www.dgci.sote.huLecture ED 2015

Láng, Orsolya MD, PhDDept. Genetics, Cell & Immunobiology, Semmelweis University

Hypersensitivity

Hypersensitivity - Tolerance

Hypersensitivity:

Immune reaction leads to pathology upon recognition of either harmless environmental

antigens or self-antigens

Autoimmunity:

Autoreactivity is inevitable

Dysregulation or failure of self-tolerance => autoimmune disorder

Tolerance:

immunological unresponsiveness to (self)-antigens (tolerogen) that have

the capacity to elicit an immune response

Common:adaptive immune system

Hypersensitivity (HS) – Allergy The most common immunological abnormality. Increasing number of affected people (25-40%) Potential reasons: Environmental pollution (?)

Lack of selection (?)

General mechanism

Sensitization

Repeat exposure

Tissue injury ordisease

Robert Royston Amos ("Robin") Coombs: British immunologist, co-discoverer of the Coombs test (Arthur Mourant and Rob Race) in 1945

Gell - Coombs classification of hypersensitivity in 1963

First exposure

Four classifications

Type I (Immediate) hypersensitivity Type II (cytotoxic) hypersensitivity Type III (immune complex mediated) hypersensitivity Type IV (delayed) hypersensitivity

Types of hypersensitivities (Gell - Coombs classification)

Type Mediator Mechanism Time Disorders

I IgE mediated Mast cells and basophils

Histamine

Immediate1-2 mins

AllergyAnaphylaxy

(local and systemic)

II Cell or matrix associated antigens connecting IgG

4-6 hrs Transfusion reactionErythroblastosis

fetalisMyasthaenia gravis

Basedow disease

III Soluble antigen -IgG immunecomplex

Complement

2-8 hrs Arthus reactionRA, SLE

IV T cell mediatedT-cell response to antigens

Delayed2-3 days

Mantoux testChronic allergy

Contact dermatitis

Type I. hypersensitivity (HS)Immediate HS

or Allergy , Atopy

Atopy – inherited tendency to respond immunologically to inhaled or ingested allergens with increased IgE production

Hay fever

Bronchial asthma

Food allergies

Anaphylaxis

Common types of immediate HSInhaled allergens Ingestion

or injection

HivesUrticaria

Skin contact

Main characteristics of the allergenes

Small size proteins or glycoproteins:

- Carried on desiccated particles (pollen grains or mite feces), where they are very stable

- Have enzyme activity that facilitate the transmucosal penetrance- Small, molecular wheight is 5 to 70 kDa (dustmite: der p1 15 kD), - High solubility- Small dose (ragweed: 1µg/year)- MHCII binding

What do they have in common?

?

Hevein domain

Cross-reactive allergenes

http://ainotes.wikispaces.com/Pollen+Food+Allergy+Syndrome

Type I. hypersensitivity

First exposure

APC and Th2 activation

Class switch

IgE productionIgE+ memory B-cells

cross -linkedIgEMast cellsBasophils

FcᵋRI receptor

Repeat exposure

ACTIVATION and DEGRANULATION

Nature Review, Drug Discoverys alapján

IL4, IL13

IgE production Hypersensitivity

Degranulation

Afferent phase

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Class switch of BCR genes

INF

IL5

IL-4 IL-13

FcƐRI (high affinity)

FcƐRII (low affinity)FcƐRIIa on B cells

FcƐRIIb(CD23)

on mast cells and basophils

on B cells, T cells, Mφ-s, DC-s and basophils

Fc receptors

Kd= 10-11 M[IgE] = 10-9 M

MC are always coated with IgE bound receptors

15

Signaling induced by cross-linking of IgE

Effects of IgE cross-linking

(phospholipids)

17

Degranulation of MC

Other degranulators Immune

Anaphylatoxins: C5a, C3a Modulator

IL3 Non Immune

Bacterial products, gastrine, physical (cold), stress, chemical (gases, smoke), etc.

