Case 19
Zeb Pike, Leia King, Mary Currier,
Ashley Sherertz, and Manuella De
Garret Danigan - 27 year old man
● Awoke to hand shaped rash on leg
● One week earlier - received mangos and
rested his hand on his leg while peeling
the fruit
● Contact Dermatitis
Contact Dermatitis
● More than 3 million
cases in the U.S.
● Skin rash caused
by contact with a
certain substance
or irritant
Test and Diagnosis
Identifying what's causing symptoms and
figuring out whether you have the irritant or
allergic type
● A thorough medical history
and physical exam
● A patch test - contact
delayed hypersensitivity
allergy test
Patient History
A previous occurrence of the rash happened
during a summer a few years earlier
● On hands, arms, and legs
● Most likely due to poison ivy
Past Summer Exposure
● Benadryl - not effective
● One week of corticosteroids cleared up
the contact dermatitis
Used when the body’s immune system
causes an unwanted response
● Lessen inflammation by limiting the
amount of inflammatory signals that cells
can produce
● Inhibit cell proliferation
Can be taken by:
● Mouth - Help treat inflammation associated with
chronic conditions
● Inhaler or intranasal spray - Control
inflammation associated with asthma and nasal
● Topically - Help heal skin conditions
● Injection - Help treat inflammation of tendinitis
● Antihistamine
o blocks the action of
histamine in the
o helps to relieve the
● Was ineffective
More Recent Response from Mangos
● The most recent rash
● Exposure to the mango peel
o Caused delayed contact dermatitis
Type IV Hypersensitivity
● “Delayed hypersensitivity reaction”
● First, local immune response to foreign
o Increase endothelial cell adhesion molecule
expression → leukocyte accumulation at
tissue site
● Antigen engulfed by macrophages and
Type IV Hypersensitivity
● Antigen presented to specific T-cell receptor
● Macrophages → secrete interleukin and
lymphokines → form giant cells
● Interleukins mediate communication
● Activation of cytotoxic T-cells is possible
● Key mediators:
o CD 4+ Helper T-cells
o CD8+ T-cells
Type IV Hypersensitivity
What is different about Type IV
hypersensitivity reactions when
comparing to the other types?
Immune Response - Type IV Hypersensitivity - Delayed Type [HD Animation]
Question 1
Type IV hypersensitivity responses to poison
ivy result in damage to the skin at the point
of contact. What type(s) of cells are
responsible for this damage?
Question 1
Cytotoxic T-cells and macrophages can
respond to affected areas when activated by
an APC
● Cytotoxic T-cells
○ respond to target cells
● Macrophages
○ manufacture large amounts of hydrolytic
○ responds in a less specific target approach
Question 2
Why did the patient have the same type of
response to both poison ivy and mango
Question 2
● Mangos and poison ivy belong to the
same plant family, Anacardiaceae
● Both poison ivy and mango trees create
o Urushiols cause irritation upon contact
● Organic allergen
● Mango flesh - very low levels of
● Most sensitive people can eat
the fruit without problem as long
as someone else peels it
Question 3
How is a Type IV hypersensitivity different
from an allergy (Type I hypersensitivity)?
Question 3
Type 1 (immediate) - response caused by the IgE
mediated response of histamine released by mast
cells and basophils
Type 4 (delayed) - T- cell mediated response and
occurs by CD4+ cells and Th1 cells releasing
cytokines to attract CD8+ cytotoxic T-cells to
destroy marked cells.
Question 4
Why were corticosteroids effective as
treatment in the case while Benadryl was
Question 4
Benadryl is an antihistamine
● Does not affect the rash due no histamine
being produced
● Type 4 hypersensitivity does not trigger
mast cells or basophils
● Treatment for that kind of immune
response does not work