Download Skin test

Patch Test
By H.Eshaghi M.D
IRRITANT CONTACT DEMATITIS
 Non-immunologic inflammatory reaction of the skin
due to an external agent
 Varied morphology
 Clinical types
 Chemical burns
 Irritant reactions
 Acute irritant contact dermatitis
 Chronic irritant contact dermatitis
Irritant Contact dermatitis :
Acute irritant dermatitis → severe eczematous reaction
 Single overwhelming exposure
 Few brief exposures to strong irritants or a caustic agent
Chronic (cumulative) irritant dermatitis → eczematous
changes that develop upon repeated exposure to weaker
irritants:
water, soaps, detergents, solvents, weak acids or
alkalis, low humidity, heat, air, and dusts
Allergic Contact Dermatitis
 Delayed type IV hypersensitivity reaction
 SENSITIZER: chemical agent with low molecular weight
which is able to sensitize certain individuals and induce cell
mediated immune reaction that end with dermatitis only
in previously sensitized persons.
 Pathogenesis:
 Induction (sensitization) phase: 18-24 days
 Elicitation phase: 2-4 days
 Antigen binds Langerhan’s cells in the epidermis or
macrophages in the dermis
 Interaction with CD4+ T lymphyocytes at the regional
lymph nodes causes release of inflammatory
cytokines
Mechanism
 Specific immune phenomenon that is the result of
a T cell mediated immune response to a defined
allergen resulting in eczema or the exacerbation of
a pre-existing dermatitis
Common allergens
Chromate
Rubber chemicals
Preservatives
Nickel
Fragrances
Epoxy resins
Phenol-formaldehyde resins
 Contact dermatitis of the
hands in a dental
technician
 Patch testing to be allergic
to the Thiuram chemicals
(accelerator in gloves)
Theoretical basis of patch testing
Patch test was first devised by
Jadassohn(1895) and described in practical
detail by Bloch (1929) immunological basis of
the patch test is the type IV.
Hypersensitive Reactions
1. Type I Hypersensitivity
2. Type II Hypersensitivity
3. Type III Hypersensitivity
4. Type IV Hypersensitivity
Components and cells in Type I hypersensitivity
Allergen ：
pollen、dust mite、insects, etc
selectively activate CD4+Th2 cells and B cells
Allergen（IgE）and its production
IgE： mainly produced by mucosal B cells in the lamina prapria
special affinity to the same cell
IL-4 is essential to switch B cells to IgE production
High affinity receptor of the IgE on mast cell and
basophil
Type I hypersensitivity
Type I hypersensitivity
Common disease of type I hypersensitivity
Systemic anaphylaxis:
1) Anaphylactic drug allergy ：penicillin
2) Anaphylactic serum allergy ：
 Respiratory allergic diseases :
1) Allergic asthma
 2) Allergic rhinitis
 Gastrointestinal allergic diseases :
The lack of Serum IgA protein hydrolase
 Skin allergy
Undigested protein
Allergen
Allergen
Stimulate
Antibody
Cell
A. Opsonic phagocytosis
Combined opsonic activities
D. ADCC of NK
C. Effect of complement
Cell injury ways of type II hypersensitivity
Antigen or hapten on cell
Antibody (IgG, IgM)
Activate complement
Lyse target cell
Opsonic phagocytosis
Destroy target cell
Target cell injury
NK , phagocyte
Stimulate / block
ADCC
Change the function ofTarget cell
Mechanism of Type II hypersensitivity
Mechanism of type III hypersensitivity
 Formation of the intermediate immune complex
 Deposition of the intermediate immune complex
 Tissue injury by the immune complex
common disease of type III hypersensitivity
1. Local immune complex disease
Arthus reaction ：Experimental local reaction,
Necrotic vasculitis Ulcer
Human local reaction: insulin-dependent diabetes mellitus (IDDM)
2. Acute systemic immune complex disease
serum sickness
Anti-serum → Ab+Ag →
systemic tissue injury ,fever, arthritis, skin rash
Pinicillin、Sulfanilamide
Acute immune complex glomerulonephritis :
Streptococcus infection
3. Chronic immune complex disease:
SLE
Rheumatoid arthritis ：RF+IgG →
Deposit on synovial membrane
Type IV hypersensitivity
characteristics of type IV hepersensitivity
 mechanism of type IV hepersensitivity
common diseases of type IV hepersensitivity
Characteristics
Interaction of primed T cells and associated antigen
Infiltration of Mononuclear Cells, Inflammatory response
Mechanism of type IV hypersensitivity
 Formation of effector and memory T cells
 Inflammation and cytotoxicity caused by
effector T cells
1) Inflammation and tissue injury mediated by CD4+Th1
Release chemokines and cytokines
Immune injury mainly caused by infiltration of mononuclear
cells and lymphocytes
2) Cytotoxicity of CD8+
Common disease of type IV hypersensitivity
 Infectious delayed type hypersensitivity
OT( Old Tuberculin ) test
 Contact dermatitis
 Acute rejection of allogenic transplantation
Same disease (SLE), multiple immune injury ,hypersensitivity
involved
Same drug (penicillin), several types of hypersensitivity
 Sensitized T lymphocytes have secondary contact with
the antigen (hapten)
 conjugated with a protein and presented on the surface
of an antigen presenting cell (APC).
