CCL2 and atopic asthma: This is demonstrated by the observations that HDM allergen exposure recruits antigen-presenting cells to lung [dendritic cells (DCs)] and skin (Langerhans cells) through the agency of chemokine release (CCL2, CCL5, CCL20, and CXCL10) by epithelial cells (Pichavant et al., 2005), and that humanized SCID mice reconstituted with monocyte-derived DCs from patients with atopic asthma are predisposed to develop immune responses with a Th2 polarization (Hammad et al., 2002).