enzymes that cleave membrane bound antibodies

43

What is a high level of TNF-a production in childhood malaria infections prognostic for?

Death

44

What do you need to remember about vaccines and parasite infected areas?

- Vaccines= Th1 immune response
- Chronic parasite infestation can induce strong Th2 response

*Thus, b/c of the reciprocal relationship between these two immune reactions, vaccines may not be as efficacious