Chemokine ligand 20 (CCL20) expressed in the epidermis are a potent impetus for the recruitment of subsets of dendritic cells (DC), B-cells and memory T cells expressing chemokine receptor 6 (CCR6), its exclusive receptor. CCL20 and a corresponding CCR6-expressing immune cell infiltrate have been detected in several malignancies, including melanoma. Yet, the functional contribution of the CCR6/CCL20 axis for the immune control of melanoma remains controversial. The characterization of CCR6-guided immune cell subsets and their functional contribution for the immune control of melanoma comprises the focus of this project. 
We evaluated the homeostatic and inducible secretion of CCL20 by different murine and human melanoma cutaneous cell lines by enzyme-linked Immuno-absorbent assay (ELISA). Both, murine (B16, Ret) and human (A375, C32) melanoma cell lines are capable of secreting CCL20 upon stimulation with pro-inflammatory cytokines (i.e. TNF-α, IL-1α, IL-1β and TGF-β) in vitro. 
In order to determine the functional relevance of CCR6 on local tumor growth, B16 melanoma cells retrovirally transduced with a vector that constantly overexpresses CCL20 (B16-CCL20) were injected subcutaneously in wild type C57BL/6 (WT) and congenic CCR6–knockout (CCR6KO) mice. While animals in both groups developed local tumors, we observed a significantly reduced tumor growth in CCR6KO mice. By contrast, WT and CCR6KO control groups (injected with a B16 line that does not express CCL20) did not display differences in tumor growth rate.  In vitro data excludes the possibility of an autocrine apoptotic pathway. While the precise mechanisms require further investigation, our results suggest that CCL20 interactions in the microenvironment of cutaneous melanoma may be an essential factor for local tumor growth.
Current experimental approaches focus on the identification of the local immune infiltrate by means of Fluorescence activated cells shorting (FACS) and expression of CCR6 and CCL20 in cutaneous melanoma of both WT and CCR6KO mice by means of real-time PCR.

Role of CC-chemokine Receptor 6 (CCR6) and CC Ligand 20 (CCL20) mediated immunosurveillance in malignant melanoma