Asthma and Allergy
 Atopy
v Allergy
 Asthma
•
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
 Clean
the pet
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 )

LMW ( haptens )
– Latex
– Colophony ( 175 )
– Flour ( 334 )
– Wood dust
– Laboratory mammals(188)
– Diisocyanates ( 658 )
– Bacillus subtilis
– Platinum salts
– Acid anhydrides ( 364 )
– Glutaraldehyde
– Plastics workers
– Bone cement
Occupational Asthma
Serial Peak Flow- latex
Bronchial Provocation Testing
Inhalation Challenge
Inhalation Challenge
Occupational Asthma
Occupational asthma
 Diagnosis
will have major impact on
patient’s life
 False + ve : needless loss of job
 False
– ve
exposure
 Be
careful
: Needless continuing
Thank You
Discussion