Intracellular signalling: Ca++

Inhibitors of degranulation Pharmacotherpy: cromoglicinum

Pro-inflammatory mediators released

by mast cells, basophils and

eosinophils

Gilfillan et al. Nature Reviews Immunology 6, 218-230 (March 2006) | doi:10.1038/nri1782

Primary mediators are in preformed granules

Physiological effect of mast cell degranulation

Histamine receptors

Histamine is the key mediator and their receptors

H1: e.g GIT, bronchoconstriction ↑; vessel permeabilty↑

H2: e.g. vasodilataion ↑; secretion of exocrine gland(e.g. gastric acid)↑; secretion

(H3: neural system)

H4: eosinophil chemotaxis

MC (Connective tissue) Mucosal MCsIntravenous ,

high doseSubcutanous,

low doseInhalation, low dose

Ingestion

Systemic anaphylaxis

urticaria Hay fever,

Bronchial asthma

Food allergy:

diarrhea, vomiting

utricaria, anaphylaxis

Role of the Mast cells (MC)

capillaries capillaries SM in brochus SM in intestin

Nature Medicine 18, 693–704 (2012) doi:10.1038/nm.2755

Immediate reaction in respiratory tract

Immediate and late phase symptoms

After 2 hrs After 1 day

PEFR = peak expiratory flow rate

Chronic inflammation and complications (tissue remodelling)

Nature Medicine 18, 693–704 (2012) doi:10.1038/nm.2755

Atopy

Atopy is the term for the genetic trait to have a predisposition for localized anaphylaxis.

Atopic individuals have higher levels of IgE and eosinophils.

Allergy – Multifactorial disorder

Allergy

GeneticsFcƐRI beta chain - 11q13

IL-3, IL-4, IL5, IL-9, IL-13 and GMCSF coding genes - 5q31MHCII allels - 6p

Environmental factorsFailure of tolerance during

childhood

Dysregulaion of the Immune system

Activation of Th1 and Th2 subpopulationIgE production

ImmunodeficiencyIncreased eosinophil count

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DER p1 in the faeces of the house dust mite penetrates the airway epithelium

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Bronchial asthma

normal bronchiole severe asthma

• Anaphylactic shock is the most serious

• Symptoms are directly related to the massive release of vasoactive substances leading to fall in blood pressure, shock, difficulty in breathing and even death.

• It can be due to the following:– Horse gamma globulin given to patients who are sensitized to

horse protein.– Injection of a drug that is capable of acting as a hapten into a

patient who is sensitive, ie, penicillin.– Following a wasp or bee sting in highly sensitive individuals.– Foods – peanuts, shellfish, etc.

Anaphylaxis

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Staphylococcus exotoxins may serve either as superantigens or allergens

!

Non specific T-cell activation

– Avoidance of known allergens

– Localized reactions use OTC antihistamines and decongestants.

– Asthma uses combination – antihistamines, bronchodilators and corticosteroids.

– Systemic use epinephrine

– Hyposensitization – inject antigen to cause production of IgG which binds to antigen (allergen) before it reaches IgE coated cells.

– Monocolonal anti-IgE – inject, binds to receptors on mast cells blocking them from the IgE.

Therapy

Administration of increasing doses of antigen

desensitization

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DESENSITIZATION – Allergen-specific immunotherapy

http://www.fpnotebook.com

http://www.voedselallergie.nl/allergic-and-non-allergic-hypersensitivity-to-food

Repeated administration of the sensitizing allergen usually by subcutaneous injection or, more recently, by sublingual application.

Both IgE- and IgG-specific antibodies increase during postdesensitization therapy.

IgG acts as blocking Ab

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Anti-IgE therapy

Nature Reviews Immunology 8, 218-230 (March 2008)

Monoclonal antibody

In vivo test - Intradermal allergy test (Prick test)

Small amount of allergen injected into skin Look for wheal formation of 3mm or greater in diameter Simple, inexpensive, can screen for multiple allergens. Stop anti-histamines 24-72 hours before test. Danger of systemic reaction Not for children under 3

In vitro test

Protein arrayRAST RadioAllergoSorbent Test

Measure total IgE or antigen-specific IgE in serum Less sensitive than skin tests.R IST, RAST, Allergen specific and Microarray will be covered later.

