1. Diagnosis of Occupational Allergy
Andreas Lopata
University of Cape Town
Division of Immunology
Allergology Section

2. Figure 12-2

3. Adverse Reactions to Allergens

4. Induction and effector mechanisms in IgE-mediated hypersensitivity
Allergen
Processing &
Presentation
Activation
IgE
Mediators
Pharmacological
blood vessels,
airways, etc.,
Clinical Effects
asthma,
eczema,
hay fever
clinical
effects
media
release
mast cell
activation
production
antigen
presentation
Exposure

6. Figure 12-7

7. Clinical manifestations of Occupational Allergy
Domestic
Occupational
Ingestion Skin contact Inhalation
GIT
Cutaneous
Respiratory
Abdominal pain Nausea Diarrhoea
Flushing Urticaria Protein Contact Dermatitis (PCD)
Asthma Rhinitis Conjunctivitis
Generalised Reaction
Anaphylaxis

8. Figure 12-1

9. 5 Stage Investigation 1. Detailed history and physical examination
2. Evaluation of the patient’s environment
3. Confirmation of the presence of atopy
4. Identification of specific allergen sensitivity
5. Monitoring the ongoing inflammation

10. Analytes measured in the Diagnostic Allergy Laboratory
Exposure
Allergen-specific IgG (Hymenoptera; Birds)
Identification of allergen exposure in food
Indoor aeroallergen quantification
Der p 1/Der f 1
Fel d 1/Can f 1
Bla g 1/ Bla g 2
Mus m 1
Aeroallergen quantification in the work-place
α-Amylase, Wheat, Rye
T. urticae (Red Spider mite)
Storage mite
Parvalbumin, Tropomyosin
Latex
Cotinine (marker for smoking)

12. Food Allergen Facts
Allergenic foods contain over 10,000 different proteins
Only few cause allergic reactions; about 60 sequenced
Physicochemical properties
Abundance
Molecular weights kDa
Acidic isoelectric point
Glycosilated
Resistance to heat and digestion (exceptions fruits !)

13. Secondary Structure of some Food Allergens
Rapseed
Barley
Wheat
Soybean
Breiteneder and Radauer (2004), J Allergy Clin Immunol

14. Conformational Changes during Processing
Protein
Sampson (2004) J. Allergy Clin. Immunol.

15. “Diagnosis” of the Environment
- Which Allergens -
Allergens in the Food Processing Industry
Animal Products
Fish/Crustacean/Molluscs
Poultry/Milk/Cows/Eggs
Insects-Mites/weevils/roaches
Plant Products
Latex
Grains
Flours-Wheat/Rye
Enzymes-Fungal amylase
Spices
Others- Woods/Pigeons/Mushrooms/Pollen

16. Classification of Seafood Groups
Phylum
Class
Common Name
Mollusca
Gastropoda
Abalone, snail
Bivalvia
Clams, oyster, mussel
Cephalopoda
Squid (cuttlefish), octopus
Arthropoda
Crustacea
Crab, rock lobster, prawn, shrimp
Chordata
Osteichtyes (bony fish)
Salmon, hake, tuna, herring, sardine (pilchard), mackerel

17. Pilchard antigen [ng / m3]
Quantification of fish antigens
In a fish processing factory
600
500
400
Pilchard antigen [ng / m3]
300
200
100
Control
Control
Autopacker
Exhaust box
Sorting table
Control
Bagging
Packaging
Fish canning
Fishmeal processing
Lobster processing

18. Anchovy antigen [ng / m3]
Control
Sorting table
Exhaust box
Autopacker
Bagging
Packaging
Fish canning
Fishmeal processing
Lobster processing
500
1000
1500
2000
2500
3000
Anchovy antigen [ng / m3]

19. Work processes associated with high-risk exposure to Seafood
Rock-lobster processing (water-jet scrubbing).
Fish canning (gutting and heading)
Fish-meal processing (bagging)

20. Investigating Allergy
History
Skin Prick Test (SPT)
Bronchial challenge
In-vivo
Radioallergosorbent test (RAST)
EAST
Immunoblot
Cellular stimulation; CAST-assay
In-vitro

21. Induction and effector mechanisms in IgE-mediated hypersensitivity
Allergen
Processing &
Presentation
Activation
IgE
Mediators
Pharmacological
blood vessels,
airways, etc.,
Clinical Effects
asthma,
eczema,
hay fever
clinical
effects
media
release
mast cell
activation
production
antigen
presentation
SPT
CAST
BLOT
RAST

