PTGDR2 and allergic respiratory disease: αX integrin, CRTH2, FcεRII (CD23), and ICAM-1 are up-regulated on eosinophils in eosinophilic eosophagitis (EoE) but not in airway allergies like atopic asthma or allergic rhinitis [5]; IL-25R is up-regulated in mild allergic asthma but not in atopic non-asthmatic subjects [1]; CD44 and CCR3 are down-regulated in EoE but not in airway allergies [5].