Anaphylaxis vs. Anaphylactoid reaction (pseudoallergy)

Anaphylaxy/ allergy Anaphylactoid reaction/ pseudoallergy

IgE mediated allergic reaction in sentizized patient

triggering material is capable of direct mast cell or basophil degranulation to induce, and thus cause histamine release

•Foods (particularly nuts and seafood) •Drugs (particularly beta-lactam antibiotics) •Insect stings/bites (bees, wasps and fire ants) •Latex •….

•Drugs (particularly NSAIDs, aspirin, opioids) •Radiographic contrast media (CT/MR)•High histamine containing food (red wine), bacterial toxins generated from histidine (scombroid fish - fish that were inadequately refrigerated or preserved after being caught)

Ibuprofen v.COX1 inhibitor

No test!

4 type of pseudoallergy based on COX1 inhibition

http://allergycases.blogspot.hu/2010/07/allergic-and-pseudoallergic-reactions.html

Type II. hypersensitivity (HS)

Type II. hypersensitivity

Cell surface antigen (IgG v. IgM)

Antigens:Intrinsic - autoantigen, Membrane component(receptor)

Extrinsic antigenRBC – tarnsfusion, Rh incompatibilityAbsorbed drugs or metabolits

Opsonization => phagocytozisFc-receptor mediated phagocytosis/ cell lysis (macrophage, NK cell, neutrophil & eozinophil)

Complement activation=> cell lysis

ADCC (antibody dependent cellular cytotoxicity)

Abnormal physiologic response:

Ab inhibits binding of neurotransmitteranti Ach R: myasthenia gravis

Ab stimulate receptoranti-TSH R: autoimmune thyroiditis

Pathomechanisms of type II. hypersensitivity

Hemolysis

Transfusion reactionIncompatible transfusion - IgM

Polytransfused - IgGMultipara - IgG

Not only RBC, but Platelets or leukocytes

Complication:Erythroblastosis fetalis

Rh incompatibility

Haemolytical disease of the newborn

Erythroblastosis fetalis

Erythroblastosis fetalis

Passive immunizationwith anti-Rh

Haemolytic anaemia and thrombocytopeny

Drugs/ metabolits can act as a hapten – e.g. penicillin

Drug allergy (penicillin)

Myastenia Gravis

3 hrs after methyl prednisolon treatment

ptosis

Altering signal transduction

- Autoimmune thyroiditisGraves- Basedow

exophtalmus

+

Type III. HS

Soluble antigen-antibody complex - IMMUNE COMPLEX disease

Pathomechanism

Solubile Ag - Ab (IgG or IgM) => IC =>Complement activation=> inflammation and tissue injury

Mechanism of the tissue destruction similar in all tissueSeverity depends upon: size of the IC,

ratio of Ag/Ab, affinity of Ab, isotype of Ab

The consequence of the tissue damage depends on the site of deposition

1. Local immune complex diseaseArthus reaction – skin

necrotic vasculitis – vascular wall pneumonitis – farmer’s lung

2. Acute-systemic immune complex disease acute serum disease (7-10 days) 3. Chronic immune complex disease SLE Rheumatoid arthritis

Pathomechanism – Arthus reaction

Ag exposureor vaccination

Ag –Ab complexComplement

activation

Mast cell degranulationFcgammaRIII

Inflammation

4-12 hrs severe pain, swelling, induration, edema, hemorrhage, and occasionally by necrosis

Key mediators: C3a C5a

Arthus reaction(experimental):

- local response induced by intradermal injection of the Ag in sentitized patient

