CCL17 and Alzheimer disease: Keratinocytes can amplify the attraction and production of cytokines by various subsets of T cells through their release of chemokines, including CCL17, CCL22, CCL20, CCL27, CXCL9, CXCL10 and CXCL11 (73, 75, 105, 106), whose expression is increased in AD skin (15, 19, 107–112).