Allergy Monday, January 6,2014
• 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 and immunity.
• If infection is working stronger than immunity, this can result in an allergic
• Allergies are abnormal sensitivities to antigens in the environment
• Allergens are antigens that cause allergies
• Allergens see ordinary substances as foreign, causing the immune system
• 2 types of allergies: seasonal and chronic
• Allergies are common in children, usually disappearing during teen years
and re-appear in adulthood
• Dust mites can be found everywhere. They can cause allergic reactions in
• 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) à B cells produce IgE against allergen à
IgE attaches to mast cells
Sensitization: First exposure to allergen
Allergens complex with IgE on mast cells à Mast cells release histamine and
other chemical à Blood Vessels dialate and release plasma
Reaction: Second exposure to allergen
Mast Cells Resting Mast Cell
Activated Mast Cell
Mast cells and Basophils
• Mast cells and basophils contain granules filled with inflammatory
chemicals such as histamine
• Sensitized cells bind IgE
• They are able to release the potent inflammatory mediators
• May be induced be 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
• Inhaled allergens may cause hay fever, an upper respiratory tract
• Marked by watery nasal discharge, sneezing, itchy throat and eyes, and
excessive tear production
• Commonly caused by mold spores, pollens, flowering plants, some trees,
and dust mites
• Examples include pinkeye, Allergic rhinitis, nasal polyps, tonsillitis, etc.
• Asthma is a result of genetics and environmental factors which make
certain people more susceptible to allergens. • Disorder of the obstruction of breathing
• Results in shortness of breath, wheezing (whistling sound)
• There is a strong genetic component to asthma. However, it takes more
than just genetics to have an attack.
o Inhaled allergens
Induces bronchial smooth muscle to over secrete mucus
and to contract
• Most of the times, asthma is a result of inhaled allergens.
• Due to release of histamine and other mediators into nearby skin
• Examples include eczema
• An estimated 1.5 million Americans have peanut allergies
• Peanut is the poster child of food allergies.
• There chemicals in peanuts that can cause very severe reactions.
• Vaccines against the flu contain traces of egg product, so if you are
allergic to eggs, another alternative might be suitable
Adverse Reaction to Food
Find out about this^^
*Lactose intolerance has nothing to do with allergic reactions
*10% of the world's population believes they have this unique allergic reaction,
however, it is actually intolerance
• Some foods may contain allergens
o Cause diarrhea, vomiting and other gastrointestinal signs and
o Can lead to an anaphylactic shock (people can be killed if they are
not taken care of quickly enough)
• Mainly (but not only) affect kids • Affects babies through breastfeeding
• Degranulation of many mast cells at once causes the release of large
amounts of histamine and inflammatory mediators
• Can result in acute anaphylaxis or anaphylactic shock
• Clinical signs
o Bronchial smooth muscles contracts violently
o Swelling of the larynx
o Leakage of fluid from blood vessels
Drop in the blood pressure
Treatment of Ana