Poster Presentation The Australasian Society for Immunology 2017 Annual Scientific Meeting

Regional variation in specificity and avidity of serum-specific IgE recognition of major group 1 allergens from temperate and subtropical grass pollen in Australia (#269)

Thina H. Kailaivasan 1 , Janet M. Davies 1 , Victoria L. Timbrell 1 , Lindsay Reibelt 2 , Claire Simmonds 2 , Graham Solley 3 , William Smith 4 , Andrew McLean-Tooke 5 , Sheryl van Nunen 6 , Peter Smith 7 , John W. Upham 8 , Daman Langguth 2
  1. Centre for Children's Health Research, Queensland University of Technology, South Brisbane, QLD, Australia
  2. Sullivan Nicolaides Pathology, Brisbane, Queensland, Australia
  3. Watkins Medical Centre, Brisbane, QLD, Australia
  4. Royal Adelaide Hospital, Adelaide, South Australia, Australia
  5. Sir Charles Gardner Hospital, Perth, WA, Australia
  6. Royal North Shore Hospital and University of Sydney, Sydney, NSW, Australia
  7. Queensland Allergy Services, , Gold Coast, QLD, Australia
  8. The University of Queensland and The Princess Alexandra Hospital, Brisbane, QLD, Australia

Background: Grass pollen (GP) is the major outdoor aeroallergen source important for triggering hayfever and asthma, including thunderstorm-related asthma. Patients in Queensland (subtropical climate) show higher levels of allergic sensitivity to pollens of subtropical grasses Bahia, Johnson (Panicoideae) and Bermuda (Chloridoideae) compared to temperate Ryegrass (Pooideae), whereas patients from temperate regions show higher sensitivity with Ryegrass pollen. We aim to evaluate variation in specific IgE recognition of three major group 1 pollen allergens representing each subfamily of grasses in four Australian regions.

Methods: Sera of 10 GP-allergic patients recruited with informed consent from each of Queensland, Adelaide, Perth and Sydney, selected based on specific IgE concentrations to GP (GP immunotherapy excluded).  Cross-inhibition immunoassays of specific IgE reactivity to purified allergens; Pas n 1 (Bahia GP), Cyn d 1 (Bermuda GP) and Lol p 1 (Ryegrass pollen), were performed.  IC50 and maximum inhibition were determined for Bahia, Johnson, Bermuda, Timothy (temperate) and Ryegrasses GP inhibitors with roasted peanut extract control.

Results: Queensland patient IgE reactivity to Pas n 1 was inhibited strongly by Panicoideae GP, with limited inhibition by other GP, and IgE reactivity with Cyn d 1 was strongly inhibited by Bermuda only.  Conversely, for patients from Sydney, Adelaide and Perth, IgE reactivity to Lol p 1 was inhibited more strongly by Timothy and Ryegrass than any other GP. Whilst patients showed IgE reactivity with Cyn d 1 in Sydney, Perth and Adelaide, it was inhibited to a similar extent by all GP tested.

Conclusions: Capacity for cross inhibition between Panicoideae, Chloridoideae and Pooideae GP differed from each other in each region. Patients showed more specific and avid IgE reactivity to the most biogeographically abundant grasses within their respective regions. Regional variation in allergic sensitivity with diverse GP allergens is clinically important for optimal diagnosis and allergen specific immunotherapy.