IL9 and parasitic intestinal disorder: Studies in human have also shown that IL-9 expression increased markedly in response to allergen challenge (Erpenbeck et al., 2003) and IL-9 is highly expressed and localized to tissue lymphocytes during intestinal parasite infection (Faulkner et al., 1998) and to CD3+ cells in bronchial submucosa and BAL (Shimbara et al., 2000).