Lecture 20

Question 1

What is the function of CRP and SAP?

Answer 1

Acute phase proteins (APPs) that bind to bacterial surfaces (phosphocholine), bind to globular heads of C1q and activate classical complement pathway

Question 2

Which complement pathways are activated by lipopolysaccharides?

Answer 2

Alternative and classical

Question 3

What do C3a and C5a do?

Answer 3

Bind to receptors on mast cells and activate them

Question 4

What do activated mast cells do?

Answer 4

Degranulate, releasing large amounts of histamine and bradykinin that enhances blood flow; causes arteriolar vasodilation, venous constriction in some vascular beds, and increased capillary permeability; increased blood flow and local edema are perceived as itchiness and irritation

Question 5

What is the first cell to release cytokines and chemokines?

Answer 5

Mast cells

Question 6

What are the potent neutrophil chemoattractants?

Answer 6

C5a, C3a, IL-8/CXCL8

Question 7

What do immature DCs do during an extracellular bacteria infection?

Answer 7

Engulf and internalize bacteria (Ags) via PRRs (TLRs)

Question 8

What do activated DCs do during an extracellular bacteria infection?

Answer 8

Migrate to local LNs via lymphatics

Question 9

What causes the swelling and local hyperemia in LNs?

Answer 9

Lymphocytes become trapped, activated, and proliferate in inflamed LNs

Question 10

What is responsible for the homing of lymphocytes to LNs?

Answer 10

L-selectin on lymphocytes and PNaD (peripheral lymph node addressin) on HEVs

Question 11

Infections caused by pathogenic extracellular bacteria have 2 principle mechanisms. What are they?

Answer 11

1. Tissue damage is caused by inflammation at the site of infection
2. Bacteria produce toxins which have diverse pathologic effects

Question 12

Define endotoxins and exotoxins

Answer 12

Endotoxins: components of bacterial cell walls

Exotoxins: secreted by bacteria

Question 13

What is the function of Th17 cells? What effect do genetic defects in Th17 development have?

Answer 13

Promote local inflammation and recruit neutrophils and monocytes at sites of bacterial infection; genetic defects result in increased susceptibility to bacterial and fungal infections, with formation of multiple skin abcesses

Question 14

Define septic shock and septic shock syndrome?

Answer 14

Septic Shock: severe pathological consequence of disseminated bacterial infection (sepsis) by some gram-negative/positive bacteria

Septic Shock Syndrome: characterized by circulatory collapse and disseminated intravascular coagulation

Question 15

What is the main function of IL-10?

Answer 15

Major suppressor of macrophage function

Question 16

Explain bacterial superantigens?

Answer 16

Bind to class II MHC outside the peptide-binding groove and bind to the variable region of different TCR-beta chains, regardless of the peptide specificity; therefore, superantigens can activate a large number of T cells causing polyclonal T cell activation

Question 17

What is Kawasaki disease?

Answer 17

Acute, multi-system vasculitis of unknown etiology; evidence suggests that it is a superantigen mediated disease

Question 18

What is the endogenous pathway of antigen presentation?

Answer 18

Proteins from intracellular pathogens are degraded by the proteasome and the resulting peptides are shuttled into the ER by TAP proteins; these peptides are loaded onto MHC class I and then delivered to the cell surface

Question 19

What is the exogenous pathway of antigen presentation?

Answer 19

Extracellular pathogens are engulfed by phagosomes; inside the phagosome, the pathogen-derived peptides are loaded onto MHC class II molecules, which activate Th cells that stimulate the production of Abs

Question 20

What is responsible for the detection of beta-glucan?

Answer 20

Dectin-1

Question 21

What is the major receptor involved in the nonopsonic recognition of fungi?

Answer 21

Macrophage mannose receptor