Asthma and AllergyAsthma and Allergy

Atopy v AllergyAtopy v Allergy

AsthmaAsthma

• Aeroallergens – indoor & outdoorAeroallergens – indoor & outdoor

Occupational allergensOccupational allergens

AtopyAtopy

The propensity to produce IgE to The propensity to produce IgE to allergensallergens

Demonstrated using Skin prick tests Demonstrated using Skin prick tests to common inhalant allergensto common inhalant allergens

Allergen-Antibody interactionAllergen-Antibody interaction

Prick Test ReagentsPrick Test Reagents

Skin Prick TestsSkin Prick Tests

AllergyAllergy

IgE mediated inflammatory tissue IgE mediated inflammatory tissue damage in response to an allergen damage in response to an allergen causing clinical diseasecausing clinical disease

Asthma - epidemiologyAsthma - epidemiology

X 2- 3 increase last 30 yearsX 2- 3 increase last 30 years

Concomitant similar increase in Concomitant similar increase in atopy, hayfever and eczemaatopy, hayfever and eczema

? Environmental Change? Environmental Change

? Less infections ( hygiene ? Less infections ( hygiene hypothesis )hypothesis )

AllergensAllergens

OutdoorOutdoor

Pollens-Pollens-– TreeTree– Grass Grass

Moulds- Moulds- – AlternariaAlternaria– AspergillusAspergillus– CladosporiumCladosporium– PenicilliumPenicillium

AllergensAllergens

IndoorIndoor– CatCat

– DogDog

– CockroachCockroach

– BirdsBirds

Inhalation of allergenInhalation of allergen Immediate response ( IgE mediated )Immediate response ( IgE mediated )

– Max: 20 min.Max: 20 min.– Ends : 60 min.Ends : 60 min.

Late response in 50% (Eosinophil )Late response in 50% (Eosinophil )– Onset 3hOnset 3h– Max 12 hMax 12 h– End 24 hEnd 24 h

Responsible for airways hyperreactivityResponsible for airways hyperreactivity

Allergen ID and avoidance therefore very importantAllergen ID and avoidance therefore very important

Pollenosis and BHRPollenosis and BHR

Allergic history and negative skin Allergic history and negative skin teststests

Remember grass pollen allergyRemember grass pollen allergy

PollenosisPollenosis Prof. Paul Potter, Cape TownProf. Paul Potter, Cape Town

Big role for grass pollens in respiratory allergyBig role for grass pollens in respiratory allergy

Kikuyu grassKikuyu grass

Bermuda grassBermuda grass

Buffalo grass ( l’herbe bourrique )Buffalo grass ( l’herbe bourrique )

SPT regents to detect allergy to these being developedSPT regents to detect allergy to these being developed

Mauritus has all of these grasses in abundanceMauritus has all of these grasses in abundance

Why study pollensWhy study pollens

Potential for immunotherapyPotential for immunotherapy

Indoor allergens-avoidanceIndoor allergens-avoidance

House dust mite allergenHouse dust mite allergen– LargeLarge

– Not easily air-borneNot easily air-borne

– Needs close proximity to bedding to be Needs close proximity to bedding to be inhaledinhaled

House dust mite avoidanceHouse dust mite avoidance

Mite impermeable mattress coversMite impermeable mattress covers

Hot wash bedding linen ( 55 C )Hot wash bedding linen ( 55 C )

Remove moquettesRemove moquettes

Light curtainsLight curtains

Vacuum clean with high filtration cleanerVacuum clean with high filtration cleaner

Mattress CoversMattress Covers

Vacuum cleanersVacuum cleaners

Pet allergensPet allergens

Remove the petRemove the pet

Clean itClean it

Remove carpets ( x 100 fold antigen)Remove carpets ( x 100 fold antigen)

Cat EvictionCat Eviction

Asthma- none of usual Asthma- none of usual aeroallergensaeroallergens

Think of occupational asthmaThink of occupational asthma

Occupational AsthmaOccupational Asthma

Asthma Asthma initiatedinitiated by an agent inhaled by an agent inhaled at workat work

Cf. Work-related asthmaCf. Work-related asthma– Pre-existingPre-existing asthma provoked by an asthma provoked by an

irritant in the workplaceirritant in the workplace

Occupational asthmaOccupational asthma

– Only a % of workers affectedOnly a % of workers affected

– Latent period before onset ( 2 Yr.)Latent period before onset ( 2 Yr.)

– Improvement during periods away from Improvement during periods away from workwork

– Once established can be triggered by Once established can be triggered by really small doses of antigenreally small doses of antigen

Usual suspectsUsual suspects HMWHMW ( Biologic ) ( Biologic )

– LatexLatex

– Flour ( 334 )Flour ( 334 )

– Laboratory mammals(188) Laboratory mammals(188)

– Bacillus subtilisBacillus subtilis

LMW LMW ( haptens )( haptens )– Colophony ( 175 )Colophony ( 175 )

– Wood dustWood dust

– Diisocyanates ( 658 )Diisocyanates ( 658 )

– Platinum saltsPlatinum salts

– Acid anhydrides ( 364 )Acid anhydrides ( 364 )

– GlutaraldehydeGlutaraldehyde

– Plastics workersPlastics workers

– Bone cementBone cement

Occupational AsthmaOccupational Asthma

Serial Peak Flow- latexSerial Peak Flow- latex

Bronchial Provocation TestingBronchial Provocation Testing

Inhalation ChallengeInhalation Challenge

Inhalation ChallengeInhalation Challenge

Occupational AsthmaOccupational Asthma

Occupational asthmaOccupational asthma

Diagnosis will have major impact on Diagnosis will have major impact on patient’s lifepatient’s life

False + ve : needless loss of jobFalse + ve : needless loss of job

False – ve : Needless continuing False – ve : Needless continuing exposureexposure

Be carefulBe careful

Thank YouThank You

DiscussionDiscussion