Innate Immunity

Question 1

Basic properties Of Innate Immune Defense

Answer 1

Provide physical and chemical barriers (epithelia and associated commensals)
Rely on phagocytosis
Produce inhospitable environment (granulocytes)

Question 2

Which type of immunity evolved first?

Answer 2

Innate Immunity before Adaptive Immunity

Question 3

Two Animal Classes with only Innate immunity

Answer 3

Echinodermata

Urochordata

Question 4

What do all innate immune defenses have in common

Answer 4

They rel on mechanisms that exist before the infection, are capable of responding rapidly to microbes, and react in the same way to repeat infections

Question 5

Hematopoietic Antigen Presenting Cells

Answer 5

Neutrophils
Monocytes
Macrophage
Dendritic Cell

Question 6

Hematopoietic Granulocytes

Answer 6

Eosinophil
Basophil
Mast Cell

Question 7

Non-hematopoietic Epithelia

Answer 7

Simple Squamous
Simple Cuboidal
Simple Columnar
Psuedostratified Columnar
Stratified Squamous
Stratified Columnar
Transitional

Question 8

Antimicrobial peptides (AMPs)

Answer 8

Antibiotic proteins secreted by epithelial cells - Targeted toward microbe-containing environment via secretory pathway

Question 9

Activity of AMPs

Answer 9

Small peptides that form pores through the membranes of multiple microbes including Gram (neg and pos) bacteria, fungi, protozoa and some viruses

Question 10

Defensins

Answer 10

AMPs produced by polymorphonuclear leukocytes

Question 11

Commensals (Associated with Epithelial Tissues)

Answer 11

1) Compete for resources with more virulent organisms
2) Produce their own AMPs
3) Keep innate immune cells in an “attentive” state
4) Lower vaginal pH

Question 12

Phagocyte Subsets (Circulating or Tissue Resident)

Answer 12

Neutrophil - Circulating
Macrophage - Tissue resident, but originally derive from circulating monocytes
Dendritic Cells - Tissue resident, but also monocyte derived (Langerhans cells - skin)

Question 13

PMNs (4 things)

Answer 13

First phagocyte to emigrate into an infected tissue
Short lived, dying within a few hours after reaching an infected site
Phagocytose microbes
Produce cytokines that attract other PMNs

Question 14

PMN actions to kill microbes (4)

Answer 14

1) Fusion with lysosomes which contain lysozyme, defensins, lactoferrin, hydrolases, and myeloperoxidase (MPO)
2) MPO catalyzes the production of HOCl from H2O and Cl-
3) NADPH oxidase dependent production of superoxide
4) Inducible nitric oxide synthase (iNOS) catalyzes formation of NO from arginine

Question 15

Macrophages

Answer 15

Tissue resident phagocytes that differentiate from circulating monocytes
“Activate” upon encountering a microbe

Question 16

PAMP

Answer 16

Pathogen associated molecular pattern (Macrophages)

Question 17

PRR

Answer 17

Pattern Recognition Receptors (Macrophages)

Question 18

Activity of Activated Macrophages (4)

Answer 18

1) Have recognized a PAMP through one or more PRRs
2) Have enhanced phagocytosis
3) Secrete pro-inflammatory cytokines
4) Couple phagocytosis to “antigen presentation” on MHC Class II molecules (Critical to adaptive immune response)

Question 19

The Coupling of phagocytosis to the Class II MHC Pathway

Answer 19

1) Peptides of varying length and sequence result from phago-lysosome digestion of microbes
2) These peptides accumulate in endocytic vesicles that fuse with Class II MHC containing vesicles
3) If Class II MHC binds one of the peptides, this complex moves to the cell surface where it can activate T-Cells

Question 20

Dendrites are similar to Macrophages

Answer 20

1) They are more efficient at processing phagocytosed microbes into antigens (Ag) for Ag-presentation
2) Dendrites extend from their cell body to increase the surface area available for MHCII: T-cell interactions
3) They are more efficient at migrating to the draining lymph nodes for Ag-presentation to adaptive immune cells

Question 21

DCs are referred to as immune sentinels for the following reasons (4)

Answer 21

1) Like macrophages, they constantly sample their environment
2) Unlike macrophages, DC’s migrate via the lymphatics to the draining lymph node
3) Once in the lymph node, DC’s come into greater contact with T and B cells, initiating the adaptive immune response
4) In addition to expressing high levels of MHCII, DCs increase their expression of co-stimulatory proteins

Question 22

Co-Stimulatory proteins associated with Dendritic cells

Answer 22

CD80, CD86, CD40

Question 23

Why don’t phagocytes defend against pathogenic helminths?

Answer 23

They are too big to be phagocytosed

Question 24

Three types of Granulocytes

Answer 24

Eosinophils
Basophils
Mast Cells

Question 25

Granulocyte Qualities

Answer 25

1) Non-phagocytic
2) 3 types of Granulocytes are more similar to one another than the 3 types of phagocytes
3) Defend their host by releasing granule contents into the extracellular space (Degranulation)
4) Activated by Ag-bound IgE binding cell surface FceRI

Question 26

Granule Secretions

Answer 26

Cytokines
Leukotrienes
Prostoglandins

Question 27

Granule Exocytosis

Answer 27

Proteases - Disrupt parasite tegument (link to host)
Vasoactive amines (Histamine) - promote parasite expulsion from gut