Asthma and Allergy  Atopy v Allergy  Asthma Aeroallergens – indoor & outdoor Aeroallergens – indoor & outdoor  Occupational allergens

Atopy  The propensity to produce IgE to allergens  Demonstrated using Skin prick tests to common inhalant allergens

Allergen-Antibody interaction

Prick Test Reagents

Skin Prick Tests

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

Asthma - epidemiology  X 2- 3 increase last 30 years  Concomitant similar increase in atopy, hayfever and eczema  ? Environmental Change  ? Less infections ( hygiene hypothesis )

Allergens  Outdoor  Pollens- –Tree –Grass  Moulds- –Alternaria –Aspergillus –Cladosporium –Penicillium

Allergens  Indoor –Cat –Dog –Cockroach –Birds

Inhalation of allergen  Immediate response ( IgE mediated ) –Max: 20 min. –Ends : 60 min.  Late response in 50% (Eosinophil ) –Onset 3h –Max 12 h –End 24 h  Responsible for airways hyperreactivity  Allergen ID and avoidance therefore very important

Pollenosis and BHR

Allergic history and negative skin tests  Remember grass pollen allergy

Pollenosis  Prof. Paul Potter, Cape Town  Big role for grass pollens in respiratory allergy  Kikuyu grass  Bermuda grass  Buffalo grass ( l’herbe bourrique )  SPT regents to detect allergy to these being developed  Mauritus has all of these grasses in abundance

Why study pollens  Potential for immunotherapy

Indoor allergens-avoidance  House dust mite allergen –Large –Not easily air-borne –Needs close proximity to bedding to be inhaled

House dust mite avoidance  Mite impermeable mattress covers  Hot wash bedding linen ( 55 C )  Remove moquettes  Light curtains  Vacuum clean with high filtration cleaner

Mattress Covers

Vacuum cleaners

Pet allergens  Remove the pet  Clean it  Remove carpets ( x 100 fold antigen)

Cat Eviction

Asthma- none of usual aeroallergens Think of occupational asthma

Occupational Asthma  Asthma initiated by an agent inhaled at work  Cf. Work-related asthma – Pre-existing asthma provoked by an irritant in the workplace

Occupational asthma – Only a % of workers affected – Latent period before onset ( 2 Yr.) –Improvement during periods away from work –Once established can be triggered by really small doses of antigen

Usual suspects  HMW ( Biologic ) –Latex –Flour ( 334 ) –Laboratory mammals(188) –Bacillus subtilis  LMW ( haptens ) –Colophony ( 175 ) –Wood dust –Diisocyanates ( 658 ) –Platinum salts –Acid anhydrides ( 364 ) –Glutaraldehyde –Plastics workers –Bone cement

Occupational Asthma

Serial Peak Flow- latex

Bronchial Provocation Testing

Inhalation Challenge

Occupational Asthma

Occupational asthma  Diagnosis will have major impact on patient’s life  False + ve : needless loss of job  False – ve : Needless continuing exposure  Be careful

Thank You  Discussion