HYPERSENSITIVITY
&
AUTOIMMUNITY
Angol Denish Calmax
OUTLINE

Overview

Type I hypersensitivity
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Type II hypersensitivity

Type III hypersensitivity

Type IV hypersensitivity

Autoimmunity
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References
OVERVIEW
TYPE I HYPERSENSITIVITY
(Immediate Hypersensitivity)....1
HYPERSENSITIVITY
The term hypersensitivity is used to describe immune responses
which are damaging rather than helpful to the host.
HISTORY
Nearly 45 years ago Gell and Coombs proposed a
classification scheme which defined 4 types of hypersensitivity
reactions.
TYPES OF HYPERSENSITIVITY
The four types of hypersensitivity are:
1. Type I Hypersensitivity- IgE mediated
2. Type II Hypersensitivity- Antibody mediated
3. Type III Hypersensitivity- immune complex
4. Type IV Hypersensitivity- cell mediated
The first three are mediated by antibody, the fourth by T cells.
TYPE I HYPERSENSITIVITY
(Immediate Hypersensitivity)....2
Testing for Immediate Hypersensitivity...1
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In Vivo Skin Tests (Cutaneous or intradermal)
-Cutaneous testing or a prick test: a small drop of material is injected into the skin at a single
point. After 15 minutes, a WHEAL (raised & reddened part of skin) 3 mm greater in diameter
than the negative control (saline) is POSITIVE
- Intradermal test: A 1 mL tuberculin syringe is used to administer 0.01 to 0.05 mL of test
solution between layers of the skin. After 15-20 mins, a WHEAL 3 mm greater in diameter
than the negative control (saline) is POSITIVE
In Vitro Tests:
RIST- radioimmunosorbent test
- Total IgE
-competitive & non-competitive
RAST- radioallergosorbent test
- Antigen-Specific IgE Testing
-non-competitive
Microarray Testing
Testing for Immediate
Hypersensitivity...2
TYPE II HYPERSENSITIVITY
(cytotoxic hypersensitivity)
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The reactants (antibodies) responsible for type II
Hypersensitivity are IgG and IgM
Triggered by antigens found on cell surfaces (altered selfantigens or heteroantigens)
Promoting phagocytosis by both opsonization and activation of
the complement cascade
Examples: Transfusion Reactions, Hemolytic disease of the
newborn (HDN), Autoimmune Hemolytic Anemia (Warm
autoimmune hemolytic anemia or Cold autoagglutinins )
and Type II Reactions Involving Tissue Antigens(e.g.
Goodpasture’s syndrome)
Testing for Type II Hypersensitivity
Coombs’ test
 Direct Coombs’ test (Direct antiglobulin testing, DAT)
detects:
- transfusion reactions
-haemolytic disease of the newborn (HDN)
-autoimmune haemolytic anaemia
 The indirect Coombs’ test is used in the cross-matching of
blood to prevent a transfusion reaction.
TYPE III HYPERSENSITIVITY


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Involves soluble antigen but also IgG or IgM and
complement mediation.
The soluble antigen combines with antibody,
complexes are formed that precipitate out of the
serum & deposit in the tissues if the immune system is
overwhelmed
Examples: Arthus Reaction, Serum Sickness
Testing for Type III Hypersensitivity


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Detection of antibody by:
-agglutination reactions using antigen-coated carrier
particles e.g. red blood cells or latex particles
-enzyme immunoassays
Fluorescent staining of tissue sections to determine
deposition of immune complexes in the tissues
More general method of determining immune complex
diseases is by measuring complement levels (decreased
level shows antigen–antibody combination )
TYPE IV HYPERSENSITIVITY
(Delayed hypersensitivity)
Langerhans cells in the skin and macrophages in the tissue capture and present
antigen to Th 1 cells.
 The Th1 cells are activated and release cytokines (e.g. IL-3, IFN-γ, TNF-β and TNF-α)
that recruit macrophages and neutrophils, produce edema, promote fibrin deposition,
and generally enhance an inflammatory response

Cytotoxic T cells are also recruited, and they bind with antigen-coated target cells
to cause tissue destruction
 Initial sensitization phase is1 to 2 weeks after the first contact with antigen
 Upon subsequent exposure to the antigen, symptoms typically take several hours to
develop and reach a peak 48 to 72 hours
NB: The rxn can only be transferred to other animals through transfer of T lymphocytes.

