Allergies are abnormal immune responses to harmless antigens called allergens. There are four main types of hypersensitivity reactions including type I immediate allergic reactions. Symptoms can range from mild local reactions to life-threatening anaphylaxis. Diagnosis involves clinical history, skin prick tests, blood tests for allergen-specific IgE. Treatment depends on severity but may include allergen avoidance, antihistamines, epinephrine injections, immunotherapy. Epinephrine is the first-line treatment for anaphylaxis as it counters hypotension, bronchospasm and mast cell degranulation.

1. Allergies
Prof. Dr. Ahmed Mohammed Salih
Professor of Molecular Microbiology & Immunology
PhD (MM), M.Sc. (MMM), M.Sc. (Immuno.)
College of medicine
University of Duhok

2. Aims
-Define the allergy
-Types of hypersensitivity reactions
-Clinical manifestations
-Causes
-Mechanism of allergic reactions

3. Clinical case
A 55 year old bee-keeper was stung by a bee, and shortly
afterwards developed wheezing, difficulty breathing.
He became light-headed and lapsed into unconsciousness.
An ambulance was called, and the paramedic found that his blood
pressure was 80/40 and the presence of swollen face and
generalized skin rash.
A anaphylactic reaction was diagnosed and the patient was given
immediately im of epinephrine.
Trigger? Timing?
Symptoms
• Respiratory S.
• Cardiovascular S.
• Skin
• Face
Therapy
Unfortunately the patient did not respond and shortly died after
another im injection.
He had received a bee sting about two years previously, but on
that occasion had made only a local reaction to the sting.
Why?
Outcome

4. Bee stings cause Hypersensitivity Reaction
(Allergic reactions)
The term hypersensitivity describes “the
antigen-specific immune responses that are
either inappropriate or excessive and result in
harm to host”
The mechanisms underlying these aberrant
immune responses are the same those
employed by the host to fight infections

5. Common feature of hypersensitivity
reactions
• Sensitization phase
 First encounter with the antigen (allergen)
• Effector phase
 Clinical pathology upon re-exposure to the
same antigen

6. Types of Allergic reactions due to
stings:
Mild reaction
Most of the time, bee sting symptoms are minor and
include:
- Instant, sharp burning pain at the sting site
- A red welt at the sting area
- Slight swelling around the sting area
In most people, the swelling and pain go away within a
few hours.

7. Moderate reaction
Some people who get stung by a bee or other insect
have a bit stronger reaction, with signs and symptoms
such as:
Extreme redness
Swelling at the site of the sting that gradually enlarges
over the next day or two
Moderate reactions tend to resolve over five to 10
days.

8. Severe allergic reaction
A severe allergic reaction (anaphylaxis) to bee stings is
potentially life-threatening and requires emergency
treatment. A small percentage of people who are stung
by a bee or other insect quickly develop anaphylaxis.
Signs and symptoms of anaphylaxis include:
- Skin reactions, including hives and itching and
flushed or pale skin
- Difficulty breathing
- Swelling of the throat and tongue
- A weak, rapid pulse
- Nausea, vomiting or diarrhea
-Dizziness or fainting
-Loss of consciousness

9. Some allergic reactions develop to (Anaphylaxis):
Anaphylaxis is a severe, potentially life-threatening
allergic reaction. It can occur within seconds or minutes of
exposure to allergen, such as peanuts or bee stings.

14. Melittin is the main component (40–60% of the dry weight) and the major pain producing
substance of honeybee.It has strong surface effects on cell membranes causing pore-
formation in epithelial cells and the destruction of red blood cells. Melittin also
activates nociceptor (pain receptor) cells through a variety of mechanisms.

16. Types of hypersensitivity reactions
• Type I or immediate (<30min): Allergies
 Environmental non infectious antigens (allergens)
• Type II or antibody mediated (5-12hr)
• Type III or immune complexes mediated (3-8hr)
• Type IV or cell mediated (24-48hr)
 Environmental infectious agents and self antigens

17. Why do people have allergies?
Farmer
City people

18. Why do people have allergies?
TH2 (Lymphocyte)
phenotype
IgE production
TH1 (Lymphocyte)
phenotype
Atopy

19. Common allergens
• House dust mite, cockroaches
• Animals, especially domestic pets such as
cats and dogs
• Tree and grass pollens
• Insect venom such as that contained in
wasp and bee stings
• Medicines - for example, the antibiotic
penicillin.
• Chemicals such as latex
• Foods, such as milk, peanuts, nuts, etc... Wikipedia
Wikipedia

