Allergic reactions are the evil part of the immune system.
Your immune system is usually working well if it is in some sort of balance between infection
If infection is working stronger than immunity, this can result in an allergic reaction.
• Allergies are abnormal sensitivities to antigens in the environment
• Allergens are antigens that cause allergies
Dust mites can be found everywhere. They can cause allergic reactions in some people.
The allergic reaction of these takes place in a very unique time of the year. It is seasonal.
Development of Allergic Reaction
Typical allergic reaction
Tissue contact with allergen (antigen) B cells produce IgE against allergen IgE attaches to
Sensitization: First exposure to allergen
Allergens complex with IgE on mast cells Mast cells release histamine and other chemical
Blood Vessels dialate and release plasma
Reaction: Second exposure to allergen
Resting Mast Cell
Activated Mast Cell
Mast cells and Basophils
• Mast cells and basophils contain granules filled with inflammatory chemicals such as
• Sensitized cells bind IgE • They are able to release the potent inflammatory mediators
• May be induced by aggregation of IgE bound to high-afinity receptors (Fc receptors) on
the surface of these cells
• Specific antigen (allergen) is responsible for the IgE aggregation.
Clinical Signs of Localized Allergic Reactions
• The hypersensitivity reactions are usually mild and localized
• Site of the reaction depends on the portal of entry
o Inhaled allergens may cause hay fever, an upper respiratory tract response
Marked by watery nasal discharge, sneezing, itchy throat and eyes, and
excessive tear production