Examples: Contact Dermatitis, Hypersensitivity Pneumonitis, Tuberculin-Type
Hypersensitivity

Testing for Delayed Hypersensitivity...1

The patch test (gold standard)
-Be done when the patient is free of symptoms or when
he or she at least has a clear test site.
-A non-absorbent adhesive patch containing the
suspected allergen is applied on the patient’s back,
and the skin is checked for a reaction over the next 48
hours.
-Redness with papules or tiny blisters is considered a
POSITIVE test.
-Final evaluation is conducted at 96 to 120 hours.
Testing for Delayed Hypersensitivity
(The patch test-gold standard)....2
ILLUSTRATION
STRONG POSITIVE RESULT
Testing for Delayed
Hypersensitivity...3

Mantoux method skin test
-Typically, 0.1 mL of the antigen is injected
intradermally, using a syringe and a fine needle
-The test site is read at 48 and 72 hours for the
presence of induration (hardening).
-An induration of 5 mm or more is considered a
POSITIVE test.
-Examples of antigen used: Candida albicans, tetanus
toxoid, tuberculin, and fungal antigens (e.g. trichophyton
and histoplasmin)
Testing for Delayed Hypersensitivity
(Mantoux method skin test)...4
The intradermal
injection
The measurement
SUMMARY
characteristics
TYPE-I
(anaphylactic)
TYPE-II
(cytotoxic)
TYPE-III
(immune
complex)
TYPE-IV
(delayed type)
Antibody
IgE
IgG, IgM
IgG, IgM
None
Antigen
exogenous
cell surface
soluble
tissues & organs
Response time
15-30 minutes
minutes-hours
3-8 hours
48-72 hours
Appearance
weal & flare
lysis and
necrosis
erythema and
edema, necrosis
erythema and
induration
Histology
basophils and
eosinophil
antibody and
complement
complement and
neutrophils
monocytes and
lymphocytes
Transferred
with
antibody
antibody
antibody
T-cells
Examples
allergic asthma,
hay fever
Erythroblastosis
fetalis,
Farmer's lung
disease
tuberculin test,
poison ivy,
granuloma
AUTOIMMUNITY



Autoimmune diseases are conditions in which organs or
tissues are damaged as a results of the presence of
autoantibody or autoreactive cells
Affect 5-7% of the population and are thought to be
caused by the loss or breakdown of self-tolerance
Examples: Systemic Lupus Erythematosus, Rheumatoid
Arthritis, Autoimmune Thyroid Diseases, Type I
Diabetes Mellitus, Other diseases (Multiple Sclerosis,
Myasthenia Gravis, Goodpasture’s Syndrome)
EXAMPLES OF AUTOIMMUNE DISEASES
Systemic Lupus Erythematosus
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Chronic, systemic inflammatory disease caused by immune
complex formation.
The word "systemic" means the disease can affect many
parts of the body.
Pathophysiology associated with clinical features
secondary to immune complexes depositing in tissues
resulting in inflammation.
Parts of the body affected include: the joints, skin,
kidneys, heart, lungs, blood vessels, and brain.
Laboratory Diagnosis of Systemic Lupus
Erythematosus (SLE)...2
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
Screening test for anti-nuclear antibodies (ANA) first
test done.
-Antibodies directed against nuclear material of cells.
Flourescent anti-nuclear antibody (FANA) most
widely used, extremely sensitive, low diagnostic
specificity.
 Animal or human cells fixed to slide.
 Add patient serum and incubate.
 Wash to remove unreacted antibody.
 Add anti-human globulin labeled with
fluorescent tag or enzyme.
Laboratory Diagnosis of Systemic Lupus
Erythematosus (SLE)...3
Anti-nuclear antibodies (ANA) test

Patterns of reactivity:
Homogenous-entire nucleus
stained
Peripheral-rim of nucleus stained
Speckled-spots of stain throughout
nucleus
Nucleolar-nucleolus only stained

False positives and negatives
occur.
Extractable Nuclear Antigen (ENA) for
SLE
Rheumatoid Arthritis
Laboratory Diagnosis of
Rheumatoid Arthritis
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Laboratory tests involve testing patients serum with red
blood cells or latex particles coated with IgG,
agglutination is a positive result.
Nephelometry and ELISA techniques are available to
quantitate the RF
Erythrocyte Sedimentation Rate (ESR) used to monitor
inflammation
C-Reactive protein (CRP) is utilized to monitor
inflammation
Laboratory Testing of type I Diabetes
Mellitus

Recommendations for diagnosing diabetes state is that,
patients be told they have diabetes if any of the criteria
below applies:
Fasting plasma glucose is above 126 mg/dl;
Diabetes symptoms exist and casual plasma glucose is equal to
or above 200 mg/dl; or
Plasma glucose is equal to or above 200 mg/dl during an oral
glucose tolerance test.
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If genetic predisposition is suspected perform testing to
detect antibodies to pancreatic islet cells.
Antibodies to insulin detected by RIA or ELISA methods.
Multiple Sclerosis, MS
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Because the myelin is damaged, messages moving
along the nerve are transmitted more slowly or not at
all which slows or blocks muscle coordination, visual
sensation and other nerve signals.
Diagnosis of MS

