#7 - Type I Hypersensitivity

Question 1

TfH cell role in type I hypersensitivity

Answer 1

Antigen exposure
↓
TfH
↓
IgE class switching
↓
IgE binding FcεRI on mast cells
↓
Degranulation
↓
Immediate hypersensitivity

Question 2

Dust mites and pollen hypersensitivity

Answer 2

Dust mites + pollen
↓ (TLR4, PARs, ROS)
DC
↓
Allergic rxn

Question 3

Whats TLR4?

Answer 3

Co-receptor for MD-2 (Mimiced by “Der-p2” which is within dust mites), detects LPS (Gram neg.)

Question 4

Whats PARs?

Answer 4

Allergens are proteases; when PARs are cut, it activates DCs

Question 5

Role of ROS in pollen/dust mites

Answer 5

ROS is released by pollen when hydrated (tears, nasal discharge), and it’s a DAMP, activating DCs

Question 6

Alarmins activating DCs

Answer 6

Stressed epith.
↓
IL-1α
HMGB-1
Uric Acid
ATP
(ALARMINS)
↓
DCs

Question 7

Physical effects of IgE-mediated mast-cell degranulation within different tissue exposed to an allergen

Answer 7

Gastro THINK DIARRHEA
1. Inc. fludi secretion
2. Inc. peristalsis

Airways THINK ASTHMA
1. Dec. diameter
2. Inc. mucus secretion

Vascular THINK HISTAMINE EFFECTS
1. Inc. blood flow
2. Inc. permeability