A method of treating a disease associated with increased levels of chemokine CXCL17. The method includes administering to a subject in need of such treatment a therapeutically effective amount of a substance that lowers the level of CXCL17 activity. The substance can be a CXCL17 antibody, or an antisense compound targeting CXCL17 such as an antisense oligonucleotide or an siRNA. Also provided are methods of treating tumors with CXCL17 and methods of diagnosing a disease associated with increased levels of CXCL17.