​I. Allergic Rhinitis

​Rhino = nose; itis = inflammation

​Nasal inflammation

​aka Hay fever

​ -typically caused by allergens such as

hay, pollens, dust, spores of molds, etc.

​* if the main trigger is pollinating plants

​ -allergic rhinitis could flare up at specific times of the year (seasonal)

​Type 1 Hypersensitivity reaction: a type of reaction which starts with an exposure to an environmental allergen.

​Mechanism

​Dendritic cells--> T cells (activated)--> release cytokines

​ --> increased T cells --> stimulates B cells --> produces IgE antibodies

​ IgE antibodies--> released into the blood stream--> bind to mast cells (immune cells)

​

mast cells (carries histamines) --> once bound to IgE--> mast cells are primed

​

Primed: If pollen enters the body again in the future it degranulates which releases histamines to local tissues

Histamines: cause blood capillaries to dilate and become leaky which brings more fluid & immune cells to the area where mast cells are located

Eyes & Nose: portal of entry for infections;

lots of mast cells​ are surrounded in these areas for extra protection

​

​Diagnosis

1. ​Patch Test: Allergens are applied to patches & attached to skin

​* If skin becomes irritated when the patch is applied it suggest that you have an allergy to that particular substance.

​2. Scratch Test- A drop of allergen is placed on skin & pricked into the skin with a tool.

​* see if there is evidence for allergy, includes:

• ​raised bumps (weals)

• ​itchy red skin

​Patch test:

​Advantage: Can test many allergens at once

​Disadvantage:

​1) Low sensitivity:

No reaction to skin test but have reaction in nose & eyes

​2) Low specificity:

​ Have skin reaction to something but no reaction normally to allergen in their everyday life

​

​Treatment

• ​Avoid triggering allergen if possible

• ​If there are symptoms:

antihistamine medication can be used to suppress the mast cell degranulation

• ​Nasal irrigation:

can flush out the sinuses

​ which reduces the symptoms of allergic rhinitis