Table 3.

Some constitutional and environmental factors which may affect susceptibility to antigen and the development of EAA. This listsummarizes factors mentioned in the text

Constitutional	Environmental
Cigarette smoking	Variable antigen exposure
Age (childhood)	Antigen concentration
HLA haplotype	Dusts (particle size)
Cytokines	Immunomodulation
Acute symptoms	Virus infection
Polymorphism	Bacterial LPS and fungal glucan [77]
Tachyphylaxis
Subclinical disease progressionand tissue remodelling/fibrosis