CCR6 and allergic disease: Illustrating the difficulty in validating CCL20/CCR6 as a discrete, primary target pairing, CCL2, CCL5, and CXCL10 chiefly act via ligation of CCR1, CCR2, CCR5, and CXCR3 found on DCs of monocyte derivation, and of these combinations, the interaction of CCL2-CCL2R is particularly interesting in allergy development because CCR2+Ly6chi monocytes are precursors of inflammatory CD11b+ DCs found in allergy (Robays et al., 2007; Hammad et al., 2009).