(二) Etiology 5. Atopy 6. Immunological and defensive disturbance 7.Imbalance between sympathetic and parasympathetic nerves systems 8. Deficiency of Vit c and a（二）Etiology • 5.Atopy • 6.Immunological and defensive disturbance • 7.Imbalance between sympathetic and parasympathetic nerves systems • 8.Deficiency of Vit C and A