This document discusses hypersensitivity type I, also known as an immediate hypersensitivity reaction. It involves an antibody-antigen reaction where IgE antibodies bind to mast cells and basophils. When a sensitized individual is re-exposed to an allergen, it cross-links the IgE and causes degranulation and release of inflammatory mediators like histamine. This leads to symptoms like smooth muscle contraction and vasodilation. Treatment involves corticosteroids, antihistamines, and epinephrine. Hypersensitivity type I can lead to diseases like asthma, allergic conjunctivitis, and angioedema and has no cure but can be managed.

1. HYPERSENSITIVITY I
GROUP SEVEN
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2. GROUP MEMBERS
• MICHAEL MENSAH
• DEKYI REUBEN
• NYARKO PRINCE
• EDEM KOJO JOHN
• BUABENG ISAAC KOJO
• CARR JEREMIAH
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3. OBJECTIVES
• Facts and what hypersensitivity I is.
• What is its pathophysiology or mode of work?
• Who is susceptible to the disease ?
• Treatment and prognosis.
• Examples of diseases under hypersensitivity I.
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4. FACTS ON HYPERSENSITIVITY I
• Hypersensitivity I has no cure, but can be managed.
• The cost of treatment and management of hypersensitive
patients costs over $18 billion dollars annually.
• With food allergy treatment alone costing about $25 billion
dollars annually.
• In the US, 50 million people experience various types of
allergies under hypersensitivity I each year.
• It is also known as immediate hypersensitivity.
• It is an immune allergic response.
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5. PATHOPHYSIOLOGY OF HYPERSENSITIVITY
I
• The difference between hypersensitivity I and other
immune response is the production of IGE instead of
IGM, IGG or IGA.
• In hypersensitivity I or immediate hypersensitivity,
there is an antibody-antigen reaction where B-cells are
made to produce immunoglobulin-E (IGE) antibodies
by CD4+ and TH2 cells.
• In this antibody-antigen reaction, Immunoglobulin-E
antibodies bind to FCᵋRI receptors on the surface of
tissue mast cells and blood basophils.
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6. PATHOPHYSIOLOGY OF HYPERSENSITIVITY
I
• Antigens found in this particular
reaction are known as Allergens.
• These allergens may enter the body by
injection, ingestion, inhalation or
through direct contact or exposure.
• After these allergens have binded to the
receptors, the body becomes ‘sensitized’
upon the first exposure.
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7. PATHOPHYSIOLOGY OF HYPERSENSITIVITY
I
• Upon second exposure after sensitization has occurred,
there is the cross-linking of the IGE bounded on the
sensitized cells and the resulting effect being
anaphylactic degranulation.
• Where pre-formed active mediators from storage
granules are released immediately and explosively.
• There is the concurrent synthesis of lipid mediators
from arachidonic acid.
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8. PATHOPHYSIOLOGY OF HYPERSENSITIVITY
I
• The release of these mediators are to cause smooth-
muscle contraction and vasodilation.
• They include histamine, leukotriene (LTD4, LTB4 and
LTC4) and prostaglandin ( which acts on proteins
located in surrounding tissue)
• Hypersensitivity I is classified into two phases of
response being the immediate phase and late phase.
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9. PATHOPHYSIOLOGY OF HYPERSENSITIVITY
I
• The Immediate phase being the release of vasoactive
amines and lipid mediators within a matter of minutes
or seconds.
• And the late phase being the release of the mediators as
well as cytokines within 2-4 hours.
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10. PATHOPHYSIOLOGY OF HYPERSENSITIVITY
I 10

11. SUSCEPTIBILITY OF DISEASE CONDITION
• There is actually no age limit for susceptibility for
hypersensitivity I.
• It is estimated that children between the ages of 0-4
years are more prone to developing diseases involving
hypersensitivity I.
• It also estimated that elderly people or persons are also
susceptible to diseases involving hypersensitivity I.
• Generally persons with somewhat weak immunologic
response are susceptible to developing such disease
conditions.
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12. TREATMENT AND PROGNOSIS
• The treatment or otherwise management of the
condition includes the use of
corticosteroids,antihistamine and adrenaline in
controlled doses.
• In prognosis, hypersensitivity can lead the body to
reactive negatively to certain actions and substances. It
can lead to severe allergic reactions in a form of
response. Such responses include,
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13. ASTHMA 13

14. ALLERGIC CONJUCVITIS 14

15. ANGIOEDEMA 15

16. OTHER ALLERGIC RESPONSES 16

17. OTHER ALLERGIC RESPONSES 17

18. REFERENCES
• 2011, Shiv Pillai MD, Abdul K. Abbas MBBS; Andrew Wilson.
“Cellular and Molecular Immunology: with STUDENT
CONSULT online access. Philadelphia
• 2018, Article- CDC National Centre for Health Statistics.
FastStats: Allergies and Hay fever.
• GETTY IMAGES
• 2018, Article- American College of Allergy, Asthma and
Immunology. Allergy Facts.
• immunology-kuby, pg. 20, introduction.
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