Chemokine (C-C motif) ligand L8 (CCL18), also known as Pulmonary and activation-regulated chemokine (PARC), is produced mainly by antigen-presenting cells of the innate immune system including dendritic cells, monocytes, and macrophages. CCL18 is involved in attracting naïve T-cells, T-regulatory cells, T-helper 2 cells, both immunosuppressive and immature Dendritic Cells, basophils and B-cells (naïve and effector). Aberrant CCL18 expression is observed in many diseases including breast cancer, autoimmunity and hypersensitivity, and it is thought that these abnormal expression patterns play a key role in these diseases.