 APCs are the Langerhans’ cells
 Presentation of the antigen by :Langerhans’ cell to
CD4+ Th-1 type T lymphocyte
 Release of cytokines that produces T cell activation and
the recruitment of other non-antigen specific T cells and
macrophages to the site
inflammatory reaction : peak at 72 hours
clinically patch test reaction: localised area of
eczema
After 3–4 days, immunological mechanisms
downgrade the reaction and it gradually fades
away.
Standard series
All patients are patch tested to a standard of
allergens, such as the International, European,
North
American, or British Contact Dermatitis
Group (BCDG) standard series
British Contact Dermatitis Group
recommended standard series
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Neomycin sulfate
Thiuram mix 1
Paraphenylenediamine
Cobalt chloride
Formaldehyde
Rosin
Quinoline mix
Balsam of Peru
Isopropyl PPD
Wool alcohols
Mercapto mix
Epoxy resin
Paraben mix
PTBPF resin
Fragrance mix
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Quaternium
Nickel sulfate
Methylchloroisothiazolinone
Methylisothiazolinone
Mercaptobenzothiazole
Primin
Sesquiterpene lactone mix
Chlorocresol
Bronopol
Cetearyl alcoho
Fucidic aci
Tixocortol pivalate
Budesonide
Imidazolidinyl urea
Diazolidinyl urea
Methyldibromoglutaronitrile
Ethylenediamine dihydrochl
Contact dermatitis Allergens hazards in selected
occupations
Bakers:Flavouring, oil, antioxidant
Building trade workers:Cement (Cr, Co), rubber,resin,
wood
Caterers, cooks : fruit, veg,Veg/fruit, cutlery (Ni),rubber
glove
Cleaners: Rubber glove, nickel,
Dental personnel :
acrylate,
Rubber, acrylate
mercury
Electronics assemblers: Cr, Co, Ni
Patch Test: Materials
Finn chambers (shallow aluminium discs to hold
allergens) Hypoallergenic acrylate tape.
Allergens (diluted in various vehicles like
petrolatum, water, ethanol, acetone, olive oil,
etc.)
India Indian Standard Battery approved by CODFI
[Contact and Occupational Dermatoses Forum of
India] is usually employed Marker pen
Indications of Patch Test









Allergic Contact Dermatitis Syndrome (ACDS)
Atopic dermatitis
Nummular dermatitis (nummular eczema)
Seborrheic dermatitis presenting episodes of acute
inflammation)
Asteatotic eczema
Stasis dermatitis
Eczematous lesions around leg ulcer
Pompholyx and/or dyshidrotic eczema
Lichenification
Taking a history
 past and present occupation (possible contact with
industria allergenor irritants)
 Hobbies (plants,animals)
 cosmetics, and current and previous
treatments(potential medicamental hydrocortisone).
Selection of Patients
1. Taking less : 15 mg of oral steroid)
2. Not applying topical steroid on back for at least 1 week
3. Not having active or flared-up dermatitis
4. Not have been sunburned on back within last 2 weeks
5. Oral antihistamine can be continued during the process.
follow during the patch test procedure
Not to take bath or wash or wet the back
To avoid tight underclothes
To avoid exercise or activity causing sweating
To avoid friction/scratching
 avoid strong sun exposure.
