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Allergens in Asthma Asthma and Allergy eczema

VIEWS: 9 PAGES: 33

									          Asthma and Allergy
 Atopy   v Allergy

 Asthma


•   Aeroallergens – indoor & outdoor


 Occupational   allergens
                 Atopy
 The propensity to produce IgE to
 allergens

 Demonstratedusing Skin prick tests
 to common inhalant allergens
Allergen-Antibody interaction
Prick Test Reagents
Skin Prick Tests
              Allergy


 IgEmediated 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 )               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



      – ve
 False          : Needless continuing
 exposure

 Be   careful
Thank You



Discussion

								
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