Vasculitis Farmer’s lung

Actinomyces:Saccharapolyspora rectivirgula

Type IV. HST cell mediated disease

Delayed HS

Ags inducing type IV. HS

Contact Ag Nickel salts, chromate

Poision ivry, oak

picricchlorine

Hair stain

IC bacteria Mycobacterium tuberculosis, leprae

Lysteria monocytogenes

Brucella abortus

Fungi Candida albicans

Pneumocystis carinii

Cryptococcus neoformans

histoplasmosis

Viruses Herpes simplex

Small pox

Measles

DTH – delayed Type HypressensitivityIt takes aprx 12 hrs as Th1 cells are involved

Type IV. HS

Syndrome Antigen Symptomes

Late type hypersensitivity ProteinsInsect proteinMycobacterial protein(tuberculin, lepromin)

Local skin swelling:ErythemaInduration (hardening)Cellular infiltrationDermatitis

Contact hypersensitivity Haptens Pentadeca-chatechol (poison

ivy) Paraphenylene diamine (hair

stain) Metallic ions: Nickel,

Chromium

Local skin reaction:ErythemaCellular infiltrationBlistersIntra-epidermal foci

Gluten sensitive enteropathyCeliac disease – flour

sensitivity

Gliadin (grain protein) Atrophy of microvilli in the small intestine

UndernutritionDamaged exocrine secretion of

pancreas

Th17Neutrophil

recruitment

Langerhans scells uptake the Ag

Ag presentation to TH1 cells

Activation of the keratinocytes

Macrophage activation

inflammation

Contact reaction

TNF-alpha, betaTissue

destruction

INFgammaMacrophage

activation

Tetsuya Honda(2013) 133, 303-315. doi:10.1038/jid.2012.284

A schematic view of the sensitization phase

Activation of the innate immune system by contact allergens (haptens, Ni2+)

Upon reexposure to haptens

Tuberculin Hypersensitivity Mantoux test (it detects infection)

• Maximum at 48-72 hours• Inflitration of lesion with mononuclear cells• Responsible for lesions associated with bacterial allergy

– cavitation, caseation, general toxemia seen in TB

• May progress to granulomatous reaction in unresolved infection

Granuloma Formation

Diagnostic test: Patch test – Epicutan testAllergen containig adhesive tape is fixed to the back,

evaluation after 48, 96 hrs and later (4.-6. days).

Steroids, antihistamins may influence the test result

Diagnosis based on the reaction

Latex allergy

Type I. HS

Latex-allergen

UrticariaAnafilaxy

Type IV. HS

Chemicals

DTHDermatitis

Not immunological

Chemicals, soapa

Irritative contact dermatitis

It is important to distinguishi: side effect Toxicity Intolerance Idiosyncrasy immun mediated reaction - hypersensitivity

Penicillin

Penicillin-RBC

IgM, IgG

Hemolytic anaemia

Type II. drug induced anaemia

Complement

Penicillin

Penicillin-protein

IgG

IgG immuncomplex

Serum sicknessglomerulonephritis

Type III. HS

Penicillin-protein

IgE

IgE-Mast cell

Penicillin

Systemic anaphylaxis

urticaria

Type I. Drug allergy

target

Penicillin

Penicillin-protein

TDTH

Macrophage activation

Contact dermatitis

Type IV. HS

targettargettarget

Penicillin allergy

Allegies in dentristry

Chlorhexidine: including allergy (Type I HS ) and allergic contact dermatitis/stomatitis (Type IV HS)

Metals- e.g. Ti : Type I and VI. HS stomatitis, facial erythema

Flouride - Type I and VI. HS skin rashes, mouth lesions

MELISA test (Memory Lymphocyte Immunostimulation Assay )

clinically useful in identifying metal hypersensitivities

1.Blood sample2.Lymphocytes are isolated and then incubated for 5days with individual metals. 3. in HS patient if T cells re-encounter that metal in the culture, they proliferate, 4. Assessment is based measurement of T cell proliferation has occurred in response to that metal.