Patch Test: Methods
 upper back (excluding vertebra and scapular angle)
 deltoid area (for small number of allergens)
 Site should be gently cleansed (with water and alcohol) and dried
 The top of patch test unit is marked and the protective foil removed
and they are kept with aluminium chambers faced up
 The protective foil is fixed longitudinally along the edge of the patch
test unit to facilitate handling
Reading the patch test reactions
 fixed on the upper back ; left on for two days.
 removed, marked, read with another reading at
four days
 problem in reading patch tests: differentiate
irritantreactions (which have no diagnostic value)
from allergic ones
Recording Patch test (la dou)
1 +=Weakreaction, nonvesicular,erythema,mild infiltration
2 + =Strongreaction, erythema, edema,vesicles
3 + =Extreme reaction, spreading ,bullous ,ulcerative
4 =Doubtful, faint erythema only
5 = Irritant reaction
6 =Negative
7 =Excited skin reaction
8 =Not tested
Recording patch test (0D)
+/− doubtful: faint erythema only
+ weak: erythema, maybe papules
++ strong: vesicles, infiltration
+++ extreme: bullous
Patch Testing
variety of substances found both in the industrial allergen
 Acrylates Adhesives
 Formaldehyde Preservatives
 Chromate Cement
 Detergents
 Cobalt Pigment
 Nickel Electroplating
 Epoxy resins
 jewellery manufacture
 Paints/resins
 Paraphenylenediamine
 Ethylenediamine
 Phenol formaldehyde
The possible side effects are explained
irritation on the back from the presence of the
patches,
 the production of an excessive reaction
worsening of the dermatitis in a number of cases,
and actually sensitised by the process of testing
 develop a “late” reaction—for example 1–3 weeks after( Gold
salts cause this)
 late reaction develops, often re-patch test after a suitable period
(for example, four weeks)
The management of contact dermatitis is
often difficult: overlapping factors
 testing helps identify the allergens involved
useful in dermatitis of the hands, face, feet
Most cases of occupational contact dermatitis:
mixed etiology
 Elimination of an allergen may not produce full
resolution →often irritant /endogenous factors at
play as well.
Difficult to eliminate fully all contact with
ubiquitous allergens such as nickel or colophony
Prick test
Diagnosis of allergic disease
most important
• History taking
• Physical examination
• Evaluation of causative allergen
 Skin test : prick, intradermal, patch
 Serum specific IgE :RAST
 specific allergen provocation test :nasal, bronchial, oral
Focus of Allergy diagnosis
 Is the patient atopic?
 Does allergy contribute to patient’s symptom?
 What are the clinical relevant allergens?
→allergen avoidance
→ environmental control
→immunotherapy, desensitization
Allergy History Taking
 Main dominant symptoms
 Associated symptoms
 Frequency and severity of symptoms, impact on
lifestyle
 Seasonal or perennial ?
 Triggering factors : allergic or non-allergic factor
 Occupation, hobbies
 Food, drug consumption history
 Possible allergen exposure in home
 Personal or family history of allergic disease
 Prior treatment response, side-effects
Skin test
• Purpose
 identification of causative allergens
 standardization of allergens : allergenic
potency
• Advantages
 easy to perform, fast
 not expensive
 high sensitivity
Skin test : method
• Prick test
• Intradermal test
• Scratch test
Skin prick test
 clean the test skin surface(back, forearm volar surface) with
cotton moistened with 75% alcohol and dry up
 place a small drop of each test extract and
positive/negative control solution 3-5cm apart
 prick with 25 or 26G needle and lift gently needle tip
upward
 read the wheal and flare reaction 15min later-read
Skin prick test : method
Skin prick test
Intradermal test
clean the test skin surface(back, forearm volar
surface) with 75% alcohol and dry up
intradermal injection of allergen extract with 1ml
syringe and 26G needle (approximately 2-4mm
diameter bleb, 0.02ml injection)
perform with positive/negative control solution
read the wheal and flare reaction 15min later
Controls
 false positive
-dermographism
-needle irritation
 false negative
-medication (e.g. antihistamine)
-underlying disease
-technical error
Factors affecting skin test
• Allergen extract
• Area of body
-back >> arm
-upper back >> lower back
-ulnar side of arm >> radial side of arm
• Age
-significant wheal detect in infants
-increase from infancy to adulthood
-decline after age of 50
• Sex, Race
• Seasonal variation
Drugs affecting skin test
• H1 antihistamine
• Imipramies, Phenothiazines: > 10days
• Systemic steroid
short-term(=1wk) : no effect
long-term : possible effect
• H2 blocker, leukotriene antagonist, theophylline, betaagonist: no clinical significance
Positive criteria
Size of wheal and erythema(flare)
prick test:
wheal size =3mm
flare=10mm
→ regarded as clinically significant allergy
intradermal test : wheal size =5mm
Interpretation
 Clinical relevancy
positive skin test ≠clinical allergic disease
consider asymptomatic sensitization, insignificant cross-reaction
(sensitization rate: 30-40% of general population)
Correlation with other allergy diagnostic test
 Diagnostic value of skin test:
• inhalant : most cheapest and effective method for respiratory allergy
• food : low sensitivity
• drug : variable, low sensitivity except penicillin