22. Analytes measured in the Diagnostic allergy laboratory
Diagnosis
Allergen-specific IgE
Multiallergen-specific IgE screen
Individual allergen specificities
Total Serum IgE
Precipitating antibodies specific for proteins in organic dust
Tryptase (marker for mast cell mediated anaphylaxis)
Mediators:
Preformed amine: Histamine
Newly formed: Leukotriens (LTC4) and prostaglandins (PGD2)
Other markers: Proteases, Cytokines, Eosinophilic cationic protein
Other tests: complete blood cell count, eosinophils in sputum

23. Detection of specific IgE antibodies Separation of proteins
- Heat stability of different Crustacean Proteins -

24. Heat stability of different Crustacean Allergens

25. Detection of specific IgE antibodies
Immunoblot to South African crustacean species A B 1 2 3
kDa 75 35 25
1. Cape Rock Lobster (“Crayfish”)
2. Prawn
3. Langoustine
(Lopata et al. (2001), ACI International

26. Immunoblot of worker exposed to LocustsMA JJ
Contr. A
1. Locust Wings/Legs 2. Locust Gut 3. Locust Faeces MW 1 2 3
kDa _ 97 46 30 14
Lopata et al. 2005, Allergy 1

27. In-Vitro detection of IgE antibodies Pharmacia CAP® System
Pharmacia CAP® System is based on this tiny ImmunoCAP, a further
development of RAST® (improved binding of more allergens/Ab)

28. Pharmacia CAP® System “ UniCAP “

29. Spectrum of Allergy Markers
RAST® Individual allergen tests
Total IgE
Phadiatop®
RAST® Mixed allergen tests
Eosinophil Cationic Protein
Tryptase

30. Categories of Immunocaps (>400)
Occupational Allergens (>40):
Enzymes, Latex, Recombinant Latex allergens, Isocyanates, Wood, etc.
Grass/Tree/Weed Pollens
Moulds & Yeasts
Mites
Foods
Insects
Parasites
Drugs

31. Increased probability of clinical reactivity with
elevated levels of IgE antibodies
Sampson (2004) J. Allergy Clin. Immunol.

32. CAP-RAST - Predictive values of allergen-specific IgE levels
Sampson (2004) J. Allergy Clin. Immunol.

33. Specific IgE reactivity after 4 years of avoidance

34. Summary CAP-RAST Use and Function:
Most frequently used to detect sensitivity to high molecular weight
Low molecular weight allergens (LMW); isocyanates, formaldehyde, woods
Value:
Highly specific, however cross-reactivity between allergens is observed
Less sensitive than the Skin Prick Test, especially for LMW and unstable allergens
More expensive than the SPT
Convenient and low risk to the patient

35. Precipitation assay of IgG antibodies to bird antigens (Ouchterlony)
>200 mgA/l
35.9 mgA/l
Negative
Control sera
Specific IgG values
Low
High
Medium
5.4 mgA/l
Allergic Alveolitis
Farmers-,
Mushroom workers-,
Pigeon fanciers Lung
Lopata & Schinkel (2004), Current Allergy & Clin Immunology

36. Quantification of IgG antibodies to Bird antigens
(by CAP-RAST)
Specific IgG [mgA/l] 40 80
120
160
200
Max
Min
75th %
25th %
Median
Serum
Droppings
Feathers
Allergen Mix
Control-Mix
N = 14
N = 9
N = 20
N = 11
Lopata et al (2004), Int Arch Allergy Immunol

37. Quantification of IgG antibodies to Bird antigens
(by CAP-RAST)
Specific IgG [mgA/l]
Max
Min
75th %
25th %
Median 40 80
120
160
200
Serum
Droppings
Feathers
Allergen Mix
Control-Mix
N = 12
N = 4
N = 16
N = 11
Lopata et al (2004), Int Arch Allergy Immunol

38. Summary Laboratory diagnosis of Environmental Exposure and
Sensitisation assist in the confirmation of Occupational Allergy
Assist in the Management of sensitised Worker
and changed working conditions
Sensitisation to unknown/novel agents only possible in close
collaboration between laboratory analyst and
occupational health practitioners
Importantly the results of diagnostic tests should not be viewed
in isolation but rather in context of clinical history/ examination