The basic guideline for diagnosing MS relies on two
criteria:
There must have been two attacks at least one month apart. An
attack, also known as an exacerbation, flare, or relapse, is a
sudden appearance of or worsening of an MS symptom or
symptoms which lasts at least 24 hours.
There must be more than one area of damage to central
nervous system myelin—the sheath that surrounds and protects
nerve fibers. The damage to myelin must have occurred at
more than one point in time and not have been caused by any
other disease that can cause demyelination or similar
neurologic symptoms.
Laboratory Diagnosis of MS
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
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Cerebrospinal fluid (CSF) is tested for levels of certain
immune system proteins and for the presence of oligoclonal
bands.
These bands indicate an abnormal autoimmune response
within the central nervous system, meaning the body is
producing an immune response against itself.
Oligoclonal bands are found in the spinal fluid of about
90-95% of people with MS, but since they are present in
other diseases as well, they cannot be relied on as positive
proof of MS. They may also take some years to develop.
CSF Analysis for MS
Myasthenia Gravis
Laboratory Testing of Myasthenia
Gravis
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
Autoantibodies to the Acetylcholine receptor
(AChRAb) can be detected in 80-90% of patients
with myasthenia gravis.
The assay measures antibodies that precipitate
solublized muscle AChR that has been complexed
with radiolabeled alpha- bungarotoxin (αBTX).
Antibodies that bind to the receptor regions that are
not sterically blocked by the αBTX are detected.
Goodpasture’s Syndrome
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Antibodies react with antigens in the glomerular
basement membrane of the kidney, results in
severe necrosis.
Antigen in kidney is similar to antigen found in
lungs, resulting in antibody reacting with lung
tissue resulting in pulmonary hemorrhage.
Specific anti-basement antibodies can be
demonstrated.
Diagnosis
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Lung needle biopsy and a kidney biopsy will show immune
system deposits.
Kidney biopsy can also show the presence of the harmful
antibodies that attack the lungs and kidneys
Antiglomerular basement membrane (anti-GBM) antibody
Enzyme immunoassay (EIA)
Antibodies to Neutrophil Cytoplasmic Antigens (ANCA)
identified by immunofluorescence
Autoimmune Thyroid Diseases
(Hashimoto’s Thyroiditis & Graves’ Disease)
Hashimoto's Thyroiditis
 Hashimoto's Thyroiditis is a type of autoimmune thyroid
disease in which the immune system attacks and destroys
the thyroid gland.
 The thyroid helps set the rate of metabolism - the rate at
which the body uses energy.
 Hashimoto’s prevents the gland from producing enough
thyroid hormones for the body to work correctly.
 It is the most common form of Hypothyroidism
(underactive thyroid).
Laboratory Testing of Autoimmune
Thyroid Diseases
(Hashimoto’s Thyroiditis & Graves’ Disease) .....1
Laboratory Testing Hashimoto’s Thyroiditis (goitre)- hypothyroidism.
 The diagnosis of Hashimoto's thyroiditis is simply diagnosed by two blood
tests.
 Routine thyroid function tests to confirm that a patient has an
underactive thyroid gland.
 Anti-microsomal and anti-thyroglobulin antibodies are Igs which the
body produces to attack specific portions of the thyroid cells which
pinpoint Hashimoto's thyroiditis as the cause of the hypothyroidism.
 The anti-microsomal antibody test is much more sensitive than the antithyroglobulin, therefore some doctors use only the former blood test.
 These thyroid autoantibodies blood tests are high in about 95% of patients
with Hashimoto's thyroiditis, but are not diagnostic.
Laboratory Testing of Autoimmune
Thyroid Diseases
(Hashimoto’s Thyroiditis & Graves’ Disease) .....2
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Laboratory testing of Graves’ Disease –
Thyrotoxicosis
Diagnosis may be straightforward, since the
"classic face" with its triad of
hyperthyroidism, goiter, and exophthalmos
is easily recognized.
Detection of the thyroid hormones T3 & T4,TSH
using RIA
Exophthalmos

Exophthalmos, also called proptosis, is a
characteristic finding in thyroid eye disease, and
has been reported to occur in 34% to 93% of
patients
References
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Christine Dorresteyn Stevens, (2010). Clinical Immunology Serology A
LABORATORY PERSPECTIVE 3rd Edition F.A. Davis Company1915 Arch
Street Philadelphia, PA 19103 pgs 201-238 www.fadavis.com
http://www.ucl.ac.uk/~regfjxe/Arthritis.htm
http://www.haps.nsw.gov.au/edrsrch/edinfo/lupus.html
http://pathmicro.med.sc.edu/ghaffar/tolerance2000.htm
http://repro-med.net/info/cat4.php
http://stemcells.nih.gov/info/scireport/chapter6.asp
http://www-ermm.cbcu.cam.ac.uk/04008427h.htm
http://www.biotest.de/ww/en/pub/folder_pharma/fields_of_use/autoimm
une_disease.htm
http://72.14.203.104/search?q=cache:H7KcpVQ4xkYJ:www.peppypaws.c
om/Glossary.html+Forbidden+clone+theory&hl=en&client=firefox-a
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