An interesting novel link between PGD2 and eosinophils is the recent discovery of pro-eosinophilic, so-called pathogenic effector (pe)Th2 lymphocytes, which highly express IL-5 and IL-13, and can be found at elevated levels in eosinophilic patients suffering from atopic dermatitis and eosinophilic gastrointestinal disease. The gene discussed is HPGDS; the disease is atopic eczema.