Immunology of infectious Disease

Question 1

What are the features of Extracellular Bacterial infections?

Answer 1

Multiply outside the host cell
Tissue Destruction
Induce inflammation!
Toxins that kill host cells 
Immunity by killing EC bacteria and neurrialize toxin

Question 2

How does the innate immunity deal with EC bacteria?

Answer 2

Phagocytosis= first line of defense
Neutrophils in Blood
Macrophages in tissue
Pahgocytes recognize bacterial structures(polysaccharides, peptides,
Fc Receptors and C3b receptors to bind IgG and C3b
Phagocytes remove bacteria in the lymph nodes and the spleen

Question 3

What are examples ofExtracellular Bacteria?

Answer 3

Staph, strep, Neisseria, E coli, Clostridium

Question 4

What is the first immune cell to arrive at the site of infection?

Answer 4

Neutrophils.

Question 5

What are the most important opsonins?

Answer 5

C3b and IgG

Question 6

WHat is the Fe binding molecule that keeps it from bacteria?

Answer 6

Lactoferrin

Question 7

What activates the Alternative pathway of compliment activation?

Answer 7

Peptidoglycan and LPS

Leads to lysis or opsinization

Question 8

What complement deficiencies lead to Neisseria Infections?

Answer 8

C5-C9 dificiencies

Question 9

What is the effect of Complement on G- and G+ bacteria?

Answer 9

Lyses G- Bacteria

Opsonizes G+ bacteria

Question 10

How does Adaptive immunity attack extracellular bacteria?

Answer 10

IgG opsonizes and enhances Phagocytosis
Toxin specific Ab neutralizes toxins
IgM and IgG activate classical complement => Lyse Bacteria

Question 11

What Immunoglobulin can cross the placenta?

Answer 11

IgG

Question 12

What type of infections is baby vulnerable to at 6 mo old?

Answer 12

S. Pneumo
N meningiditis
H. influenzae B

Question 13

What Bacteria produce M protein? What does it do?

Answer 13

S. Pyogenes and S. Pneumo

Many forms mean that one type of Ab may not work against next infection

Question 14

What is the Ig at Mucosal sites?

Answer 14

IgA

Fixes Comlement

Question 15

What happens to a Pt that is Deficient in IgA?

Answer 15

IgM Ab can compensate

Can be more suceptible to URT infections (mucosa)

Question 16

How do EC bacteria evade immunity?

Answer 16

Polysaccharide capsule
Variation of surface antigen
IgA Protease(Neisseria and Hemophilus)
Interfere with complement activation(S. Pyogenes, S pneumo)
S. Typhi => Type 3 secretion system

Question 17

What are the bad effects of the Immune response?

Answer 17

Septic Shock: HypoTn and DIC

Superantigens

Question 18

What are the disease Causing Ab?

Answer 18

Rheumatic Fever

Post Strep glomerulonephritis

Question 19

What Bacteria are included in Spirochetes?

Answer 19

Treponema Pallidum
Borrelia Burgdorpheri
Leptospira

Question 20

What are features of Spirochete Infections

Answer 20

Cant penetrate unbroken skin
Arthropod vectors
Local Multiplication
Periods of latency

Question 21

How does the immune system fight Spirochete infections?

Answer 21

Neutrophils, Phago
ADAPTIVE better
T pallidum => strong cell mediated and humoral immunity
Th1
Ab => opsonzation + protective immunity after latent syphilis
Classical compliment for Borrelia

Question 22

How does T pallidum evade immunity

Answer 22

lacks virulence factors

Hard to kill

Question 23

How does B Burgdorpheri evade immunity

Answer 23

Coats with amorphous host material => prevents phagocytosis and complement andevades adaptive imm.

Question 24

What are the bad effects of immunity to Spirochetes?

Answer 24

2^ syphilis###

Question 25

How does the innate immune system fight Fungi?

Answer 25

Neutrophils

Phagocytosis

Question 26

How does the adaptive immune system fight Fungi?

Answer 26

Th1 mediated immunity
Crypto = CTL elimination
Intracellular fungus Histo => granulomas
Antibodies to Candida

Question 27

What cells are present in granulomas?

Answer 27

Mycobacteria (inside macrophages)
Multi-nucleated giant cells
epithelioid cell
T cells (outer layer)

Question 28

How does the adaptive immunity fight Parasites?

Answer 28

IgE production

• Mast cells release histamine
• triggers vomiting

Question 29

What is the difference between Th1 and Th2 mediated immune response?

Answer 29

Th1: CTLs, Macrophage-mediated killing and/or IgG
Th2: IgE and infiltration by eosinophils
Cytokines downreg opposing response

Question 30

What are rhe evasion strategies that Parasites use?

Answer 30

Concealment
Coats with host protein
Outer surface inhibits complement, repairs damage
Ez cleaves membrane bound Ab

Question 31

What are rhe bad effects of immunity to parasites?

Answer 31

Malaria increases TNF-a production

Chronic parasite infection = immune complexes = vasculitis and nephritis