Table 1. Research needs and opportunities: differentiation between chemical contact and respiratory allergens.

Event/characteristics	Potential points of divergence	Research needs and opportunities
Structural characteristics/chemistry	• Valency	Systematic comparison of contact allergens and chemical respiratory allergens
	• Differing electrophilic reaction mechanisms
KEY EVENT 1 Protein reactivity	• Differential amino acid selectivity	A more detailed analysis of the Lys selectivity of respiratory allergens
KEY EVENT 2 Inflammation/elicitation of danger signals	• Differential danger signal/DAMPS	Systematic survey of DAMP expression by contact and respiratory allergens.
	• Differential induction of cytokines and chemokines	Do IL-10 or IL-12 provide selective biomarkers
KEY EVENT 3 DC activation	• Engagement with different DC populations.	Characterisation of phenotypic property of DC associated with immune responses of contact and respiratory allergy
	• Differential activation and/or mobilisation of DC
	• Differential processing
KEY EVENT 4 T lymphocyte activation/proliferation	• Induction of qualitatively divergent immune responses	Identification of allergen-specific T lymphocyte sub-populations in human chemical allergy