20. Mast cell mediators

21. Immune mechanism of allergic reaction
Diagnosis
Blood/serum levels of
mast cell products
Allergen 2nd exposure (min)
Allergen 1st
exposure

22. Skin manifestation of allergic reactions
Urticaria
Mast cells in the epidermis

23. Angioedema
lip, eyes, tongue and
upper respiratory airways
Mast cells in the deep
dermis
Wikipedia
Faces manifestations of allergic reactions

24. Systemic manifestations of allergic
reaction: anaphylaxis
Systemic activation of
mast cells
Hypotension
Cardiovascular collapse
Generalized urticaria
Angioedema
Breathing problems
Systemic absorption of the
allergen

25. Clinical case
A 55 year old bee-keeper was stung by a bee, and shortly
afterwards developed wheezing, difficulty breathing.
He became light-headed and lapsed into unconsciousness.
An ambulance was called, and the paramedic found that his blood
pressure was 80/40 and the presence of swollen face and
generalized skin rash (hives).
A anaphylactic reaction was diagnosed and the patient was given
immediately im of epinephrine.
Systemic
introduction of the
allergen
Immediate type 1
Hypersensitivity reaction
Mast cell activation
in the lung
 and  receptors
Unfortunately the patient did not respond and shortly died after
another im injection.
He had received a bee sting about two years previously, but on
that occasion had made only a local reaction to the sting. Was not sensitized
to the allergen
Mast cell activation in
dermis and deep dermis
Effect of
vasculature

26. Treatment of anaphylactic shock :
epinephrine (adrenaline) IM
!!!!
Monitor pulse, blood pressure, ECG, oximetry
DO NOT DELAY
www.medscape.com
• Reverses peripheral vasodilation and reduces oedema
and alleviates hypotension
• Reverses airway obstruction / bronchospasm
• Increases the force of myocardial contraction
• Inhibits mast cell activation
http://www.resus.org.uk/

27. Adrenaline
As a hormone, adrenaline acts on nearly all body tissues.
Its actions vary by tissue type and tissue expression
of adrenergic receptors. For example, high levels of
adrenaline causes smooth muscle relaxation in the
airways but causes contraction of the smooth muscle that
lines most arterioles.

28. Epinephrine is the medication of choice for the
first-aid treatment of anaphylaxis. Through
vasoconstrictor effects, it prevents or decreases
upper airway mucosal edema (laryngeal edema),
hypotension, and shock. In addition, it has
important bronchodilator effects and cardiac
inotropic and chronotropic effects.

31. Key points about epinephrine
therapy
• Time saver vs lifesaver
• IM vs SC administration
• Multiple doses may be required
• Proper use of epipen
• Letters / Ann Allergy Asthma Immunol 114 (2015) 63e76

32. Common allergic diseases

33. • Clinical history
– Atopy, allergens, seasonality and route of exposure
• Blood tests
– Serum allergen-specific IgE
– Serum mast cell tryptase, histamine (systemic
degranulation)
• Skin prick tests (range of allergens)
– Wheal and flare reaction (> 3mm)
– !!!! No antihistamines
• Challenge tests: food and drug allergy
– !!!! Slight risk of anaphylaxis in highly sensitized patients
Diagnosis of allergy

34. Skin prick test for allergy
Mast cells in the epidermis
Wheal and flare reaction
Needs trained personnel
Risk of anaphylaxis in
highly sensitive subjects

35. • Allergen avoidance/elimination
– Read food labels
– House dust mite avoidance
– Avoid high risk situations
• Education
– Parents to recognize symptoms
– Patients to use EPIPEN
– Call Emergency services when EPIPEN used
– Schools and social activities
• Medic alert identification
Management of allergy
Wikipedia

36. • Drugs
– Anti-histamines: Alternate sedating/non-
sedating forms
– Corticosteroids (topical, systemic)
– Anti-IgE IgG (Omalizumab)
– Anaphylaxis: Injectable adrenaline 0.5 mg
(Epipen, i.m.)
• Allergen desensitization
– Patients with high risk of systemic attacks
– !!!! specialist hospital based-unit with
resuscitation equipment
Management of allergy
Leonard Noon
wikipediacom

37. Allergen desensitization or
immunotherapy
Definition
“It involves the administration of increasing doses of allergen extracts
over a period of years, given to patients by injection or drops/tablets
under the tongue (sublingual)”
90% effective in patients with bee and wasp venom anaphylaxis
Potential mechanisms
• CD4+CD25 Regulatory T cells
• Shift from TH2 to TH1
• Inhibitory anti-inflammatory cytokines
• Allergen specific blocking IgG